i DEPARTMENT OF MARINE AND FISHERIES SCIENCES UNIVERSITY OF GHANA Evaluation of Farm-Made and Commercial Fish Diets for Hapa Culture of Nile Tilapia (Oreochromis niloticus L.) in Ghana Francis Assogba Anani (10120933) This thesis is submitted to the University of Ghana, Legon in partial fulfilment of the requirement for the award of PhD Fisheries Science degree. March, 2015 University of Ghana http://ugspace.ug.edu.gh http://www.ug.edu.gh/news/university-ghana-makes-it-times-higher-education-world-university-rankings ii DECLARATION This thesis is my own work produced from research undertaken under supervision of: ………………………………………… FRANCIS ASSOGBA ANANI (CANDIDATE) ………………………………………… PROF. FRANCIS. K.E. NUNOO (PRINCIPAL SUPERVISOR) ………………………………………… PROF. MATILDA STEINER-ASIEDU (CO-SUPERVISOR) ………………………………………… DR THOMAS N.N. NORTEY (CO-SUPERVISOR) ………………………………………… DR NELSON W. AGBO (CO-SUPERVISOR) University of Ghana http://ugspace.ug.edu.gh iii ABSTRACT One of the major constraints to aquaculture development and expansion in Ghana is affordable nutritionally balanced and cost effective fish diet. Although some fish farmers produce their own farm-made fish diets, these diets do not meet the nutritional requirements of the cultured fish as the farmers do not follow the appropriate feed formulation protocol. This study was carried out to generate information on the commercial fish diets and feed ingredients currently used by small-scale pond fish farmers in five major pond fish farming Regions (Ashanti, Brong-Ahafo, Central, Volta and Western) in Ghana. Six of the commonly used ingredients by the farmers were selected and used to formulate and prepare farm-made tilapia diets which were evaluated against two commonly utilised commercial tilapia diets for Nile tilapia (Oreochromis niloticus). In all, five diets namely A (farm-made diet supplemented with vitamin-mineral premixes, lysine and methionine), B (farm-made diet without supplements), C (commercial tilapia diet, Coppens), D (commercial tilapia diet, Raanan) and E (mixture of B and Raanan in a ratio of 1:1). The first part of the study was conducted in net hapas installed in a 0.2 hectare earthen pond over a 140-day growth period at the Aquaculture Research and Development Centre (ARDEC), Akosombo. O. niloticus with an initial mean weight of 22.8 ± 2.1 g were stocked at a density of 2 fish m -2 and fed at 4-3 % body weight three times a day. The second part of the study involved digestibility of the diets and this was carried out in plastic tanks with 20 L of water each for 20 days. After the culture period, the final mean weights of O. niloticus were 140.3 ± 23.4, 131.0 ± 24.4, 148.3 ± 25.4, 187.6 ± 42.1 and 140.7 ± 28.5 g for A, B, C, D and E respectively. There was no significant difference (p > 0.05) in specific growth rates among all the dietary University of Ghana http://ugspace.ug.edu.gh iv treatments. Apparent nutrient digestibility coefficients were high (> 60 %) in all the dietary treatments. Crude protein ranged from 77.49 to 87.02 %, crude lipid ranged from 81.46-93.90 % whilst carbohydrate (nitrogen free extract) ranged from 65.28 to 85.94 %. Higher crude protein depositions and lower fat contents were observed in the carcass of fish fed farm-made diet A and Raanan. There were no internal and external abnormalities in O. niloticus fed with the various diets. Both the farm-made and commercial diets did not impact negatively on water quality. In terms of cost-effectiveness, the farm-made diets were more profitable than the commercial ones. The results indicated that nutritionally balanced farm-made fish diet is cost-effective and will boost growth of aquaculture in rural areas where semi-intensive pond aquaculture is mainly practised in Ghana. The current fish production (2 500 kg ha -1 yr -1 ) by Ghanaian small-scale pond fish farmers could increase up to a fourfold by using appropriately formulated and prepared farm-made fish diets with locally available ingredients. This is likely to increase their profit margin to over four hundred percent of what they are making currently using commercial fish diets. The costs associated with the use of commercial fish diets by small-scale pond fish farmers are high, and in terms of fish growth and economic returns, the use of appropriately formulated and prepared farm-made diets will be a better alternative. Fish farmers should be trained on the formulation and preparation of nutritionally balanced and cost effective farm-made fish diets so as to reduce their production cost and increase their profit margin. University of Ghana http://ugspace.ug.edu.gh v DEDICATION To my wife, Abigail for her perpetual companionship and support. To my children, Eyram and Likem whose upbringing brings me a sense of responsibility at all times. University of Ghana http://ugspace.ug.edu.gh vi ACKNOWLEDGEMENTS First and foremost, I am thankful to God, the life giver, whose invisible arms sustained and granted me life and valuable insight during this study. My profound thanks go to the supervisors; Prof. Francis K.E. Nunoo of the Department of Marine and Fisheries Sciences (MAFS), Prof. Matilda Steiner-Asiedu of the Department of Nutrition and Food Science and Dr. Thomas N.N. Nortey of the Department of Animal Science all of University of Ghana, Legon, as well as Dr. Nelson W. Agbo of the Department of Fisheries and Watershed Management (DFWM), Kwame Nkrumah University of Science and Technology (KNUST), Kumasi for their guidance during the study. I am gratefully appreciative to MAFS for given me the opportunity to be enrolled as a student for the study. I am indebted to my employer, CSIR-Water Research Institute for partially sponsoring this study. Great appreciation to all my colleagues at the Aquaculture Research and Development Centre, Akosombo for their diverse support. To Messrs Kofi Anyan and Emmanuel Klubi of MAFS for assisting in the water quality analyses as well as Miss Agyari Ohenewaa and Mr. Wisdom Agbeti both of DFWM, for their assistance in the Chromic oxide analysis. I wish to express my heart-felt sincere appreciation to all the Fisheries Extension Officers in all the Regions where the surveys were carried out for their assistance in reaching the farmers and data collection. Finally, many thanks to all the fish farmers and other related groups and individuals who gave me their priceless attention and perishable time to volunteer the necessary information that built the rock- hard foundation for this study. University of Ghana http://ugspace.ug.edu.gh vii TABLE OF CONTENTS DECLARATION………………………………………………………………………………....ii ABSTRACT……………………………………………………………………………………...iii DEDICATION…………………………………………………………………………………...v ACKNOWLEDGEMENTS…………………………………………………………………….vi TABLE OF CONTENTS………………………………………………………………………vii LIST OF FIGURES…………………………………………………………………………….xiii LIST OF TABLES……………………………………………………………………………...xiv LIST OF PLATES……………………………………………………………………………...xvi APPENDICES…………………………………………………………………………………xvii CHAPTER 1.0 INTRODUCTION………………………………………………………………1 1.1 Background Information……………………………………………………………………..1 1.2 Aim of the Study………...…………………………………………………………………….7 1.3 Objectives of the Study……………………………………………………………………….8 1.4 Justification of the Study……………………………………………………………………..9 CHAPTER 2.0 LITERATURE REVIEW……………………………………………………..12 2.1 Fish Consumption Patterns in the World………………………………………………….12 2.2 Contribution of Fish to Human Health and Food Security………………………………14 2.3 Global Production of Aquaculture………….…………………………………...…………16 2.4 Aquaculture Growth and Fish Feeding……………………………………………...…….22 2.5 Production and Use of Fish Feed…………………………………...………………………23 2.6 Feed Ingredient Production and Availability……...………………………………………24 2.6.1 Animal Nutrient Sources……………………………………...…………………………..24 2.6.2 Plant Nutrient Sources…………………………………………………………………....25 University of Ghana http://ugspace.ug.edu.gh viii 2.6.3 Microbial Ingredient Sources………...…………………………………………………..26 2.7 Anti-nutrients in Feed Ingredients………………………………………………………....28 2.8 Culturing of Tilapia…………………………………………………………………………30 2.9 Reproduction in Nile Tilapia……………………………………………..…………………30 2.10 Natural Food and Feeding Habits of Nile Tilapia………………………………………..31 2.11 Growth of Nile Tilapia……………………………………………………………………..32 2.12 Use of Formulated Feeds for Nile Tilapia………………………………………………...33 2.13 Feeding Schedules (Rates and Frequencies) for Cultured Tilapia……………………...34 2.14 Nutritional Requirements of Nile Tilapia…………………………………………….......35 2.15 Nutritional Deficiencies in Nile Tilapia…………………………………………………...40 2.16 Pond Culture…………………………………………..…………………………………...43 2.17 Use of Hapa in Fish Rearing…………………..…………………………………………..45 2.18 Hapa-Cum-Pond Culture System………………………………………...……………….46 2.19 Water Quality in Aquaculture…………………………………………..………………...47 2.19.1 Water Quality Parameters for Tilapia……………………………………………..…...48 CHAPTER 3.0 METHODOLOGY…………………………………………………………….50 3.1 Selection of Study Area for Survey of Fish Feed Ingredients and Commercial Fish Diets……………………………………………………………………………………..50 3.2 Pre-Survey of Fish Feed Ingredients and Commercial Fish Diets Activities……………51 3.3 Data Collection………………………………………………………………………………52 3.4 Selection of Feed Ingredients and Commercial Fish Diets………………………………..54 3.5 Procurement of Selected Feed Ingredients and Commercial Fish Diets…………………54 3.6 Storage of Ingredients and Commercial Fish Diets……………………………………….55 3.7 Determination of the Proximate Compositions of Ingredients and Diets………………..55 University of Ghana http://ugspace.ug.edu.gh ix 3.7.1 Moisture and Dry Matter Determination………………………………………………..55 3.7.2 Ash Determination………………………………………………………………………...56 3.7.3 Crude Protein Determination…………………………………………………………….56 3.7.4 Crude Lipid Determination………………………………………………………………57 3.7.5 Crude Fibre Determination………………………………………………………………58 3.7.6 Nitrogen Free Extracts (NFEs) Determination………………………………………….58 3.7.7 Phosphorus Determination……………………………………………………………….58 3.7.8 Gross Energy (GE) Determination……………………………………………………….60 3.7.9 Chromic Oxide Analysis…………………………………………………………………..60 3.8 Study Area for Diet Formulation, Preparation and Evaluation………………………….60 3.9 Diet Formulation and Preparation…………………………………………………………61 3.10 Experimental System………………………………………………………………………66 3.11 Experimental Fish……………………………………………………………………….....68 3.12 Conditioning and Stocking of Experimental Fish……………………………...………...69 3.13 Feeding Schedule……………………………………………………………………...