水産養殖研究開発ジャーナル

概要

Effects of Catfish (Clarias gariepinus) Brood-stocks Egg Combination on Hatchability and Survival of Fish Larvae

Onada Olawale Ahmed and Ogunola Oluniyi Solomon

Fish seed production of catfish and tilapia has been successfully carried out in Nigeria. Despite the success, there still exist a wide gap between fish seed demand and supply, this therefore necessitate increased research for development. This project is aimed to study the effects of Clarias gariepinus brood-stocks’ egg combination on hatchability and survival of fish larvae.

2 females gravid Clarias gariepinus brood stock size (800-900 g) were injected with pituitary gland hormone at 3 mg kg-1 of body weight. Milt gotten from the selected male was mixed with collected eggs of injected females after the expiration of latency period. 1/3 of the eggs collected from T1 (first female brood stock) and T2 (second female brood stock) were combined and recorded as T3 (mixture of 1/3 of T1 and T2). Each of T1, T2 and T3 were replicated as T11, T12, T13, T21, T22, T23, T31, T32, T33. Each of the replicated fertilized egg was spread in a monolayer pattern on a 1 mm diameter net in nine 0.8 m × 0.8 m × 0.8 m aquarium tank under a recirculatory system. Water quality, fecundity, fertilization rate and survivability of fish were determined. The data collected were analyzed using analysis of variance (ANOVA) at p < 0.05 significant level.

The percentage fertilization was 62.34a, 61.98a and 62.75a for T1, T2 and T3 respectively. The percentage hatchability was 52.11a, 50.32a and 51.51a for T1, T2 and T3 respectively. The survivability result shows relatively high survival rate in treatment T1 and T2, while the rate of survival in T3 was very low.

Egg combination does not have effect on fertilization rate and hatchability of eggs; however, it reduces the survival of larvae. In order to increase survival of catfish fry, it is important to avoid mixture of eggs from multiple brood fish.