Effects of feeding moist and dry diets to redclaw crayfish Cherax quadricarinatus, in tanks

Two experiments were conducted on redclaw crayfish, Cherax quadricarinatus, to test the effect of moist and dry diets on growth, survival and nutritional condition. In the first experiment animals were cultured in 60 L tanks with a flow-through water supply for 84 days at a density of 32 animals m-2 (8 per tank), and were fed one of four experimental diets. Two commercially available diets, a supplemental redclaw pellet and a salmonid crumble diet, were presented as either dry pellets or moist cubes. Animals were fed an equal quantity of dry matter, twice per day. There was no significant difference in survival or growth between any treatments at any time, although there was a slight trend towards better growth by animals fed the moist diets. In the second experiment animals were cultured in 100 L tanks in a recirculating water system for 50 days at a density of 35 animals m-2 (10 per tank). The commercial redclaw diet and a specifically formulated diet, both presented in moist and dry forms, were evaluated. At the completion of the trial, animals were dissected to determine hepatosomatic indices and tail muscle content. Survival and growth was not influenced by diet moisture. The formulated diet resulted in significantly better crayfish growth at day 25, but by the end of the trial there was no significant difference in growth or survival. The crayfish receiving the commercial redclaw diet had higher hepatosomatic indices