Department of Marine and Fisheries Sciences

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    Evaluation of Nile Tilapia (Oreochromis Niloticus, Linnaeus 1758) Fingerling Production at the Aquaculture Demonstration Centre - Ashaiman, Ghana.
    (University of Ghana, 2018-07) Lutterodt, J.B.
    The Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) fingerling production is important for continual expansion of the global tilapia aquaculture. This study evaluated the Akosombo Strain Nile tilapia fingerling production at the Aquaculture Demonstration Centre- Ashaiman, Ghana. A total of 1350 female brooders of mean weight 150.7±41.8 g and 450 males of mean weight 218.6±63.1 g were stocked into nine outdoor concrete tanks of size 50 m2 each in a sex ratio of 3:1 respectively for 14 days. From the estimated 675,000 eggs produced by the females, a total of 138,631 fry were harvested resulting in 20.5% hatching success. The survival rate of the fry after hormonal treatment was 79.5% with estimated FCR of 1.46 and SGR of 6.05±0.35%day-1. For growth to the fingerling stage, the fry were stocked into an earthen pond of size 1200 m2 for 24 days at an initial weight of 0.23±0.04 g. The final mean weight of fingerlings harvested was 2.47±0.55 g with FCR of 1.09, SGR (3.26±0.18%day-1) and a survival rate of 75.3%. The estimated final standing crop was 1708.4 kg ha-1. Results from statistical analysis indicated that there were no significant differences among fry produced in the breeding tanks (p=0.73).Water quality measurements in the breeding tanks, fry tanks and fingerlings pond were respectively 29.03±0.51oC, 28.07±1.79oC and 27.07±1.68oC for temperature; 3.56±0.04 mgL-1, 3.62±0.18 mgL-1 and 3.74±0.21 mgL-1 for DO; 7.38±0.19, 7.35±0.18 and 7.56±0.25 for pH; salinity were 0.23±0.01‰, 0.24±0.02‰ and 0.29±0.02‰, and ammonia levels of 0.12±0.06 mgL-1, 0.01±0.002 mgL-1 and 0.04 ± 0.01 mgL-1 respectively. The study concludes that the Centre can increase production of fingerlings if the current management practice at the breeding stage of production is improved.
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    Evaluation of Larval Meal Diet of Black Soldier Fly (Hermetia Illucens: L. 175) On Fingerlings Culture of Nile Tilapia( Oreochromis Niloticus: L.)
    (2017-07) Teye-Gaga, C.
    The decreasing availability and increasing cost of fishmeal have called for efforts in evaluating wide varieties of relatively lower cost ingredients that could partially or wholly replace fishmeal. The Black Soldier Fly (BSF), Hermetian illucens larvae hold potential in this regard due to their high protein and fat contents. This study was conducted at the BSF Centre of the Ghana Atomic Energy Commission, Accra, and Aquaculture Research and Development Centre at Akosombo, to evaluate the growth performance of fingerlings of Oreochromis niloticus (Akosombo strain) using diets with BSF larval meal as an alternative source of protein to fishmeal and to determine the apparent digestibility of nutrients of BSF larval meal in comparison to those of traditional sources of protein, such as fishmeal and soybean meal. The BSF larvae were reared on fruit and vegetable wastes and then solar dried. The BSF larval meal was used to replace fishmeal at 25, 50 and 75% inclusion levels in formulated diets for O. niloticus fingerlings. Two other tilapia diets, an on-farm type (ARDEC) and a commercial one (RAANAN), containing 0% BSF larval meal served as controls. In all, five isonitrogenous (380 gkg-1 crude protein) and isoenergetic (18 kJg-1 gross energy) diets were used in culturing O. niloticus fingerlings (initial mean weight 1.3±0.23 g) for 10 weeks. Apparent digestibility coefficients (ADCs) were determined using chromic oxide as inert marker. The reference diet was formulated to contain 380 gkg-1 crude protein and 18 kJg-1 gross energy. The reference diet was replaced with test ingredients at 70:30 ratios. Proximate analysis on the whole BSF larvae was found to contain crude protein (37.83%) and crude fat (22.7%) (dry matter basis). All diets were readily accepted by fish. Growth and nutrient utilisation parameters of the cultured O. niloticus fingerlings indicated no significant differences (p > 0.05) among the various dietary treatments. BSF 25 had the highest final mean weight gain (33.82±2.53 g) and the least was BSF 75 (30.53±3.95 g). Whole-body observation of harvested fingerlings showed no abnormalities on the external and internal body. This suggests that BSF larval meal does not exert a negative effect on fish health. Analysis on the cost effectiveness of the various diets used in culturing O. niloticus fingerlings showed that producing a kilogram of fish using BSF 75 diet was more cost effective than other diets. Nutrient digestibility of BSF meal compared favourably with those of fishmeal and soybean meal. The apparent digestibility coefficients (ADCs) of nutrients of BSF meal, fishmeal and soybean meal were high (> 52%), implying good utilization of feed for tissue synthesis and metabolic activities. On the basis of final mean weight gained, feed conversion ratio and the cost-effectiveness of diets, it suggests that BSF larval meal may partially replace fishmeal at best 50% inclusion level without affecting fish growth, health and carcass quality.