POLYCULTURE OF NILE TILAPIA (OREOCHROMIS-NILOTICUS) AND AUSTRALIAN RED CLAW CRAYFISH (CHERAX-QUADRICARINATUS) IN EARTHEN PONDS

Nile tilapia (Oreochromis niloticus) and Australian red claw crayfish (Cherax quadricarinatus) were cultured alone and together in replicate 0.02 ha earthen ponds to assess the nature and intensity of species i nteraction in polyculture. Treatments were: (I) 10000 tilapia per hect are, (II) 10000 tilapia plus 25000 crayfish per hectare and (III) 2500 0 crayfish per hectare. All ponds were fed a 32% crude protein, pellet ed catfish feed at monthly-adjusted rates based on stocked tilapia bio mass. After 100 days of polyculture, ponds were harvested. Tilapia gro wth, reproduction and food conversion were adversely affected by the p resence of crayfish (P<0.01). Crayfish growth, incidence of intersexua lity and percentage of berried females were not affected by the presen ce of tilapia (P<0.01).