……69 3.14 Measurements of Fish during Growth Study…………………………………………….71 3.15 Monitoring of Water Quality Parameters………………………………………………..72 3.15.1 Determination of Water Quality Parameters in the Field……………………………..72 3.15.2 Determination of Water Quality Parameters in the Laboratory……………………..73 Alkalinity………………………………………………………………………………………………………………………74 Ammonia………………………………………………………………………………….74 Hardness……………………………………………………………………………………………………………………….75 Nitrates………………………………………………………………………………………………………………………….76 Nitrites………………………………………………………………………………………………………………………….77 Phosphate………………………………………………………………………………………………………………………78 Total Suspended Solids (TSS)……………………………………………………………………………………….79 3.16 Determination of Biological Parameters………………………………………………….79 University of Ghana http://ugspace.ug.edu.gh x 3.16.1 Growth Performance…………………………………………………………………….79 3.16.1.1 Mean Weight Gain (MWG)…………………………………………………………...79 3.16.1.2 Specific Growth Rate (SGR)…………………………………………………………..80 3.16.2 Survival Rate (SR)……………………………………………………………………….80 3.16.3 Feed Conversion Ratio (FCR)…………………………………………………………...80 3.16.4 Feed Efficiency (FE)……………………………………………………………………..81 3.16.5 Length-Weight Relationship…………………………………………………………….81 3.16.6 Condition Factor (K)…………………………………………………………………….82 3.16.7 Energy Retention (ER)…………………………………………………………………..83 3.16.8 Hepatosomatic Index (HSI)……………………………………………………………...83 3.16.9 Protein Efficiency Ratio (PER)………………………………………………………….83 3.16.10 Protein Productive Value (PPV)……………………………………………………….83 3.16.11 Apparent Digestibility Coefficients (ADC)……………………………………………84 3.17 State of Fish Health………………………………………………………………………...85 3.18 Economic Analyses of Diets………………………………………………………………..86 3.18.1 Incidence Cost (IC)………………………………………………………………………87 3.18.2 Profit Index (PI)………………………………………………………………………….87 3.19 Data Analyses………………………………………………………………………………87 CHAPTER 4.0 RESULTS………………………………………………………………………89 4.1 Fish Feed Ingredients Used by Fish Farmers in Ashanti, Brong-Ahafo, Central, Volta and Western Region…………………………………………………………………89 4.2 Commercial Fish Diets Used by Fish Farmers in Ashanti, Brong-Ahafo, Central, Volta and Western Region…………………………………………………………………92 4.3 Use of Fish Diets by Fish Farmers in Ashanti, Brong-Ahafo, Central, Volta and Western Region…………………………………………………………………94 4.4 Use of Commercial Fish Diets by Fish Farmers in Ashanti, Brong-Ahafo, Central, Volta and Western………………………………………………………………………….96 University of Ghana http://ugspace.ug.edu.gh xi 4.5 Proximate Compositions of Selected Ingredients………………………………………….97 4.6 Proximate Compositions of Study Diets…………………………………………………...98 4.7 Experimental Fish………………………………………………………………………….100 4.8 Growth Performance of Cultured Fish…………………………………………………...100 4.9 Feed and Nutrient Efficiency of Cultured Fish…………………………………………..105 4.10 Length-Weight Relationship by Diet Type……………………………………………...107 4.11 Health Status of O. niloticus according to Diet Type...…………………………………110 4.12 Body Composition of Cultured O. niloticus……………………………………………..111 4.13 Cost Effectiveness of the Diets…………………………………………………………...114 4.14 Water Quality……………………………………………………………………………..116 4.15 Apparent Digestibility Coefficients of Nutrients in the Diets………………………….120 CHAPTER 5.0 DISCUSSION…………………………………………………………………122 5.1 Use of Fish Feed Ingredients………………………………………………………………122 5.2 Use of Commercial Fish Diets……………………………………………………………..124 5.3 Use of Fish Diets in the Five Regions……………………………………………………..125 5.4 Proximate Compositions of Ingredients Used in Diet Formulation and Preparation…128 5.5 Proximate Compositions of Farm-Made and Commercial Diets……………………….129 5.6 Growth Performance of the Cultured O. niloticus……………………………………….132 5.7 Feed and Nutrient Efficiency of the Cultured O. niloticus………………………………135 5.8 Length-Weight Relationship of the Cultured O. niloticus……………………………….139 5.9 Condition Factor of the Cultured O. niloticus……………………………………………140 5.10 State of Health of the Cultured O. niloticus……………………………………………..140 5.11 Whole Body Composition of the Cultured O. niloticus………………………………...143 5.12 Effect of the Diets on Water Quality…………………………………………………….145 University of Ghana http://ugspace.ug.edu.gh xii 5.13 Apparent Nutrient Digestibility of Diets………………………………………………...145 5.14 Cost Effectiveness of Diets………………………………………………………………..150 CHAPTER 6.0 CONCLUSION AND RECOMMENDATIONS…………………………...152 6.1 Conclusion………………………………………………………………………………….152 6.2 Recommendations for Research and Policy……………………………………………...157 6.2.1 Research…………………………………………………………………………………..157 6.2.2 Policy……………………………………………………………………………………...159 REFERENCES…………………………………………………………………………………161 APPENDICES………………………………………………………………………………….206 University of Ghana http://ugspace.ug.edu.gh xiii LIST OF FIGURES Figure 3. 1 Map showing the five Regions in Ghana (where the survey of fish feed ingredients and commercial fish diets were conducted are indicated by the red spots………………………………………………………………………...51 Figure 3. 2 WRI, ARDEC, Akosombo where the feed trials were conducted……………….61 Figure 4. 1 Percentage of fish diet types used by fish farmers in Ashanti, Brong-Ahafo, Central, Volta and Western Region……………………………………………….95 Figure 4. 2 Percentage of fish farmers that used the various types of fish diets in Ashanti, Brong-Ahafo, Central, Volta and Western Region…………………….95 Figure 4. 3 Percentage of fish farmers using the various types of commercial fish diets in Ashanti, Brong-Ahafo, Central, Volta and Western Region………………….96 Figure 4. 4 Growth performance of Oreochromis niloticus fed commercial and farm-made fish diets for twenty weeks……………..……………………………102 Figure 4.5 Weight gain by Oreochromis niloticus fed commercial and farm-made fish diets for 20 weeks……………………………………………………………..102 Figure 4. 6 Percentage final wet weight distributions of Oreochromis niloticus fed farm-made and commercial fish diets for 20 weeks………………………..103 Figure 4. 7 Length-weight relationship of Oreochromis niloticus fed farm-made diet A….107 Figure 4. 8 Length-weight relationship of Oreochromis niloticus fed farm-made diet B…108 Figure 4. 9 Length-weight relationship of Oreochromis niloticus fed Coppens…………….108 Figure 4. 10 Length-weight relationship of Oreochromis niloticus fed Raanan…………....109 Figure 4. 11 Length-weight relationship of Oreochromis niloticus fed diet E……………...109 University of Ghana http://ugspace.ug.edu.gh xiv LIST OF TABLES Table 2. 1 Anti-nutrient compounds and their biological effects on animals………………..29 Table 2. 2 Feeding schedules for various sizes of tilapia in semi-intensive and intensive culture in freshwater ponds………………………………………………………...35 Table 2. 3 Dietary protein needs for Nile tilapia, Oreochromis niloticus by life stage…......36 Table 2. 4 Essential amino acid needs of Nile tilapia, Oreochromis niloticus as % of dietary protein and of total diet…………………………………………....36 Table 2. 5 Crude lipid, essential fatty acids and energy needs for growth of Oreochromis niloticus (% dry feed)………………………………………………...37 Table 2. 6 Mineral requirements of Oreochromis niloticus (% of dry feed except otherwise mentioned)………………………………………38 Table 2. 7 Vitamin needs of Oreochromis niloticus (% of dry feed except otherwise mentioned)………………………………………………………………..39 Table 2. 8 Dietary nutritional deficiency of essential amino acid and essential fatty acid….40 Table 2. 9 Dietary mineral deficiency signs and symptoms associated with tilapia species………………………………………………………………………………...41 Table 2. 10 Specific vitamin deficiencies associated with tilapia species…………………….42 Table 2. 11 Water quality tolerance by some commonly cultured fish species……………...48 Table 2. 12 Water quality parameters for tilapia……………………………………………..49 Table 3. 1 Number of pond fish farmers in Ghana on regional basis in 2011……………….50 Table 3. 2 Inclusion levels (%) of ingredients used in diets A and B and their cost per kilogramme…………………………………………………………………………..62 Table 3. 3 Composition of the vitamin-mineral premix used in diet A………………………63 Table 3. 4 Constituent of Coppens (Diet C) as indicated on the label of the feed bag………65 Table 3. 5 Constituent of Raanan (Diet D) as indicated on the label of the feed bag……….66 Table 3. 6 Criteria used at the end of the growth study for fish health observations………86 Table 4. 1a Checklist of utilized fish feed ingredients in Ashanti, Brong Ahafo, Central, Volta and Western Region of Ghana……………………………………………..90 Table 4. 1b Checklist of utilized fish feed ingredients in Ashanti, Brong Ahafo, Central, Volta and Western Region of Ghana……………………………………………..91 University of Ghana http://ugspace.ug.edu.gh xv Table 4. 2 Checklist of commonly utilized commercial fish feeds in Ashanti, Brong Ahafo, Central, Volta and Western Regions of Ghana…………………..93 Table 4. 3 Proximate compositions (% as-fed), gross energy (kJ g -1 ), phosphorous (%) and prices (GHS kg -1 ) of the selected feed ingredients used in the formulation and preparation of diets A and B….....................................................97 Table 4. 4 Proximate composition (% as-fed), gross energy (kJ g -1 ), phosphorous (g kg -1 ), Chromic oxide concentrations and prices (GHS kg -1 ) of Diets A, B, Coppens, Raanan and E……………………………………………...98 Table 4. 5 Percentage deviation of the observed from the expected crude proteins of the various diets…….................................................................................................100 Table 4. 6 Mean growth performance of the cultured Nile tilapia fed diets A, B, Coppens, Raanan and E for 20 weeks…………………………………………….104 Table 4. 7 Feed and nutrient efficiency of the cultured Nile tilapia fed diets A, B, Coppens, Raanan and E for 20 weeks……………………………………………..106 Table 4. 8 Equation parameters of Length-weight and condition factors for Oreochromis niloticus fed diets A, B, Coppens, Raanan and E………………….110 Table 4. 9 Whole body proximate composition (%) gross energy (kJ g -1 ) and hepatosomatic index of cultured Nile tilapia (mean ± SD)………………………113 Table 4. 10 Cost effectiveness of diets fed to Nile tilapia……………………………………115 Table 4. 11 Summary of statistical analysis of water quality parameters for the various dietary treatments and the open pond water for a period of 140 days………..116 Table 4. 12 Proximate compositions (%) of faecal samples of Oreochromis niloticus fed the various diets……........................................................................................120 Table 4. 13 Apparent digestibility coefficients (%) of dry matter, crude protein, crude lipid, nitrogen free extract, crude fibre, ash, gross energy and phosphorus in the various diets fed to Oreochromis niloticus….........................121 University of Ghana http://ugspace.ug.edu.gh xvi LIST OF PLATES Plate 3.1 Interaction with fish farmers in the Prestea Huni-Valley District of Western Region, Ghana…………………………………………………………........53 Plate 3.2 Using hand-operated meat mincer to pellet prepared fish diet…………………....64 Plate 3.3 Experimental hapas being mounted in a 0.2 hectare earthen pond at ARDEC, Akosombo…...................................................................................................67 Plate 3.4 Measuring of physico-chemical parameters in an experimental hapa in the pond………………………………………………………………………………..73 University of Ghana http://ugspace.ug.edu.gh xvii APPENDICES I Informed Consent Form……………………………………………………………………206 II Fish Feeds and Feed Ingredients Survey…………………………………………………..208 III Mean Living Weight (± SD) for each Treatment during Growth Trials………………..215 IV Detailed Water Quality Parameter Range for the Various Dietary Treatments and Open Pond Waters during Growth Trials……………………………...216 University of Ghana http://ugspace.ug.edu.gh 1 CHAPTER 1.0 INTRODUCTION 1.1 Background Information The growing demand for fish protein in Ghana has motivated active development of aquaculture both at the commercial and peasant levels. The contribution of aquaculture production to the Ghanaian economy has grown over the past decade, with an annual average growth rate of 12.4% (FAO, 2006–2012). Aquaculture is seen as an important foreign exchange earner, contributes to food security as well as providing much needed employment to many people in Ghana. The Ghana National Aquaculture Development Plan (GNADP) designed in 2012 and launched in 2014 was to increase the national fish stock from 27, 750 metric tonnes to 130, 000 metric tonnes in six years (GNADP, 2012). The GNADP is intended to generate about 220, 000 jobs within the same period. In general, fisheries are estimated to contribute 3 % of the total national gross domestic product (GDP) and 5 % of the agriculture GDP of Ghana (FAO, 2006–2012). Aquaculture is defined by FAO (1990) as “the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants with some sort of intervention in the rearing process to enhance production, such as regular stocking, feeding and protection from predators”. Farming of aquatic organisms may be individual or corporate ownership of the stock being cultivated. Increasing production capacity of aquaculture resources through intensification seems to be the way forward to meet the ever increasing demand for fish. This entails increasing primary, intermediate and terminal productivity capacities of our