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. This study assessed the semi-artificial technique of producing catfish larvae with different broodstock ratios using Ovaprim®, a synthetic spawning inducing hormone. The treatments with 3 replicate each 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 brooders in T1, T2, and T3 was 68 ± 6.31, 78 ± 12.29, and 65 ± 8.18, respectively with no significant difference (P ≥ 0.05). Percent fertilization for T1 (81±1.52%), T2 (75 ± 2.51%) and T3 (62 ± 2.50%) was 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 was not statistically different (P ≥ 0.05). Differences in total egg weight (96 ± 3.30, 72 ± 10.53, and 59 ± 0.50 g; p=0.099), and total larval production (57,700 ± 3672; 42,423 ± 6972 and 34,078 ± 762; p=0.002) for T1, T2 and T3, respectively, were statistically significant between artificial spawning and semi-artificial spawning. Larval survival was significant (P ≤ 0.05) between T1 (84 ± 2.31) and T3 (92 ± 2.50) but both did not differ significantly (P ≥ 0.05) from T2 (87 ± 2.51). In conclusion, the semi-artificial spawning of C. gariepinus with Ovaprim® could be beneficial to fish farmers if done at a broodstock sex pairing ratio of 1:1.

Key words: Clarias gariepinus, induced breeding, Ovaprim®, semi-artificial, aquaculture.