Abstract:
Modern methods of producing African catfish (Clarias gariepinus) fingerlings require that the male brooder is sacrificed to obtain milt for artificial fertilization of the eggs stripped from the female under hormonal induction. The objective of this research was to study the semi artificial technique of producing catfish larvae with different brood stock ratios using Ovaprim. The experiment was made up of three (3) treatment groups and each treatment had three (3) replicates each. The treatments were T1 (artificial spawning with 1:1 female: male ratio), T2 (semi artificial spawning with 1:1 female: male ratio) and T3 (semi artificial spawning with 2:1 female: male ratio). The relative fecundity of female brooders in T1, T2 and T3 were 68 ± 6.31, 78 ± 12.29 and 65 ± 8.18 respectively and they were not significantly different (p>0.05). Percentage fertilization for T1 (81±1.52%), T2 (75 ± 2.51%) and T3 (62 ± 2.50%) were significantly different (p<0.05). The observed percent hatchability (85 ± 2.51%, 83 ± 3.21% and 82 ± 2.50%) in respect of T1, T2 and T3 were not statistically different. Differences in total egg weight (96 ± 3.30 g, 72 ± 10.53 g and 59 ± 0.50 g), and total larval production (57,700 ± 3672; 42,423 ± 6972 and 34,078 ± 762) for T1, T2 and T3 respectively were statistically significant (p<0.05) between artificial spawning and semi artificial spawning. Larval survival was statistically (p<0.05) different between T1 (84 ± 2.31) and T3 (92 ± 2.50) but both did not differ significantly from T2 (87 ± 2.51). In conclusion, semi artificial spawning of C. gariepinus with Ovaprim could be beneficial to fish farmers if done at a brood stock sex pairing ratio of 1:1.