natural aquatic ecosystem and creation of productive artificial aquatic University of Ghana http://ugspace.ug.edu.gh 2 ecosystems through proper planning, development and management (Sadiku and Jauncey, 1995). The first scientifically managed aquaculture facility in Ghana was put up by the University of Ghana at its Agricultural Research Station situated near Nungua, Accra in 1959. By 1969, there were about 220 reservoirs of variable sizes in Northern Ghana (FAO, 2006–2012). In the 1980s, aquaculture received a major boost, especially in the Ashanti, Central, Eastern, Western and Greater Accra regions, this time from government as a way of meeting Ghana’s fish deficit (Mensah et al., 2006). Most fish farmers in Ghana use earthen ponds and rely on natural productivity while others supplement with agricultural by-products. Other systems of culture include the cages, pens and raceway systems, which are not commonly practised nationwide (Awity, 2005). In terms of numbers, cages come after ponds. For instance, in 2012, a total of 2, 278 cages whilst 4, 749 ponds were recorded in the country (FD, 2013). However, fish production during the year was higher in cages than in ponds. Production from ponds was 1, 771.50 and that of cages was 24, 248.50 metric tonnes. The Nile tilapia (Oreochromis niloticus) is the major tilapia species cultured in Ghana. Most of the fish produced are either consumed directly by fish farmers or sold locally. Currently, there is a ban on tilapia import in Ghana (FAO, 2006–2012) and so there is a call for an increase in its production locally. However, there are constraints to the expansion of aquaculture in Ghana of which the main one being high cost of fish feed. University of Ghana http://ugspace.ug.edu.gh 3 Feed is known to be a major determinant of successful growth and intensification of aquaculture production. It accounts for a major part (30-70 %) of the total operation cost of an average fish farm (El-Sayed, 2004; Rumsey, 1993). It is generally accepted that the highest recurring cost in aquaculture comes from feeds. Alone, feed accounts for about 60-80 per cent of operational costs in intensive aquaculture (Rola and Hasan, 2007). With the increasing demand for food fish and the decline in capture fisheries production, aquaculture in Ghana is shifting from low density to high density culture that is traditional to semi-intensive or intensive culture. This will consequently lead to an unprecedented rise in the demand for feeds more than that of fertilizers (Kaushik, 1990). Aquaculture in Ghana started with the use of no feed, then the use of farm-made feeds to factory-made feeds. This demonstrates a real possibility of increasing production and reveals the potential importance of fish feeds in Ghana. Now aquaculture feeds have been considered a major subsector of the feed milling industry (Kaushik, 1990). From the economic point of view, feed cost appears to be one of the major constraints against the greater expansion of aquaculture. Fish meal is the major dietary protein source for fish feeds, commonly making up between 20˗60 % of fish diets (FAO, 2012a; Glencross et al., 2007; Watanabe, 2002). It has been estimated that in 2008, the aquaculture sector used 60.8˗71.0 % of world fish meal production (FAO, 2012a; Lim et al., 2008; Tacon and Metian, 2008). Dietary protein is the major and most expensive component of formulated fish feeds (Wilson, 2002) and feed costs have tended to increase with the rising price of fish meal. For instance, the cost of fish feeds increased by 73 % from 2005 to 2008 (FAO, 2012a). University of Ghana http://ugspace.ug.edu.gh 4 Therefore, in order to reduce feed costs and the use of fish meal in aquafeeds, more extensive use of alternative feed ingredients is needed (Burr et al., 2012; Hardy, 2010; Lim et al., 2008; Glencross et al., 2007). Although plant protein such as soybean meal has been used in fish feeds as a replacement for animal protein, trash fish (fish meal of marine origin) is still the main dietary protein source comprising 20˗60% of the feed (Da et al., 2011; Phumee et al., 2009; Hung and Huy, 2007). However, using fish meal is not a sustainable long-term feeding strategy (FAO, 2010; Naylor et al., 2009), because it will lead to the decline or extinction of some trash fish species (Edwards et al., 2004). As the aquaculture industry is projected to continue expanding, fish meal must be used more strategically as the required aqua feed production volumes increase (Güroy et al., 2012). This poses a major challenge for thousands of small-scale fish farmers, as the feed is a major component of the total production costs and many fish feed producers still rely heavily on trash fish and fish meal (Tacon and Metian, 2008). In 1993, Rumsey documented that cost effective practical aquaculture feeds can be produced without the use of fish meal with no apparent loss in fish growth in some species such as tilapia. Despite the fact that most plant ingredients are readily available at a lower cost than fish meal, their use within fish feeds is usually restricted by relatively low protein content, unbalanced essential amino acid profile, high levels of fibre and starch and the presence of one or more anti-nutritional factors (Agbo et al., 2011; NRC, 1993). University of Ghana http://ugspace.ug.edu.gh 5 Increased use of cheap, locally available feed resources and more sustainable protein sources is considered a high priority in fish feed industry that could provide a way to reduce the total production costs (Hardy, 2010; Edwards and Allan, 2004). Other studies have also shown the use of different types of feedstuffs in traditional aquaculture, ranging from kitchen wastes and foliage in homestead-type fish farming to fishery and agro- industrial by-products like oil cakes, wheat and rice bran, mill wastes, brewery waste, bean residues, silkworm pupae, poultry wastes, slaughterhouse wastes (blood and entrails), trash fish and fish offal (Pillay and Kutty, 2005). Cocoa pod husk and groundnut peel have also been used (Ofori, 2001). The most important characteristics of feedstuffs are the bioavailability of nutrients; hence, reliable data on different ingredients for each species need to be well considered as a necessary prerequisite (Fagbenro et al., 2003; Jauncey, 1993). Digestibility of nutrients in fish diets needs to be studied because it is the digested feed which is absorbed and made available for cellular metabolism. The resultant of which are tissue synthesis and repair of worn-out tissues and various energy utilization channels (NRC, 1993; Yudkin, 1985). Borghesi et al. (2007) reported that knowing nutrient digestibility of feed ingredients elicit interchangeability of feed ingredients without reducing animal performance. De Silva and Anderson (1995) also observed that it is essential to have knowledge of the digestibility of the main ingredients as well as of the whole diet in feed formulation and manufacture. In combination, chemical analysis and apparent digestibility coefficient (ADC) results allow us to precisely estimate not only the contribution of a particular protein source to a complete fish feed but also how much feed University of Ghana http://ugspace.ug.edu.gh 6 wastes and undigested nutrients (faeces) will potentially accumulate in fish pond (Jimoh et al., 2010; Koprucu and Ozdemer, 2005). Local or sub-regional agricultural by-products could provide nutritionally sound and cost- effective feeds to support increased fish production in Ghana (Agbo, 2008). In order to increase and sustain aquaculture production in Ghana, there is the need to encourage use of the abundant locally available ingredients to develop low cost feeds and discourage import of very expensive formulated or pelletised feed from abroad (Agbo, 2008). Thus, production of fish diets using locally available feed ingredients for small-scale fish farming in Ghana is the way forward to increase the profitability of the industry and make the production more sustainable. In Ghana, there are a variety of agro-based industrial wastes, such as oil palm waste, pineapple waste, cassava waste, pawpaw waste, yam waste, and coconut waste. Efforts have been made to make use of these organic wastes in formulating feeds for animals, including fish. In addition to selecting the proper feeds or ingredients to develop cost effective feeds that will maximize growth, appropriate feed management and feeding practices are critical to obtaining efficient aquaculture production and minimizing pollution of the aquatic environment (NRC, 2011). It is against this background that this study was designed to find answers to the following research questions: University of Ghana http://ugspace.ug.edu.gh 7  What types of feed ingredients and commercial fish diets are being used by small- scale pond fish farmers in five major pond fish farming regions (Ashanti, Brong Ahafo, Central, Volta and Western) of Ghana?  What are the chemical constituents of the commonly used feed ingredients and commercial fish diets by the fish farmers?  What are the biological utilization levels of the commonly used commercial fish diets and farm-made (formulated) diets from the commonly used feed ingredients when fed to O. niloticus?  What is the state of health of O. niloticus when fed separately with the farm-made diets and the commonly used commercial ones?  Does feeding O. niloticus with the farm-made and commercial diets negatively impact on the physiological well-being (condition factor) of the fish?  Do the farm-made diets and commonly used commercial fish diets negatively impact pond/hapa water quality?  Does the water quality in the pond/hapa negatively impact on the condition factor of the cultuered fish?  Is the farm-made diets relatively cost-effective compared with the commonly used commercial ones? 1.2 Aim of the Study This study was to generate information on the feed ingredients and commercial fish diets currently used by small-scale pond fish farmers in five major pond fish farming regions University of Ghana http://ugspace.ug.edu.gh 8 in Ghana and to evaluate the commonly used commercial fish diets and farm-made diets produced with selected commonly used ingredients for O. niloticus. 