Aquaculture Crsp 22nd Annual Technical Report

This experiment was conducted for 150 days in 15 earthen ponds, 100 m2 in surface area and 1.2 m in depth, at the Institute of Agriculture and Animal science (IAAS), Rampur, Chitwan, Nepal. One cage (1.5 x 1.5 x 1 m and water volume of 2-m3) covered with 1-cm mesh net was suspended in each of the treatment ponds. There were one control and four treatments with three replicates each: carps at 1 fish m-2 in open ponds without cages (control); Sahar at 5 fish m-3 in cages and carps at 1 fish m-2 in open ponds (5 fish m-3); (3) Sahar at 25 fish m-3 in cages and carps at 1 fish m-2 in open ponds (25 fish m-3); Sahar at 50 fish m-3 in cages and carps at 1 fish m-2 in open ponds (50 fish m-3); Sahar at 100 fish m-3 in cages and carps at 1 fish m-2 in open ponds (100 fish m-3), giving ratios of caged to open-pond fish of 0:1, 0.1:1, 0.5:1, 1:1, and 2:1. Caged Sahar were fed with a locally made pelleted feed (28% crude protein), while no feed or fertilizer was added into open water of treatment ponds. The control ponds were fertilized weekly using DAP and urea at rates of 4 kg N and 2 kg P ha-1 d-1. Survival of Sahar was high without significant differences among treatments. Daily weight gains of Sahar, ranging from 0.11 to 0.25 g fish-1, were significantly higher at low stocking densities of Sahar. Feed conversion ratio (FCR) of Sahar ranged from 2.2 to 2.8, and was not significantly different among treatments. The total net and gross yields of all carps were significantly higher in the control than in treatments. The total net and gross yields of carps in the control were significantly higher than the combined net and gross yields of Sahar and carps in all treatments. The overall FCRs in the treatments were 0.15–0.95, and were significantly better in the lower Sahar density treatments. The control and all treatments produced positive net returns, and the highest net returns were produced by the control, followed by treatments with high to low stocking density of Sahar. This study demonstrated that high-valued Sahar has potential to be cultured in an integrated cage-cum-pond system, but it is necessary to fine-tune stocking ratios of Sahar to carps. This can be accomplished by adjusting stocking density of Sahar in cages, cage size, or cage number. Growth could also be improved by providing higher quality feed.