INDUCED BREEDING OF 2 CLARIID CATFISHES CLARIAS-GARIEPINUS AND HETEROBRANCHUS-BIDORSALIS USING TILAPIA PITUITARY EXTRACTS

Induced breeding trials of two clariid catfishes, Clarias gariepinus a nd Heterobranchus bidorsalis, were conducted using five doses (2, 4, 6 , 8 or 10 mg/kg) of acetone-dried tilapia pituitary (ADTP) extracts. O ocyte maturation and ovulation were induced in female catfishes by sin gle intramuscular injection of 6-10 mg/kg ADTP; optimum results were o btained with 8 mg/kg in both catfishes. At ambient temperature (27 +/- 1 C), ovulation occurred within 14-18 h post-injection resulting in 1 6-20% increase in egg diameter. Fertilization and hatching percentages increased (P < 0.05) with increases in hormone dosage. Survival of fr y fed a mixed zooplankton diet was high (ranging from 79% to 85%) afte r 30 d of rearing.