INDUCED SPAWNING BY LHRHA AND PIMOZIDE IN THE ASIAN CATFISH CLARIAS-MACROCEPHALUS (GUNTHER)

Experiments were conducted to determine the optimum dose of luteinizin g hormone-releasing hormone analogue (LHRHa) and pimozide (PIM) inject ed simultaneously to yield a high ovulation rate and produce sufficien t eggs in the Asian catfish Clarias macrocephalus. In June 1990, injec tion of 0.05 or 0.10 mug LHRHa/g body weight (BW) + 1 mug PIM/g result ed in 100% ovulation, while only 80% of gravid catfish injected 0.025 mug LHRHa + 1 mug PIM/g ovulated. Most of the eggs stripped from 6 out of 8 control fish were not mature. Fertilization and hatching rates o f LHRHa + PIM-induced fish (75-90% and 39-51%, respectively) were high er than those of control fish (36-39% and 0-1%, respectively). In Augu st and September 1990, all gravid catfish ovulated after injection of 0.05-0.10 mug LHRHa + 1 mug PIM/g BW. However, only 20% of the fish gi ven 0.025 mug LHRHa/g + 1 mug PIM/g BW in August ovulated. No eggs cou ld be stripped from any of the control fish in August and September 19 90. Techniques developed in this study showed a simple and effective w ay of spawning captive catfish, C. macrocephalus. A simultaneous intra muscular injection of 0.05 mug LHRHa + 1 mug PIM/g and stripping of eg gs at 16-20 h post-injection have been tested to yield high ovulation, fertilization and hatching rates.