Induced ovulation and spawning of pond raised African giant catfish, Heterobranchus bidorsalis by exogenous hormones

Artificial spawning was induced in female African giant catfish, Heterobranchus bidorsalis by single intramuscular hormone injections of carp pituitary suspensions (CPS) at 4 mg/kg body weight (bw), 1.5 ml of homoplastic pituitary suspension (HPS) per fish or human chorionic gonadotropin (HCG) at 2000 IU/kg bw, over 3 months of rainy season (June to August) in Nigeria. At ambient temperature (27±1 °C), ovulation occurred within 14–18 h post injection. Egg hydration gave 16–20% increase in egg diameter. Hatching rates were high (>84%) and similar for all hormone-treated fish ( P>0.05). The percentage normal larvae hatched ranged from 81.6% to 86%. They were reared in 500-l circular tanks and fed initially on zooplankton, followed by brine shrimp nauplii and finally weaned onto commercial fish fry diet. During the larval rearing trials for 30 days, survival rates >82% were achieved. Although the four hormones tested were effective inducers, the use of HPS would save operational costs in fish hatchery management in African countries.