Culture of the Australian red-claw crayfish (Cherax quadricarinatus) in Israel IV. Crayfish incorporation into intensive Tilapia production units

Abstract

This study tested the suitability of the Australian red-claw crayfish Cherax quadricarinatus for rearing in an intensive culture system as a supplement to Oreochromis niloticus. Fish were grown in twelve 5.5 m3 tanks at high density (33/m3) for 133 days, alone or with crayfish at two stocking densities (10/m2 and 20/m2) with added shelters or with crayfish at the lower density (10/m2) without shelters. Tilapia survival ranged 90.3-95.0% with no significant differences among treatments. The growth rate of the tilapia raised with crayfish (2.05 g/day) was significantly higher than that of tilapia grown alone (1.88 g/day) probably because the fish were feeding on part of the crayfish pellets. Among treatments, there were no significant differences in fish yield. Crayfish survival was extremely low in the 'no shelter' treatment (2.9±2.7%) but reasonable (approximately 60%) when raised with shelters. The growth rate of the crayfish raised with shelters was significantly higher at the lower density (0.21 g/day) than at the higher density (0.18 g/day). Further research is needed on rearing tilapia and crayfish to market size in intensive systems, to establish the economic profitability of this culture strategy.