Popularisation of amphibian tadpoles in nursing African catfish (Clarias gariepinus) fingerlings in hapas

Abstract

In order to enhance the resistance of Clarias gariepinus fingerlings to the multiple predators of lakes and floodplains, we tested the hypothesis that tadpoles were cheap food supplements for the small-size fingerlings usually produced by hatcheries. Six batches of fingerlings (average weight =10.35 g) were stocked in six hapas and supplied with feed pellets for 56 days. Three of the six batches (experimental triplicate) were additionally supplied with tadpoles caught from surrounding nursery ponds while the other three (control triplicate) received none. Comparison of treatments showed that, consumption of tadpoles conferred significantly higher survivals (P < 0.05), number harvested / m2 (P < 0.05) and final average weights (P < 0.02), which were respectively 9.77, 9.02 and 31.96% higher. Therefore, use of tadpoles for catfish feeding could be a low-cost strategy to increase the availability of advanced fingerlings (> 50g) for growing out, even through re-stocking the many over-exploited lakes and flood plains of Africa.

Key words: Fingerlings, catfish, tadpoles, Clarias, re-stocking