1.3 Objectives of the Study The specific objectives were to: 1. Conduct a survey of feed ingredients and commercial fish diets small-scale pond fish farmers are currently using for fish production in five main pond fish farming Regions of Ghana; 2. Determine the proximate compositions of commonly used feed ingredients and commercial fish diets by small-scale pond fish farmers in five main pond fish farming Regions of Ghana; 3. Evaluate two most commonly used commercial diets and two farm-made diets formulated and prepared using six selected commonly used feed ingredients on growth and feed utilization of O. niloticus; 4. Evaluate the digestibility of the commercial fish diets and the compounded ones in O. niloticus; 5. Assess the state of health and physiological well-being (condition factor) of O. niloticus when fed separately with the farm-made diets and that of commercial ones; 6. Assess the effect of the farm-made diets and that of the commercial ones on water quality; 7. Assess the effect of water quality in the hapas on the growth of the fish and 8. Evaluate the cost effectiveness of the farm-made and commercial diets. University of Ghana http://ugspace.ug.edu.gh 9 1.4 Justification of the Study Pond fish farming is on the increase in all the ten (10) Regions of the country (FD, 2013). Most of these farmers are small-scale producers who cannot afford the ever escalating cost of commercial fish diets. This could discourage most of them from being in the fish farm business which will negate national efforts on food security. Furthermore, there is a paucity of information on the nutrient contents of commercial fish feeds in Ghana as well as no reliable published information on chemical composition of these products (Personal Observation). Although there are guidelines for the establishment of a new fish feed industry (GNADP, 2012) these are yet to be enforced. Hence, there is a great possibility that fish farmers may be deceived by the commercial feed manufacturers due to the quality assurance gap. Therefore, there is an urgent need to assess the actual chemical composition and nutritive value of commercial fish feeds and ingredients used by fish farmers in the country. Small-scale fish farmers may use ingredients based on location, affordability and seasonality. Plant feedstuffs are known to contain anti-nutritional factors (ANFs). ANFs limit the use of plant feedstuffs at high dietary inclusion levels in compounded fish feeds (Tacon, 1993). This study will provide appropriate information to small-scale fish farmers on the availability, proximate composition and the optimal inclusion levels of used ingredients in farm-made fish diet productions so that the farmers could develop suitable farm made fish feeds. Hence, small-scale fish farmers will be knowledgeable in the appropriate feed ingredients to utilize in their formulations as well as including each of them at their optimal levels. University of Ghana http://ugspace.ug.edu.gh 10 Currently, most commercial fish diets in Ghana are imported from Brazil and United States of America (USA) and they are prohibitively expensive for small-scale fish farmers to buy. Although some of these farmers could afford the cost of these diets, but with much difficulty. Consequently, most of the farmers have resorted to feeding their cultured fish with food scraps and food wastes from their farming activities. This practice makes the cultured fish take a significantly longer time period (10-12 months) to reach market size (Ashanti, Brong-Ahafo and Central Regional Small-Scale Fish Farmers Associations; Personal Communication). Farmers who compound their own feeds produced unbalanced diets as their productions do not follow an appropriate feed formulation protocol so as to meet the nutritional requirements of the target fish (Personal Observation). Imported commercial fish feeds continue to flood the local market due to the intensification of O. niloticus and expansion of the aquaculture industry in recent years. This is particularly in the Eastern and some parts of Volta Regions where cage fish farming is widespread due to the presence of the Volta River. Some of these commercial feeds may be of poor quality, and may not meet the nutritional requirements of the target fish. Currently, about sixteen (16) of these feeds have been recorded in the Eastern Region alone (Personal observation). Unlike quality commercial poultry feeds, that are readily available in Ghana, there is an acute paucity of nutritionally sound, cost effective feeds for finfish in general, and for O. niloticus in particular. University of Ghana http://ugspace.ug.edu.gh 11 It is therefore necessary that data is gathered on the commercial fish feeds and feedstuffs currently utilized by small-scale pond fish farmers in Ghana so as to evaluate them for O. niloticus as it is the main fish cultured in the country. Ultimately, it is anticipated that value addition to the used feed ingredients in the five Regions will be a major contribution towards production of quality fish feed, cutting back fish feed cost and increasing the returns from fish farming in the country. The use of appropriate, cheap and locally available feed ingredients in farm-made fish feed production is necessary to increase fish farming yield, improve food security, reduce poverty among rural folks and create employment. University of Ghana http://ugspace.ug.edu.gh 12 CHAPTER 2.0 LITERATURE REVIEW 2.1 Fish Consumption Patterns in the World Global food fish supply has grown steadily in the last five decades, at an average annual rate of 3.2 percent, outpacing world population growth (1.6 %). Therefore, average per capita availability has risen. World per capita apparent fish consumption increased from an average of 9.9 kg (live weight equivalent) in the 1960s to 17.0 kg in the 2000s and 18.9 kg in 2010, with preliminary estimates for 2012 pointing towards further growth to 19.2 kg (FAO, 2014). However, there are distinct regional differences; the lowest consumption is in Africa (9.1 kg/capita), followed by 9.9 kg for Latin America and the Caribbean, 20.7 kg for Asia, 22.0 kg for Europe, 24.1 kg for North America, and 24.6 kg for Oceania (FAO, 2012a, 2012b). Although consumption has grown steadily in developing regions (5.2 kg in 1961 to 17.0 kg in 2009) and in low-income food-deficit countries (LIFDC; 4.9 kg in 1961 to 10.1 kg in 2009), levels are still considerably less than in more developed regions. These aggregate figures cover a very wide variation in consumption, influenced by location, tradition, household customs, fish access, trade connections, market power, and emerging consumption drivers such as urbanization, income distribution changes, and retail development (FAO/SFLP, 2008). In Africa, fish provides about 22 % of the protein intake in sub-Saharan Africa (SSA) (FAO, 2012b). This can, however, exceed 50 % in the poorest countries, especially where other sources of animal protein are scarce or expensive (WorldFish Center, 2005). Per capita fish consumption has remained static or decreased in some countries in SSA (e.g. the Congo, South Africa, Gabon, Malawi and Liberia), whilst the most substantial University of Ghana http://ugspace.ug.edu.gh 13 increases in annual per capita fish consumption have occurred in North Africa (from 2.8 kg in 1961 to 10.6 kg in 2009) (FAO, 2012b). Of the 126 million tonnes available for human consumption in 2009, fish consumption was lowest in Africa (9.1 million tonnes with 9.1 kg per capita). This has been attributed to levelling off in capture fish production and increasing population growth (World Bank, 2004). Based on 1997 levels of production, aquaculture would have to increase by 267 % by 2020 to maintain the current fish consumption level in Africa (Delgado et al., 2003). In Ghana, fish is the preferred source of animal protein and it is consumed by the majority of the people. Ghana is among the highest fish consuming countries in the world, with an average per capita consumption of 25 kg. With a population of approximately 24 million fish demand for 2012 was estimated at 968, 000 metric tonnes, whilst fish production for the same year stood at 486, 000 metric tonnes (MoFA, 2013). About 175, 000 metric tonnes of fish were imported at an estimated cost of $ 157 million to make up for the shortfall. The demand for fish is higher than what total domestic fish catch can supply and the gap is widening year after year. Fish provides approximately 60 % of the animal protein consumed in Ghana (GFAR, 2011). About 75 % of the total domestic fish (captured and farmed) is consumed locally. The preferred fish species in Ghana are the sea bream, red snapper and croaker but these are expensive and unaffordable by the majority of the population. Thus, the affordable types-mackerel, horse mackerel, chub mackerel, sardines and tuna are mostly consumed (GFAR, 2011). University of Ghana http://ugspace.ug.edu.gh 14 2.2 Contribution of Fish to Human Health and Food Security Consumption of fish can play a key role in access to proteins, minerals, and essential fatty acids, and can have a significant impact for maternal and early child health (Kawarazuka and Béné, 2011; Thilsted et al., 1997). There is evidence of beneficial effects of fish consumption (FAO/WHO, 2011) in relation to coronary heart disease (Mozaffarian and Rimm, 2006) stroke, age-related muscular degeneration and mental health (Peet and Stokes, 2005). Also, increasing consumption of fish has been found to enhance learning in children, protects vision and eye health, and offers protection from cardiovascular disease and some cancers (FAO, 2012b). The role of small indigenous fish species, which are often given less prominence in fishery or aquaculture development, can be very critical for poorer households in reducing protein, vitamin and mineral (especially calcium and iodine) deficiencies (Roos et al., 2007). Food fish currently represents the major source of animal protein (contributing more than 25 percent of the total animal protein supply) for about 1 250 million people within 39 countries worldwide, including 19 sub-Saharan countries (FAO, 2009). Fish contributes more than 50 percent of protein intake for about 400 million people from the poorest African and South Asian countries. The quality of fish protein compares very well with that of meat and relatively fish digestion is easier than that of meat (Steiner-Asiedu et al., 1993). The ease of digestion makes it an excellent protein source in complementary foods for young child feeding, especially in less developed countries. Fish provides not only high-value protein, but also a wide range of essential micronutrients, including various vitamins (A, B, D and E), and minerals (including calcium, iodine, zinc, iron and University of Ghana http://ugspace.ug.edu.gh 15 selenium) and polyunsaturated omega-3 fatty acids (mainly docosahexaenoic acid and eicosapentaenoic acid) (FAO, 2012b; Roos et al, 2007). Generally, fish is usually low in saturated fats and cholesterol. The fats and fatty acids in fish, particularly the long chain n-3 fatty acids (n-3 polyunsaturated fatty acids (PUFAs)), are highly beneficial and difficult to obtain from other food sources (Kawarazuka and Béné, 2011). Of particular importance are eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n- 3, DHA). With a primary policy focus on access to food calories, fish or aquatic foods have been relatively under-recognized in their contribution to global food supply and food security (FAO, 2012b). However, in 2009, fish accounted for 16.6% of the world’s intake of animal protein and 6.5% of all protein consumed, providing around 4.3 billion people with about 15% of their animal protein. With growing recognition of the need to define global targets of food sufficiency and security by nutritional quality (FAO, 2012b; Shetty, 2009), particularly in maternity and early life stages, the role of fish is becoming much more clearly appreciated. Interactions between fishing and food security are also critical in many parts of the world, where small-scale and often seasonal fishing activity provides both income and household food supply, and there is common concern that over-zealous regulation and removal of fishing capacity may cause more negative social and nutritional impact than the resource efficiency gains being sought (Béné et al., 2010). However, though aquaculture might supplement or compensate for capture fisheries, Beveridge et al. University of Ghana http://ugspace.ug.edu.gh http://animalfrontiers.org/content/3/1/28.full#ref-16 http://animalfrontiers.org/content/3/1/28.full#ref-5 http://animalfrontiers.org/content/3/1/28.full#ref-6 16 (2010) note its constraints of meeting lowest income social objectives, as small- and medium-scale commercial producers and wealthier market/retail consumers are more likely to benefit. However, through market displacement, by producing smaller indigenous species in polycultures, and/or by providing occasional employment for cash or food, additional benefits may be provided for poorer groups. There are also important consequences of trading fish for other food items, either locally or at the market economy level (Kurien, 2004). In favourable conditions this can create advantages for all parties, widening and expanding nutritional options for catchers/producers of fish while improving access to key foodstuffs. This is particularly valuable for peri-urban supplies and urban markets, though there may be issues of reduced local market access where higher urban prices drive out purchasing options. The development of infrastructure–road access, ice production, and market facilities may also accelerate the shift to urban markets. However, there are also specific challenges with meeting needs of poor urban dwellers (Ruel et al., 2008), particularly where urbanization is rapid and is not accompanied by strong employment opportunities. It is clear that expansion of fish supplies will be essential to meet future food needs. 