Effect of Stocking Density on the Survival and Growth of Hoplobatrachus occipitalis (Günther, 1858) (Amphibia: Dicroglossidae) of Tadpoles Reared in Ponds from Benin

Abstract

The current study aims to evaluate the effect of density on the survival and growth of Hoplobatrachus occipitalis tadpoles in circular plastic ponds (Diameter: 24 cm; volume: 60 L) for 24 days. Four stocking densities (5, 10, 15 and 20 tadpoles/L), respectively represented by D1, D2, D3, and D4 were tested on tadpoles (initial mean weight 0.283 ± 0.031 g) in triplicate. Tadpoles were daily fed at 6% of biomass every hour from 8 a.m to 6 p.m on Coppens fish feed. At the end of experiment, parameters such as final biomass (9.386 ± 0.240 to 23.750 ± 0.601 g), specific growth rate (1.960 ± 0.326 to 4.220 ± 0.255%/d-1), daily weight gain (0.022 ± 0.021 to 0.735 ± 0.026 g/d), survival rate (30.388 ± 1.734 to 86.333 ± 3.333%) and feed conversion rate (1.436 ± 0.023 to 2.185 ± 0.218) showed the lowest values in the highest stocking densities. The final biomass, specific growth rate, daily weight gain and survival rate recorded in D1 tadpoles were significantly higher (p˂0.05) compared to the other lots. Thus the optimal stocking density is 5 tadpoles/L to ensure a good growth of H. occipitalis tadpoles in circular ponds. Indeed, this density has been chosen in relation to the space required by tadpoles for good zootechnical performances.