水産養殖研究開発ジャーナル

概要

Development of Brood-stock Diets for Nile tilapia Under Hapa-in-Pond Hatchery System; Optimal Dietary Vitamin C Level for the Optimum Reproductive Performance and Fry Survival

Ashraf Suloma, Al-Azab M Tahoun and Rania S Mabrok

The hapa-in-pond system is a hatchery technique, which, has been widely developed. In spite, of the research efforts in this field, little information is available considering the nutritional requirement of tilapia brood-stock under hapa-in-pond system hatchery technique and the effects on brood-stock reproductive performance and fry survival percentage. By taking in concern the previous points, five levels of vitamin C (0 mg/kg, 200 mg/kg, 400 mg/kg, 800 mg/kg and 1200 mg/kg) were examined for its effect on reproductive performance of tilapia brood-stock and fry survival under the hapa-in-pond system conditions. Adult males and females with mean body weights of 198 g and 206 g, respectively, with a male to female sex ratio of 1:2. Tilapia breeders were stocked at density 3 fish/ m3; 6 (2♂:4♀/hapa). Tilapia brood-stock fed diet supplemented with Vitamin C (400 mg/kg) showed the highest reproductive performance results (total seed production; 8034 seeds; absolute fecundity of 2008.5 seeds female-1, relative fecundity; 7.57 seeds g female-1, and system productivity of 38.26 seeds day-1 m-2). While the lowest reproductive performance and fry survival percentage recorded for diet without Vitamin C supplementation. Fry survival results showed no significant among different diets supplemented with Vitamin C, while the control recorded the lowest (P<0.05) fry survival percentage. It could be concluded that, the optimal vitamin C level for brood-stocks under conditions of hapa-in-pond hatchery system is 400 mg/kg.