Effect of Latency Period on Spawning and Different Salinity Levels on Fertilization and Hatching of Clarias gariepinus and Heterobranchus bidorsalis

Abstract

Mudfish (Clarias gariepinus and Heterobranchchus bidorsalis) broodstock were induced for maturation and ovulatin with acetone –dried carp pituitary (ADCP) at 4mg/kg weight of fish. Different spawning latency periods (SLPs,) for egg stripped per fish were between 8-13 hours with peak at 10 hours. At this SLPs, fecundity was between 33.1 (C. gariepinus) and 29.4 x 10 3 (H. bidorslis) eggs /female brookstock. Fecundity peak of 59.6in C. gariepinus and 51.2 x 10 3 in H. bidorsalis female broodstock occurred at 10 hours. The effect of five (0.0, 0.2, 0.4, 0.6, and 0.8%) different levels of saline solutions on the fertilization and hatching of these mudfish were also investigated. Both fish eggs survived under this range of saline concentration, with survival increasing with an increase in salinity from 0.0 to 0.4% (peak) and decreasing as the level of salinity increase. Analysis of variance (ANOVA) at P > 0.05 between the fertility and hatching at 0.4 and 0.5% salinity was significantly different.