Effects of stocking densities of tilapia Oreochromis niloticus (Linnaeus, 1758) with the inclusion of silver carp Hypophthalmichthys molitrix (Valenciennes, 1844) in C/N-CP prawn Macrobrachium rosenbergii (De Man, 1879) culture pond

摘要

The effects of stocking density of tilapia Oreochromis niloticus with the inclusion of silver carp Hypophthalmichthys molitrix were evaluated in the C/N-CP prawn Macrobrachium rosenbergii farming system in triplicate. Management practices were same for all treatments. Bamboo side shoots were posted vertically into the pond bottoms as a periphyton substrate. A locally formulated and prepared feed containing 15.44% crude protein with a C/N ratio 15 were applied twice daily in all ponds. Maize flour was supplied in water for raising the C/N ratio 20 in all treatments. Water quality parameters, except transparency and chlorophyll a, did not differ significantly (P & 0.05) among the treatments. The periphytic abundance and biomass differed significantly (P & 0.05) among the treatments and even among different months. Although the individual harvesting weight, individual weight gain, and SGR were significantly higher (P & 0.05) in the T-10000 treatment compared to T-15000 and T-20000 treatments, respectively, the gross and net yields of tilapia were significantly higher (P & 0.05) in the treatment T-20000 followed by T-15000 and T-10000 treatments resulting in higher combined gross and net yield of both prawn and tilapia (16.05 and 16.92%, 32 and 33.59% from the later two treatments, respectively) with a higher economic return (BCR 0.53) during a 122-day culture period. As a whole, the study revealed that prawn, tilapia, and silver carp with a stocking density at 30,000, 20,000, and 1250 ha(-1), respectively, was found to provide an optimum and sustainable production as well as economic benefit in the C/N-CP-based culture system.