2.3.1 Global Production of Aquaculture Global food fish aquaculture production expanded at an average annual rate of 6.2 percent in the period 2000–2012, more slowly than in the periods 1980–1990 (10.8 percent) and 1990–2000 (9.5 percent) (FAO, 2014). Between 1980 and 2012, world aquaculture production volume increased at an average rate of 8.6 percent per year. World food fish aquaculture production more than doubled from 32.4 million tonnes in University of Ghana http://ugspace.ug.edu.gh http://animalfrontiers.org/content/3/1/28.full#ref-29 http://animalfrontiers.org/content/3/1/28.full#ref-40 17 2000 to 66.6 million tonnes in 2012, with an estimated total value of US$137.7 billion (FAO, 2014). Of the 66.6 million tonnes of farmed food fish produced in 2012, two- thirds (44.2 million tonnes) were finfish species grown from inland aquaculture (38.6 million tonnes) and mariculture (5.6 million tonnes). When farmed aquatic algae (mostly seaweeds) are included, world aquaculture production in 2012 was 90.4 million tonnes, worth US$144.4 billion. FAO estimates that world food fish aquaculture production rose by 5.8 percent to 70.5 million tonnes in 2013, with production of farmed aquatic plants (including mostly seaweeds) being estimated at 26.1 million tonnes (FAO, 2014). By continent, annual aquaculture production growth was fastest in Africa (11.7 %) and Latin America and the Caribbean (10 %) in the first twelve years of the new millennium (FAO, 2014). When China is excluded, the expansion in farmed food fish production in the rest of Asia recorded an annual growth rate of 8.2 % from 2000 to 2012, which is significantly higher than in the periods 1980–1990 (6.8 %) and 1990–2000 (4.8 %). The annual growth rate in China, the single largest aquaculture producer, fell to an average of 5.5 % in the period 2000–2012, less than half that of 1980–1990 (17.3 %) and 1990–2000 (12.7 %). Europe and Oceania had the lowest average annual growth rates in the period 2000–2012 at 2.9 and 3.5 %, respectively. In sharp contrast to other regions, production in North America started to shrink gradually from 2005 and, by 2012, was lower than in 2000, owing to the production fall in the United States of America (FAO, 2014). Worldwide, 15 countries produced 92.7 percent of all farmed food fish in 2012, with Asia accounting for about 88 % of total production by volume. Cut to just over half a million tonnes by the 2011 tsunami, Japan’s aquaculture production recovered slightly to more University of Ghana http://ugspace.ug.edu.gh 18 than 0.6 million tonnes in 2012 (FAO, 2014). Production peaked at more than 0.6 million tonnes in both the United States of America and the Republic of Korea in 2004 and 2007, respectively. In 2012, their respective production levels were slightly more than 0.4 million tonnes and just less than 0.5 million tonnes. Farmed food fish production has been rising steadily among the other leading producers, except in Chile, where disease outbreaks in marine cage culture of Atlantic salmon hit production in 2009–2010 before recovery and further expansion in production in 2011–12 (FAO, 2014). World aquaculture production can be categorized into inland aquaculture and mariculture. Inland aquaculture generally use freshwater, but some production operations use saline water in inland areas (such as in Egypt) and inland saline-alkali water (such as in China). Mariculture includes production operations in the sea and intertidal zones as well as those operated with land-based (onshore) production facilities and structures (2014). More than 600 aquatic species are raised in captivity worldwide for production in a variety of farming systems and facilities of varying input intensities and technological sophistication, using freshwater, brackish water and marine water (FAO, 2014). However, the stage of development and the distribution of aquaculture production remain imbalanced in all regions. A few developing countries in Asia and the Pacific, SSA and South America have made considerable progress in aquaculture development in recent years and they are becoming significant or major producers in their respective regions (FAO, 2014). However, the disparity remains huge across the continents and georegions, University of Ghana http://ugspace.ug.edu.gh 19 as well as among countries of comparable natural conditions in the same region, with aquaculture in many of the least developed countries yet to make a significant contribution to national food and nutrition security. World aquaculture production is vulnerable to adverse impacts of natural, socioeconomic, environmental and technological conditions (FAO, 2012a, WWF, 2012). In 2010, aquaculture in China suffered production losses of 1.7 million tonnes (worth US$3.3 billion) caused by diseases (295 000 tonnes), natural disasters (1.2 million tonnes), pollution (123 000 tonnes) etc. Disease outbreaks virtually wiped out marine shrimp farming production in Mozambique in 2011 (WWF, 2012). Total aquaculture production in Africa in 2012 was estimated to be 1 485 367 mt which is about 2.23 % of global production by volume. North Africa contributed about 1 030 675 mt whilst SSA contributed about 454 691 mt accounting for 69.39 and 30.61 % respectively of African production (FAO, 2014). Aquaculture production in SSA is dominated by Nigeria contributing about 15.57 % with the other top five producers (Uganda, Kenya, Zambia, Ghana and Madagascar) together contributing about 10.43 % of the total production in 2010. Between 2000 and 2010, overall aquaculture production in SSA increased by 84.52 % from 55 690 mt to 359 790 mt (FAO, 2012a). More than 70 % of total aquaculture production in SSA comes from commercial farms, produced by less than 20 % of farmers, whilst the remaining less than 30 % is produced by small-scale farmers that represent over 80 % of all farmers (Hecht, 2007). The systems used by the commercial sector range from semi-intensive to intensive pond, cage and tank culture of University of Ghana http://ugspace.ug.edu.gh 20 catfish (Clarias spp.) and tilapia (Oreochromis spp.) and high-valued products such as shrimp (Madagascar and Mozambique) and abalone (South Africa) while noncommercial subsistence aquaculture primarily consists of small-scale pond culture of tilapia, catfish and common carp, Cyprinus carpio (Hecht, 2007). Machena and Moehl (2001) reported that the major aquaculture products in Africa are mainly fresh- and brackish-water finfish. The share of freshwater aquaculture production in Africa increased from 21.8 percent in the 1990s to 39.5 percent in 2010 as a result of rapid development in freshwater fish farming in Nigeria, Uganda, Zambia, Ghana and Kenya (FAO, 2012a). African aquaculture production is mainly finfishes (99.3 percent by volume), with only a small fraction from marine shrimps (0.5 percent) and marine molluscs (0.2 percent). In spite of some limited successes, the potential for bivalve production in marine waters remains almost completely unexplored. In Ghana, aquaculture became important in the 1980’s when the Government of Ghana (GoG) recognized fish farming as an assured way of meeting the deficit in Ghana's protein requirements (GFAR, 2011). Due to massive GoG support, fish farming became established in many parts of the country. However, the growth of the sector was slow due in part to the subsistence nature of fish farming, inefficient and inappropriate production practices, and dependency on government support. In addition, the sector faced many challenges including lacking inputs such as fingerlings and fish feed produced commercially to support the growth of the industry (GFAR, 2011). University of Ghana http://ugspace.ug.edu.gh 21 Commercial fish farming in Ghana is a recent development that has been adopted in the past few years. Presently, there are about seven main commercial aquaculture farms operating in Ghana and over 200 medium/small-scale fish farms. In the last five years aquaculture production has increased by 80 percent from 2005 to 2010 as a result of proliferation of commercial fish farming particularly the cage farming on the Lake Volta (GFAR, 2011). Tilapia constitutes about 80 % of aquaculture production while catfish and others account for the remaining 20 %. While there is no major shrimp/prawn farming in Ghana yet, research shows that there is a great potential for commercial farming of local shrimp species (GFAR, 2011). The majority of the aquaculture operators grows or culture fish in earthen ponds either as a monoculture of tilapia or poly-culture of tilapia with catfish. Cage fish farms contribute over 80 percent of total fish yield in aquaculture production. The commercial operators do not produce their own fish feed but buy high quality pelletized balanced feed from animal feed companies (GFAR, 2011). Most medium/small-scale fish farmers do not produce their own fingerlings, instead they buy from the large scale farmers; others collect old stocks from other fish ponds or from rivers and streams. Tilapia fingerlings used on most medium/small-scale fish farms are mostly of poor quality (GFAR, 2011). The small/medium-scale operators produce various species of tilapia and catfish. Most small/medium-scale fish farmers rely on the natural productivity of the ponds to achieve their production. Others use agricultural by products, or poor quality feedstuffs in unbalanced proportions to feed tilapia. University of Ghana http://ugspace.ug.edu.gh 22 2.4 Aquaculture Growth and Fish Feeding In 2012, global aquaculture production totalled 90.4 million tonnes, made up of 66.6 million tonnes of food fish (i.e. finfishes, crustaceans, molluscs, amphibians, freshwater turtles, sea cucumbers, sea urchins, sea squirts and edible jellyfish) and 23.8 million tonnes of aquatic algae (mostly seaweeds) (FAO, 2014). Farmed food fish contributed 42.2 % of the total 158 million tonnes of fish produced by capture fisheries (including for non-food uses) and aquaculture in 2012. This compares with just 13.4 % in 1990 and 25.7 % in 2000 (FAO, 2014). Asia as a whole has been producing more farmed fish than wild catch since 2008, and its aquaculture share in total production reached 54 % in 2012, with Europe at 18 % and other continents at less than 15 %. FAO estimates in 2012 indicated that about 46.1 million tonnes (69.2 percent of total global aquaculture production including aquatic plants) of fish and crustaceans were feed-dependent, either as farm- made aquafeeds or as industrially manufactured compound aquafeeds (FAO, 2014). Continuing its established trend, the share of fed species in total farmed food fish production increased further from 66.5 % in 2010 to 69.2 % in 2012, reflecting a relatively stronger growth in the farming of fed species (FAO, 2014). While more than 200 species of fish and crustaceans are currently believed to be fed on externally supplied feeds, just 8 species or species groups account for 62.2 percent of the total feed used. These are: grass carp, common carp, Nile tilapia, Indian major carps (catla and rohu), whiteleg shrimp, crucian carp, Atlantic salmon, and pangasiid catfishes. More than 67.7 percent of farmed fed fish production is contributed by freshwater fishes, University of Ghana http://ugspace.ug.edu.gh 23 including carps and other cyprinids, tilapias, catfishes and miscellaneous freshwater fishes (FAO, 2012a). 