Determination of optimum latency period for Clarias gariepinus in the arid zone of Nigeria.

Abstract

Varying latency times, 6 hours – 16 hours (time between hormone injection and stripping) were investigated on Clarias gariepinus in the Arid Zone to determine the optimum effective latency time when the highest number of ovulated eggs were viable and thus fertilizable.

      Breeders were collected from the broodstock tank of (5 x 10 x 1.8m) with a drag net and weighed individually.  They were injected intramuscularly, just beside the dorsal fin with OVAPRIM at 0.5ml per kilogram of fish.  At the expiration of the latency period, the female was carefully removed and hand stripped while the male was cut open to remove the testes for external fertilization and incubation.

      The percentage egg fertilization at 9 hours latency time which was high suggest that 9 hours was the optimum latency time for the stripping of Clarias gariepinus eggs after hormone injection in the Arid Zone.  That was the time when most of the eggs in the ovary had ovulated and were therefore fertilizable.