Spawning performance and egg quality of Asian catfish Clarias batrachus (Linn.) at various doses of human chorionic gonadotropin (HCG) injection and latency periods during spawning induction

Attempts were made to spawn Clarias batrachus by injecting human chorionic gonadotropin (HCG) at different doses (1000, 2000, 3000, 4000 and 5000 IU/kg body weight) in combination with latency periods (11,14, 17, 20 and 23 h). The females could not be stripped at 11 h latency when injected with 1000–3000 IU of HCG per kg body weight. A significant (P < 0.05) reduction of stripped egg number was observed when females were injected with a dose of 5000 IU HCG and stripped at 20–23 h post-injection. The eggs obtained from the females with injection of 4000–5000 IU per kg body weight and stripped at 11 h post-injection, did not fertilize. The highest fertilization (75–89%) and hatching (66–78%) could be obtained at 3000–5000 IU doses of HCG with 14–17 h post-injection. Although the highest working fecundity was obtained with 4000 IU HCG at 14 and 17 h latency, the response from 3000 IU HCG was only slightly less at these latency periods, and was effective for up to 23 h.