2.5 Production and Use of Fish Feed Compound aquafeeds are used for the production of both lower-value (in marketing terms) food fish species, such as non-filter-feeding carps, tilapias, catfishes and milkfish, as well as higher-value species, such as marine finfishes, salmonids, marine shrimps, freshwater eels, snakeheads and crustaceans (FAO, 2012a). Globally, 708 million tonnes of industrial compound animal feeds were produced in 2008, of which 29.2 million tonnes were aquafeeds (4.1 percent of all animal feeds). As animal production has increased, so has global industrial compound animal feed production – almost fourfold from 7.6 million tonnes in 1995 to 29.2 million tonnes in 2008, at an average rate of 11 percent per year (FAO, 2012a). Production is expected to grow to 51.0 million tonnes by 2015 and to 71.0 million tonnes by 2020. While there is no comprehensive information available on the global production of farm- made aquafeeds (De Silva and Hasan, 2007), the estimate is that it was between 18.7 million and 30.7 million tonnes in 2006. More than 97 percent of carp feeds used by Indian farmers are farm-made aquafeeds (7.5 million tonnes in 2006/07), and they are the mainstay of feed inputs for low-value freshwater fishes in many other Asian and sub- Saharan countries. University of Ghana http://ugspace.ug.edu.gh 24 2.6 Feed Ingredient Production and Availability Feed ingredients used for the production of aquafeeds are broadly categorized into three types depending upon their origin: animal nutrient sources (including both aquatic and terrestrial animals); plant nutrient sources; and microbial nutrient sources (Tacon et al., 2012). 2.6.1 Animal Nutrient Sources The major aquatic animal protein meals and lipids used in aquafeeds include: fish/shellfish meals and oils; fish/shellfish by-product meals and oils; and zooplankton meals and oils (FAO, 2012a). The major terrestrial animal protein meals and lipids commonly used in aquafeeds are: (i) meat by-product meals and fats; (ii) poultry by- product meal, hydrolysed feather meal and poultry oil; and (iii) blood meals (Tacon et al., 2011). In recent years, increasing volumes of fishmeal and fish oil have originated from fisheries by-products (capture fisheries and aquaculture). An estimated 6 million tonnes of trimmings and rejects from food fish are currently used for fishmeal and fish-oil production (Tacon et al., 2011). Although some marine zooplanktons have potential for use as feed ingredients for aquaculture, commercial operations only exist for Antarctic krill (Euphausia superba), with total landings of 118 124 tonnes in 2007 (Tacon et al., 2011). Although krill meal and krill oil are available, information concerning their total global production and market availability is currently unavailable. Processed animal protein ingredients (often referred to as land animal products) such as blood meal, feather meal and poultry by-product meal are comparable with many other University of Ghana http://ugspace.ug.edu.gh 25 protein sources used in fish feeds on a cost-per unit protein basis (NRC, 2011). No effects on growth performance and feed utilization were observed when fish meal protein in finfish diets was replaced with 60˗80% of poultry by-products (PBM) or with 30˗40% hydrolysed feather meal (FeM) (Yu, 2008). A number of published reports are available regarding the suitability of different animal protein feeds as alternatives to fish meal in fish feeds (Rossi Jr and Davis, 2012; Hernández et al., 2010; El-Haroun et al., 2009; Rawles et al., 2009; Hu et al., 2008; Saoud et al., 2008; Wang et al., 2008; El-Sayed, 1998). 2.6.2 Plant Nutrient Sources The major plant dietary nutrient sources used in aquafeeds include: cereals, including by- product meals and oils; oilseed meals and oils; and pulses and protein concentrate meals (Tacon et al., 2011). Total global cereal production was 2 489 million tonnes in 2009, with maize totalling 817.1 million tonnes (32.8 percent of the total), followed by wheat, rice paddy, and barley. In 2009, oilseed production was 415 million tonnes, with soybean being the largest and fastest-growing oilseed crop and accounting for slightly more than 50 percent (210.9 million tonnes) of this total. Among the pulses, protein concentrate meals from peas and lupins are commercially available for use within compounded animal feeds, including aquaculture feeds. Using plant-based proteins in aquaculture feeds requires that the ingredients possess certain nutritional characteristics, such as low levels of fibre, starch and anti-nutritional compounds. They must also have a relatively high protein content, favourable amino acid University of Ghana http://ugspace.ug.edu.gh 26 profile, high nutrient digestibility and reasonable palatability (NRC, 2011; Lim et al., 2008). A number of previous studies discuss the suitability of plant protein feeds and/or local agricultural by-products as an alternative protein source in fish feeds (Burr et al., 2012; Bonaldo et al., 2011; Brinker and Reiter, 2011; Cabral et al., 2011; Nyina- Wamwiza et al., 2010; Pratoomyot et al., 2010; Garduño-Lugo and Olvera-Novoa, 2008; Olsen et al., 2007). Duckweeds grown on water with 10-30 mg NH3-N/litre have high protein content (around 40%) of high biological value (Hillman and Cully, 1978). Fresh duckweed is highly suited to intensive fish farming systems with relatively rapid water exchange for waste removal (Gaigher et al., 1984) and duckweed is converted efficiently to live weight by certain fish including carp and tilapia (Hasan and Edwards, 1992; Robinette et al 1980; Hepher and Pruginin, 1979; Van Dyke and Sutton, 1977). A duckweed lagoon with a standing crop of duckweed is harvested and placed fresh into a second lagoon containing a mixed size tilapia culture. The pond is harvested twice weekly and the fish sorted into various groups for return to the lagoon or sale. Under these circumstances the average yield of fish per hectare of lagoon is estimated at around 10 tonnes annually using only duckweed as the supplement to the naturally available fish feed (Skillicorn et al., 1993). 2.6.3 Microbial Ingredient Sources Microbial-derived feed ingredient sources for aquafeed include algae, yeasts, fungi, bacteria and/or mixed bacterial/microbial single-cell protein sources (Tacon et al., 2011). University of Ghana http://ugspace.ug.edu.gh 27 The only such sources available in commercial quantities globally are yeast-derived products, including brewer’s yeast and extracted fermented yeast products, but with limited information concerning their total global production and availability (FAO, 2012a). Given the relatively low cost of some of these single-cell proteins, they are probably most relevant as a major protein ingredient in fish feed or may at least partially replace fishmeal in feeds for some fish species (FAO, 2012a). Various species of macroalgae and microalgae have been incorporated into fish feed formulations to assess their nutritional value, and many have been shown to be beneficial: Chlorella or Scenedesmus fed to Tilapia (Tartiel et al., 2008); Chlorella fed to Korean rockfish (Bai et al., 2001); Undaria or Ascophyllum fed to Sea Bream (Yone et al., 1986); Ascophyllum, Porphyra, Spirulina, or Ulva fed to Sea Bream (Mustafa and Nakagawa, 1995); Gracilaria or Ulva fed to European Sea Bass (Valente et al., 2006); Ulva fed to Striped Mullet (Wassef et al., 2001); Ulva or Pterocladia fed to Gilthead Sea Bream (Wassef et al., 2005); Porphyra or a Nannochloropsis-Isochrysis combination fed to Atlantic Cod (Walker et al., 2009, 2010). Unfortunately, it has rarely been possible to determine the particular nutritional factors responsible for these beneficial effects, either because no attempt was made to do so or poor design of the study. For example, in one of the few studies that has focused on the effects of substituting algal protein for gluten protein, the control and all the test diets contained casein plus added methionine and lysine, no analysis of the algal protein was provided, and the algal protein (a biofuel process by-product) contained very high levels of aluminium and iron (Hussein et al., 2012). University of Ghana http://ugspace.ug.edu.gh 28 2.7 Anti-nutrients in Feed Ingredients The use of plants or plant-derived feedstuffs such as legume seeds, different types of oilseed cake, leaf meal, leaf protein concentrates and root tuber meals as fish feed ingredients is limited by the presence of a wide variety of anti-nutritional substances (Francis et al., 2001) (Table 2.1). However, only a few are of major importance for fish feed formulation. The effects of these substances on fish can include reduced palatability, altered nutrient balance of the diet, disturbance of digestive processes and growth, decreased feed efficiency, pancreatic hypertrophy, hypoglycaemia, liver dysfunction, goiterogenesis and immune suppression (NRC, 2011; Krogdahl et al., 2010). It has been observed that common processing techniques, such as cooking, soaking, drying and wet heating, as well as adding feed supplements, can reduce the concentration of anti-nutritional factors in plant feeds and improve the feed intake (Rehman and Shah, 2005; Francis et al., 2001; Alonso et al., 2000). By-products of animal origin may also contain anti-nutritional compounds, especially if the products are not properly preserved or processed (NRC, 2011). However, whilst some anti-nutritional factors are easy to eliminate by processing, others may be more difficult to eliminate. University of Ghana http://ugspace.ug.edu.gh 29 Table 2.1 Anti-nutrient compounds and their biological effects on animals Compound Biological effects References Fibres Interfere with digestion, absorption and utilization of macro- and micro- nutrients. Van Der Kamp et al. (2004) Phytic acid Impairs mineral digestion and contains phosphorus in a form unavailable to monogastrics. Thompson (1993) Protease inhibitors Growth reduction, inhibition of proteolytic enzymes. Francis et al. (2001) Enzyme inhibitors Reduce the digestion of protein, carbohydrates and lipids. Thompson (1993); Krogdah and Holm (1979) Goitrogen Growth reduction, thyroid hyperplasia, changes in T3 and T4 levels. Francis et al. (2001) Oestrogens Growth reduction, induction of vitellogenin secretion. Francis et al. (2001) Lectins Make the gut more permeable for increased influx of macromolecules and bacteria, stimulate insulin production and alter metabolism. Growth reduction. Grant (1991) Saponins Interfere with lipid and protein digestion. Growth and feed efficiency reduction. Cuadrado et al. (1995) Glucosinolates Reduce the uptake of iodine into the thyroid gland and may lead to goitre. Liener (1980) Cyanogens Respiratory failure. Growth and feed efficiency reduction. Liener (1980) Phytoestrogens Interfere with endogenous oestrogen. Price and Fenwick (1985) Phytosterols Interfere with cholesterol absorption and metabolism. Ostlund Jr et al. (2003) Quinolizidine alkaloids Lupine alkaloids, may cause nervous symptoms and intestinal disorders. Wink et al. (1998) Oligosaccharides Alter the microbiota in the gut and increase osmotic pressure in the intestine. Cummings et al. (1986) Alkaloids Growth and reduced feed palatability, liver abnormalities. Francis et al. (2001) Anti-vitamins Reduced vitamin availability. Melcion and Poel (1993) Toxic fatty acids Effect on reduction mortality. Liener (1980) Data source: Adapted from Hardy (2010); Krogdahl et al. (2010); Francis et al. (2001); Melcion and Poel (1993). University of Ghana http://ugspace.ug.edu.gh 30 2.8 Culturing of Tilapia “Tilapia” is a generic term which is used to designate a group of commercially important food fish belonging to the family Cichlidae. Tilapia have been raised as food for human consumption for a long time; illustrations from Egyptian tombs suggest that the Nile tilapia, Oreochromis niloticus, was cultured more than 3000 years ago (Maar et al., 1966). Tilapia is referred to as “Saint Peter’s fish” in reference to biblical passages about the fish fed to the multitudes (Popma and Masser, 1999). Although endemic to Africa their distribution has been extended by introduction to include much of the tropics and subtropics. More than 100 species have been identified (Balarin, 1979). Currently, tilapia culture is widely practised in many tropical and subtropical regions of the world. More than 22 tilapia species are being cultured worldwide. However, Nile tilapia (Oreochromis niloticus), Mozambique tilapia (O. mossambicus), blue tilapia (O. aureus), O. hornorum, O. galilaeus, Tilapia zillii and T. rendalli are the most commercially cultured tilapia species (Fitzsimmons, 2000). Tilapia species are used in commercial farming systems in almost 100 countries and are developed to be one of the most important fish for aquaculture in this century. 