A Preliminary Study on Nile Tilapia (Oreochromis niloticus) Polyculture with Common Carp (Cyprinus carpio) Fed with Duckweed (Spirodela) in Nepal

Abstract

Mixed-sex Nile tilapia (Oreochromis niloticus) and common carp (Cyprinus carpio) were cultured in four cement ponds of 72 m2 at 1:1 ratio with a stocking density of 1 fish· m·2 during summer in subtropical Nepal. Fish were fed with locally collected duckweed (Spirodela sp.) during 108 days of experimental period. Nile tilapia grew from 39.6±3.7 g at stocking to 145±5.2 g at harvesting with a survival rate of 90±4 %. Common carp grew from an initial 2.8±0.G g to final 63.2±2.4 g with 97±1 % survival rate. The ex­trapolated annual yield of stocked fish ranger.! from 2.3 - 2.9 t•ha·1 with a mean of 2.5 ±0.1 t·ha·1. Tilapia offsprings produced during the experimental period was 1690:±261 fish per pond with an average size of 7.2±1.6 g. Weight of tilapia recruits obtained was two times more than that of the net yield of originally stocked fish. The common carp did not control tilapia recruitments.