Effect of Ovaprim doses and latency periods on induced spawning of Clarias batrachus: observation on larval deformity.

ABSTRACT

Induced spawning of C. batrachus was conducted at different Ovaprim dose and latency period combinations to observe the deformed larvae among the hatchlings. For the purpose, four doses of Ovaprim (0.5, 1.0, 1.5 and 2.0 ml/kg body weight) and five latency periods (11, 14, 17, 20 and 23 hr) were considered in 20 different combinations. There were no deformed larvae in the females injected with all four doses and stripped at 11 hr latency, as the eggs did not hatch. The percentage of deformed larvae (4-7%) did not vary significantly at 1.0-2.0 ml dose level in combination with 14-17 hr latency periods. While increasing the latency period beyond 17 hr at 1-1.5 ml dose level, the percentage of deformed larvae increased significantly and touched as high as 11%. The results indicated that 1-1.5 ml dose in combination with 14-17 hr latency are suitable to reduce the deformed larvae among the hatchlings during induced spawning of C. batrachus.