2.9 Reproduction in Nile Tilapia Sexual maturity of Nile tilapia is reached at 10-30 cm total length (TL) and is related to the maximum size attained in a given population and condition, which in turn is determined by food availability and temperature (Trewavas, 1983; Pullin and Lowe- McConnell, 1982). Reproduction occurs only when temperature exceeds 20 °C. The breeding cycle is latitude dependent and spawning becomes more seasonal at higher University of Ghana http://ugspace.ug.edu.gh 31 latitudes. In many instances the breeding cycle is synchronized with the rainy season (Trewavas, 1983). The species is a nest building, batch spawning mouth brooder that can spawn every 30 days. The nest, like in many tilapiine fishes, is a circular depression in sandy areas of up to 1m in diameter and 0.5 m deep. The average nest diameter is twice the length of the male making it. Males are highly territorial and defend their nests (Trewavas, 1983). Batches of eggs are spawned into the nest, fertilized externally and then picked up by the female. The female incubates the eggs for 5-7 days when they hatch and the early fry remain in the mouth until after yolk sac absorption. Depending on size, females can carry up to 200 eggs. The eggs are large and ovoid (pear shaped) and at hatching the fish are around 4 mm in length (Trewavas, 1983). 2.10 Natural Food and Feeding Habits of Nile Tilapia Early juveniles and young fish are omnivorous, feeding mainly on zooplankton and zoobenthos but also ingest detritus and feed on aufwuchs and phytoplankton (Beveridge, 2000; Moriarty and Moriarty, 1973; Moriarty et al., 1973). At about 6 cm TL the species becomes almost entirely herbivorous feeding mainly on phytoplankton, using the mucus trap mechanism and its pharyngeal teeth. The pH of the stomach varies with the degree of fullness and when full can be as low as 1.4, such that lysis of blue-green and green algae and diatoms is facilitated (Moriarty, 1973). Enzymatic digestion occurs in the intestine where pH increases progressively from 5.5 at the exit of the stomach to 8 near the anus. Nile tilapia exhibits a dual feeding pattern. Ingestion occurs during the day and digestion occurs mainly at night (Trewavas, 1983). The digestive tract of Nile tilapia is at least six times the total length of the fish, providing abundant surface area for digestion and University of Ghana http://ugspace.ug.edu.gh 32 absorption of nutrients from its mainly plant-based food sources (Opuszynski and Shireman, 1995). 2.11 Growth of Nile Tilapia A study on the growth of 10 populations of O. niloticus under natural conditions showed that the von Bertalanffy growth function parameters range as follows: L∞ (cm) = 22.9 to 57.2, K = 0.14 to 0.51 and to = -0.85 to 0.54 (Merona et al., 1988). The maximum recorded size is 64 cm TL (Lake Kyoga) and in Lake Turkana fish of up to 7 kg have been recorded (Trewavas, 1983). The range of von Bertalanffy growth function parameters for cultured Nile tilapia as modelled by Moreau and Pauly (1999) were: L∞ (cm) = 16.6 to 41.8, K = 0.637 to 4.566 and Ø’ = 2.93 to 3.43. The wide range of values reported for Nile tilapia under natural conditions reflects the phenotypic response to the prevailing environmental conditions of the species and under culture condition is determined by sex ratio, stocking density, culture systems, feeds, temperature and water quality (Abdel-Tawwab and El-Marakby, 2004). Several organizations have invested substantial resources in the genetic improvement of Nile tilapia. The Genetically Improved Farmed Tilapia (GIFT) strains developed by the WorldFish Center as well as other strains (GET EXCEL, GenoMar ASA and GenoMar Supreme Tilapia) have significantly better growth performance than “unaltered” strains (Asian Development Bank, 2005). University of Ghana http://ugspace.ug.edu.gh 33 2.12 Use of Formulated Feeds for Nile Tilapia High quality formulated feeds are used to achieve high yields and large sized fish (600- 900 g) within a short period of time (Dey, 2001). Under semi-intensive farming systems, most tilapia farmers in Asia fertilize their ponds and use formulated feeds. However, in intensive pond and tank culture systems or in cages, tilapia farmers mainly depend on commercial pelleted feeds. In terms of pond yields, Dey (2001) reported that overall, the average yield of pond farming in Taiwan, Province of China is very high (12 to 17 tonnes/ha) while ponds in Bangladesh, China, the Philippines, Thailand and Vietnam produce around 1.7, 6.6, 3.0, 6.3 and 3.0 tonnes/ha, respectively. Tilapia feeds accounted for about 8.1 percent of global aquafeed production in 2003 (Tacon et al., 2006). Commercial tilapia feeds are mainly dry sinking pellets and extruded floating pellets. Production estimates for farm-made tilapia feeds are not available as these are usually site specific and dependent on locally available feed ingredients (Tacon et al., 2006). In countries such as the Philippines, on-farm feeds are not very popular as tilapia farmers find it more convenient to purchase formulated feeds from feed companies. The main issue in formulating feed is to meet the protein and essential amino acids (EAAs) requirements of the species to facilitate tissue/muscle growth. Fishmeal is generally the preferred protein source because of the high quality of the protein and its EAA profile (Jauncey and Ross, 1982). However, fishmeal is generally expensive and is not always available. Nile tilapia can be fed with a high percentage of plant proteins (Mbahinzireki et al., 2001; Ofojekwu and Ejike, 1984). It is economically judicious to University of Ghana http://ugspace.ug.edu.gh 34 replace fishmeal with alternative protein sources including animal by-products, oilseed meal and cakes, legumes and cereal by-products and aquatic plants (Agbo et al., 2011; Rumsey, 1993). Most of these ingredients are deficient in some EAA and hence require supplementation or be compensated with other feedstuffs. Although most of the oilseed cakes/by-products are generally deficient in lysine and methionine, blending of different oilseed cakes often provides balanced amino acid profile (Lim and Webster, 2006). However, they contain many anti-nutritional factors (such as gossypol, glucosinolates, saponins, trypsin inhibitors etc.) which limit their use in compound feeds or require removal/inactivation through specific processing (such as heating, cooking etc.) (NRC, 1993). There are also several non-conventional protein sources that may be suitable for O. niloticus such as silkworm pupae, snails, earthworms, Spirulina, corn and wheat gluten, almond cake, sesame cake, brewery waste etc. 2.13 Feeding Schedules (Rates and Frequencies) for Cultured Tilapia Feeding rate (allowance) in practical feeding of fish involves two options. One is to feed the fish to satiation (i.e. Ad libitum) and the other is to feed a restricted ration (Suresh, 2003). Best growth is normally achieved by feeding to satiation. However, satiation levels are not necessarily the most economic feeding levels, as food conversion at satiation levels is often poor. This may also lead to overfeeding, which is wasteful and deleterious to water quality. As a result, restricted rations are recommended for feeding fish (Suresh, 2003). It is also common practice to feed to satiety before determining the rate of feeding. It is generally known that smaller fish consume more feed per unit body weight compared to larger fish. Tilapia is known to consume less feed during the colder University of Ghana http://ugspace.ug.edu.gh 35 months of the year in countries where there are substantial seasonal temperature fluctuations. Some recommended feeding schedules widely used for semi-intensive and intensive culture for tilapia in freshwater ponds in China are shown in Table 2.2 (Miao and Liang, 2007). Table 2.2 Feeding schedules for various sizes of tilapia in semi-intensive and intensive culture in freshwater ponds Fish size (g) <1 Feeding rate (% wet body weight) Feeding frequency Semi-intensive (<20 000/ha) Intensive (>20 000/ha) (No./day) 30-10 - To satiation 1 to 5 10 to 6 - 6 5 to 20 6 to 4 - 4 20-100 4 to 3 - 4 100-250 3 - 3 250-500 3 to 2 2.0-1.5 3 >500 2-1.5 1.5-1.3 3-2 Source: Adapted from Miao and Liang (2007) 2.14 Nutritional Requirements of Nile Tilapia Nutritional requirements of fish differ for different species and more importantly vary with life stage. Fry and fingerlings require diets with higher protein, lipids, vitamins and minerals and lower carbohydrates as they are developing muscle, internal organs and bones with rapid growth (Fitzsimmons, 1997). From various studies the protein requirements of juvenile tilapia have been reported to range between 30-56% (Agbo, 2008; Suresh, 2003; Jauncey, 1998). Protein requirements of Nile tilapia for optimum growth are dependent on dietary protein quality/source, fish size or age and the energy contents of the diets and have been reported to vary from as high as 45-50 percent for first feeding larvae, 35-40 percent for fry and fingerlings (0.02-10 g), 30-35 percent for juveniles (10.0-25.0 g) to 28-30 percent University of Ghana http://ugspace.ug.edu.gh 36 for on-growing (>25.0 g) (El-Sayed , 2006; Lim and Webster, 2006; Fitzsimmons, 2005; Shiau, 2002) (Table 2.3). The broodfish require about 40-45 percent protein for optimum reproduction, spawning efficiency and for larval growth and survival. Nile tilapia requires the same ten essential amino acids (EAAs) as other finfishes. The recommended EAAs for Nile tilapia are shown in Table 2.4 below: Table 2.3 Dietary protein needs for Nile tilapia, O niloticus by life stage Life stage Weight (g) Dietary protein content (%) First feeding larvae 45-50 Fry 0.02-1.0 40 Fingerlings 1.0-10.0 35-40 Juveniles 10.0-25.0 30-35 Adults 25.0-200.0 30-32 >200 28-30 Broodstock 40-45 Data source: El-Sayed (2006), Lim and Webster (2006), Fitzsimmons (2005), Shiau (2002) Table 2.4 Essential amino acid needs of Nile tilapia, O. niloticus as % of dietary protein and of total diet Amino acid % of protein % of diet Arginine 4.20 1.18 Histidine 1.72 0.48 Isoleucine 3.11 0.87 Leucine 3.39 0.95 Lysine 5.12 1.53 Methionine 2.68 a 0.75 Phenylalanine 3.75 b 1.05 Threonine 3.75 1.05 Tryptophan 1.00 0.28 Valine 2.80 0.78 (a) In the presence of cystine at 0.54% of dietary protein. Total sulphur amino acid (methionine plus cystine) requirement is 3.21% of the protein (b) In the presence of tyrosine at 1.79% of dietary protein. Total aromatic amino acid (phenylalanine plustyrosine) requirement is 5.54% of