Intensive culture of walking catfish (Clarias macrocephalus) in an outdoor recirculating system integrated with tilapia

Two experiments were conducted with walking catfish (Clarias macrocephalus) at stocking densities of 50, 100 and 150 fish/cubic meter in an out door concrete recirculation system linked to tilapia ponds with a stocking density of 2 fish/cubic meter. Clarias were fed ad libitum with a low cost feed and nutrients from the waste water of Clarias culture was the only input into tilapia ponds. Growth, food conversion, survivals and related water chemistry was evaluated during the two experiments. Fish with mean initial weights of 1.14+-0.02, 1.24+-0.02 and 1.22+-0.01 (g) in treatments with 50, 100 and 150 fish/cubic meter in Experiment 1 reached mean final weights of 7.69+-0.17, 5.11+-0.51 and 6.74+-0.89 (g), respectively in 30 days culture period. The corresponding food conversion ratios and survivals were 1.14+-0.02, 2.69+-0.37, 2.97+-1.08 and 97.8+-0.7, 30.8+-4.5, 36.2+-10.4 (%), respectively. In experiment 2 a similar trend of better growth, conversion and survivals was observed for fish at a density of 50/cubic meter. Fish with mean inital weights of 0.83+-0.01, 0.78+-0.01 and 0.82+-0.01 (g) in treatments with 50, 100 and 150 /cubic meter attained mean final weights of 12.10+-0.17, 9.58+-0.51 and 7.91+-0.89 (g), respectively in 56 days culture period. The corresponding food conversion and survivals were 1.30+-0.03, 1.62+-0.10, 1.94+-0.14 and 97.3+-2.2, 83.6+-4.1 and 82.3+-8.7 (%), respectively. In both experiments, walking catfish in density of 50 fish/cubic meter showed excellent growth, food conversion and survivals. A mean initial biomass of 6.04 (kg) tilapia in the three ponds attained a final biomass of 14.25, 12.8 and 11.8 (kg), respectively utilizing the wastes from the Clarias culture. Tilapia receiving wastes from Clarias tanks with 150 fish/cubic meter attained high mean final weight. Total phosphorous and total nitrogen present in the waste waters of Clarias culture had fertilization effect on the earthen ponds. Loading rate of total phosphorus and total nitrogen into earthen ponds in Experiment 1 and 2 was in the range of 0.002-0.003 and 0.023-0.037 g/day/cubic meter, respectively