Advanced nursing of Clarias gariepinus (Burchell, 1822) fingerlings in earthen ponds, through recycling of tilapia recruits

In an attempt to improve the stocking size and yield of Clarias gariepinus, small fingerlings (average weight = 3 g) of the type usually produced by African hatcheries were stocked together with tilapia (Oreochromis niloticus) broodfish at a ratio of 1 g of fingerlings to 3.64 ± 0.39 g of broodfish. Holding ponds were so prepared that persisting leaks did not cause water level drops of more than 2 cm/night and water temperature, pH and transparency respectively averaged 27.3°, 6.5 and 20.8 cm. Results showed that C. gariepinus fingerlings stocked with tilapia broodfish preyed on tilapia recruits and thus grew faster, survived better and withstood higher stocking densities than those in ponds without tilapia. Availability of tilapia recruits significantly enhanced C. gariepinus fingerling survival (P < 0.05), final average weight (P < 0.03) and number harvested/m2/56 days (P < 0.003). It also permitted an increase of stocking density from 3 to 4 fingerlings/m2 with no significant decline in tested parameters.