the protein Data source: El-Sayed (2006), Lim and Webster (2006), Fitzsimmons (2005), Shiau (2002) The minimum requirement of dietary lipids in tilapia diets is 5 percent but improved growth and protein utilization efficiency has been reported for diets with 10-15 percent lipids (Ng and Chong, 2004). Both n-3 and n-6 polyunsaturated fatty acids (PUFAs) University of Ghana http://ugspace.ug.edu.gh 37 have been shown to be essential for maximal growth of hybrid tilapia (O. niloticus x O. aureus). For Nile tilapia the quantitative requirement for n-6 PUFA is around 0.5-1.0 percent. Unlike marine fish species, tilapia appear not to have a requirement for n-3 highly unsaturated fatty acids (HUFAs) such as EPA (20:5n-3) and DHA (22:6n-3) and its n-3 fatty acid requirement can be met with linolenic acid (18:3n-3). The recommended crude lipid, essential fatty acids and energy for Nile tilapia are shown in Table 2.5 below: Table 2.5 Crude lipid, essential fatty acids and energy needs for growth of O. niloticus (% dry feed) Nutrient Amount Crude lipid, % min. 10-15 Essential fatty acids, % min. 18:2n-6 0.5-1.0 a 20:4n-6 1.0 a 18:3n-3 20:5n-3 22:6n-3 Carbohydrate, % max b 40 Crude fibre, % max 8-10 Protein to energy ratio 110 c (mg/kcal) 120 d (a) 1% 20:4n-6 or 0.5-1% 18:2n-6. (b) Dieatry utilization of carbohydrate appear to decrease with decrease in fish size (c) mg protein for kcal of gross energy (GE); (d) mg protein for kcal of digestible energy (DE) Data source: El-Sayed (2006), Lim and Webster (2006), Fitzsimmons (2005), Shiau (2002) Carbohydrates are included in tilapia feeds to provide a cheap source of energy and for improving pellet binding properties. Tilapia can efficiently utilize as much as 35-40 percent digestible carbohydrate (El-Sayed, 2006). Nile tilapia is capable of utilizing high levels of various carbohydrates of between 30 to 70 percent of the diet. It has also been demonstrated that larger hybrid tilapia (O. niloticus x O. aureus) utilized carbohydrates better than smaller sized fish. Older fish seem to cope with higher dietary fibre content, a University of Ghana http://ugspace.ug.edu.gh 38 maximum of 8-10 % (El-Sayed, 2006; Lim and Webster, 2006; Jauncey, 1998) and younger ones at about 6-8 % (Fitzsimons, 2005; Shiau, 2002). Table 2.6 Mineral requirements of O. niloticus (% of dry feed except otherwise mentioned) Minerals Amount Macro elements (%) Calcium, max. 0.7 a Phosphorus, min. 0.8-1.0 Magnesium, min. Sodium, min. 0.06-0.08 Potassium 0.21-0.33 b Microelements, min mg/kg dry diet Iron 60 Sulphur Chlorine Copper 2-3 Manganese 12 Zinc 30-79 Cobalt Selenium 0.4 Iodine 1.0 Molybdenium Chromium 139.6 b Fluorine a Based on data from O. aureus; b Based on data from hybrid tilapia (O. niloticus X O. aureus). Data source: Shiau (2002), Fitzsimmons (2005), El-Sayed (2006), Lim and Webster (2006) There is little information on the mineral requirements of tilapia. Like other aquatic animals, tilapias are able to absorb minerals from the culture water which makes the quantitative determination of these elements difficult to carry out (Stickney, 1997). Despite its ability to absorb minerals from the culture water and the presence of minerals in feed ingredients, tilapia feeds should contain supplemental mineral premixes. This is to ensure that sufficient levels are available to protect against mineral deficiencies caused by reduced bioavailability such as when plant phosphorus sources are used in tilapia feeds University of Ghana http://ugspace.ug.edu.gh 39 (Shiau and Su, 2003). The mineral requirements of Nile tilapia as percentage of dry feed is shown in Table 2.6 above. Table 2.7 Vitamin needs of O. niloticus (% of dry feed except otherwise mentioned) Vitamin Amount Vitamins, min IU/kg dry diet Vitamin A (Retinol) 5 000 Vitamin D (Cholecalciferol) 3.75 b Vitamin, min mg/kg dry diet Vitamin E (α-tocopherol) 50-100 c Vitamin K 4.4 Vitamin B1 (Thiamine) 4 Vitamin B2 (Riboflavin 5-6 d Vitamin B3 (Niacin/nicotinic acid) 26-121 b Vitamin B5 (Pantothenic acid) 10 a Vitamin B6 (Pyridoxine) 1.7-9.5 e Vitamin B9 (Folic acid) 0.5 Vitamin B12 (Cyanocobalamin acid) Not required Choline 1 000 b Inositol 400 b Vitamin B7 (Biotin) 0.06 c Vtamin C (Ascorbic acid) 420 a Based on data from O. aureus; b Based on data from hybrid tilapia (O. niloticus X O. aureus). c Based on diets with 5% lipid. Vitamin E requirement increases to 500 mg/kg dry diet at 10-15% dieatry lipid level; d Based on data from hybrid tilapia (O. mossambicus X O. niloticus) and O. aureus e Based on data from hybrid tilapia (O. niloticus X O. aureus) at dietary protein level of 28%, requirement 15-16.5 mg/kg diet at 36% protein diet Data source: Shiau (2002), Fitzsimmons (2005), El-Sayed (2006), Lim and Webster (2006) Vitamin supplementation is not necessary for tilapia in semi-intensive farming systems, while vitamins are generally necessary for optimum growth and health of tilapia in intensive culture systems where limited natural foods are available (El-Sayed, 2006; Lim and Webster, 2006). The vitamin requirements of Nile tilapia as percentage of dry feed is shown in Table 2.7 above. University of Ghana http://ugspace.ug.edu.gh 40 2.15 Nutritional Deficiencies in Nile Tilapia Deficiency signs of farmed tilapia may occur when fish are fed nutrient deficient diets or raised in a low nutrient-input culture system (Dabrowska et al., 1989). Essential amino acid (EAA) deficiency in tilapia generally leads to loss of appetite, retarded growth, and poor feed utilization efficiency (Table 2.8). Table 2.8 Dietary nutritional deficiency of essential amino acid and essential fatty acid EAAs/EFA Deficiency signs/syndrome EAAs Lysine Dorsal/caudal fin erosion, retarded growth, increased mortality Methionine Retarded growth, cataract Tryptophan Retarded growth, scoliosis, lordosis, caudal fin erosion Essential fatty acid Linoleic acid (18:2n-6) Retarded growth, swollen pale liver, fatty liver In bold: Reported EFA deficiency signs for O. niloticus, not in bold: general EAA deficiency symptoms in fish Data source: Tacon (1987), Tacon (1992) In some fish species (e.g. rainbow trout, sockeye salmon, Atlantic salmon, chum salmon, coho salmon), lysine, methionine or tryptophan deficiency results in various signs such as scoliosis, lordosis, fin erosions and cataracts although none of these deficiency signs have been reported for tilapias (Tacon, 1987). Similar to EAA deficiency, the lack of essential fatty acids (EFA) will also lead to loss of appetite and poor growth in tilapia. Other reported signs of EFA deficiencies in Nile tilapia include swollen pale and fatty livers (Tacon, 1992). Mineral deficiencies are difficult to assess in tilapia as most trace elements are obtained both from the dietary ingredients and from the culture water (Dabrowska et al., 1989). Table 2.9 below shows the dietary nutritional deficiencies of some minerals in fish. University of Ghana http://ugspace.ug.edu.gh 41 Table 2.9 Dietary mineral deficiency signs and symptoms associated with tilapia species Minerals Deficiency signs/syndrome Phosphorus Lordosis, poor growth Calcium Reduced growth, poor feed conversion and bone mineralization Potassium Reduced growth and feed efficiency, anorexia, convulsions Magnesium Reduced growth/whole-body hypercalcinosis Iron Microcytic, homochronic anaemia Zinc Reduced growth and appetite, cataracts, high mortality, erosion of fins and skin, short body dwarfism, fin erosion Manganese Reduced growth and skeletal abnormalities, anorexia, loss of equilibrium Copper Reduced growth, cataracts Selenium Increased mortality, muscular dystrophy, reduced growth, cataracts, anaemia Iodine Thyroid hyperplasia (goitre) In bold: Reported deficiency signs for O. niloticus, Not in bold: general mineral deficiency symptoms in fish Data source: Chow and Schell (1980), Tacon (1987), Tacon (1992), NRC (1993), Jauncey (2000) University of Ghana http://ugspace.ug.edu.gh 42 Table 2.10 Specific vitamin deficiencies associated with tilapia species Vitamins Species Deficiency signs/syndrome Vitamin B2 (Riboflavin) O. aureus Poor growth, high mortality, lethargy, fin erosion, anorexia, loss of body colour, dwarfism, cataracts Vitamin B5 (Pantothenic acid) O. aureus Poor growth, hyperplasia of epithelial cells of gill lamellae, fin erosion, haemorrhage, anaemia, sluggishness Vitamin B3 (Niacin/nicotinic acid) Hybrid tilapia (O. niloticus x O. aureus) Haemorrhage, deformed snout, gill oedema, and skin, fin, and mouth lesions Vitamin B1 (Thiamine) Hybrid tilapia (O. mossambicus x O. niloticus) and Nile tilapia Poor growth and poor feed efficiency, anorexia, light colouration, nervous disorders, low haematocrit and red blood cell count, and increased serum pyruvate Vitamin B6 (Pyridoxine) Hybrid tilapia (O. niloticus x O. aureus) Poor growth and poor feed efficiency, high mortality, abnormal neurological signs, anorexia, convulsions, caudal fin erosion, mouth lesion Vitamin B7 (Biotin) Hybrid tilapia (O. niloticus x O. aureus) Poor growth Folic acid Nile tilapia Poor growth, reduced feed intake and efficiency Vitamin B2 (Riboflavin) Nile tilapia Requirement not reported Choline Hybrid tilapia (O. niloticus x O. aureus) Poor growth and survival, and reduced blood triglyceride, cholesterol, and phospholipid concentration Inositol Nile tilapia Requirement not reported Vitamin C (Ascorbic acid) Nile tilapia Poor growth and poor feed efficiency, scoliosis, lordosis, poor wound healing, haemorrhage, fin erosion, anaemia exopthalmia and gill and operculum deformity Vitamin A (Retinol) Nile tilapia Poor growth and poor feed efficiency, restlessness, abnormal swimming, blindness, exophthalmia, skin, fin, and eye haemorrhages, pot-belly syndrome, reduced mucus, secretion, high mortality Vitamin D (Cholecalciferol) Hybrid tilapia (O. niloticus x O. aureus) Poor growth and poor feed efficiency, low haemoglobin, , reduced liver size Vitamin K Nile tilapia Requirement not reported Vitamin E (α-tocopherol) Nile tilapia Poor growth and poor feed efficiency, anorexia, skin and fin haemorrhage, muscle degeneration, depigmentation Data source: Jauncey (2000), El-Salyed (2006), Lim and Webster (2006) University of Ghana http://ugspace.ug.edu.gh 43 Under culture conditions, vitamin deficiency signs are not a common occurrence in tilapia (El-Sayed 2006; Lim and Webster 2006; Jauncey, 2000). In fact, several studies have reported on the “non-essentiality” of adding vitamin premixes to tilapia diets (Jauncey, 2000). Vitamins obtained from natural food in fertilized ponds, endogenous vitamins present in feed ingredients used in tilapia feeds and the microbial biosynthesis of some vitamins in the gut are all likely to contribute significantly to the vitamin requirements of tilapia. Table 2.10 shows the dietary nutritional deficiencies of some vitamins in fish. 2.16 Pond Culture Pond culture is a very popular aquaculture production method with many aquatic species cultured in ponds. To have successful pond production, ponds must be properly sited and built, with careful assessment of water availability, quantity, and quality. There are two main types of pond systems: watershed and levée systems (Whitis, 2002). The climate and topography of a region will determine which type of pond system is appropriate. Areas that have enough rainfall to fill and keep ponds filled will be more suited to watershed pond systems. In an area where the main water source is groundwater, then a levée pond may be more suitable (Whitis, 2002). Most commercially produced warm-water species, some cool-water species, and baitfish are typically reared in ponds (Tucker et al., 2002). In commercial pond culture, there is either some degree of fertilization or supplemental feeding to increase production to commercially viable levels, greater than would occur natura