Effect of stocking density on growth and immunity of Scophthalmus maximus reared in recirulating system

Juvenile turbot(Scophthalmus maximus) were stocked and reared at four experiment densities for the study on the effect of stocking density on growth,feed coefficient and immunity.The initial densities were 0.66,1.26,2.56 and 4.00 kg/m2,respectively.The experiment lasted for 75 days with final stocking densities reached 4.67,7.25,14.16,17.77 kg/m2 respectively.It was found that,under the same experiment conditions,higher stocking densities have a negative effect on fish growth.The SGR(special growth rate) for the four treatments were 2.67,2.33,2.29 and 1.98,respectively.The uniformity of weight distributing within experiment groups decreased with increased density.However,the stocking density had positive effect on feed coefficient rate.Treatment 1 had the lowest feed coefficient rate of 0.70 and the highest coefficient was 0.76,found in treatment 4,the treatment with the highest density.It was also found that the stocking density had insignificant impact on liver organ index.This experiment will provide reference for land-based recirculation systems for fish culture.