A preliminary study on Nile tilapia (Oreochromis niloticus) polycuture with common carp (Cyprinus carpio) fed with duckweed (Spirodela) in Nepal

摘要

Mixed-sex Nile tilapia (Oreochromis niloticus) and common carp (Cyprinus carpio) were cultured in four cement ponds of 72 m~2 at 1:1 ratio with a stocking density of 1 fish centre dot 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+0.6 g to final 63.2 +- 2.4 g with 97 +- 1% survival rate. The extrapolated annual yield of stocked fish ranged from 2.3 - 2.9 t centre dot ha~(-1) with a mean of 2.5 +- 0.1 t centre dot 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.