Production of Pacific white shrimp under different stocking density in a zero-water exchange biofloc system: Effects on water quality, zootechnical performance, and body composition

This experiment was conducted to compare water quality, growth performance, body composition, and insulin growth factor gene expression of Pacific white shrimp, Litopenaeus vannamei , reared under different stocking densities (100, 200, 300, and 400 shrimp m- 3) in a biofloc system with zero-water exchange for nine weeks. The results demonstrated that all the water quality variables remained within the acceptable range that are presumed to be safe levels for Pacific white shrimp farming. The weight gain ratio and specific growth rate of shrimp reduced by increasing the stocking density to the lowest values of 2800.00 +/- 105.32 % and 5.34 +/- 0.11 % d-1 , respectively, in shrimp reared under the highest stocking density (400 shrimp m- 3). The highest feed conversion ratio was also obtained under the highest stocking density of shrimp (P < 0.05). A significant decreasing trend of the insulin growth factor-1 gene expression was observed by increasing the shrimp stocking density (P < 0.05). The final yield of shrimp in the present study significantly increased by increasing the shrimp stocking density and reached the maximum value of 3.05 +/- 0.21 kg m- 3 at the highest stocking density. There was no significant difference in the carcass composition of the shrimp among the experimental treatments (P < 0.05), except for lipid content which was significantly higher in shrimp reared under the lowest stocking density (100 shrimp m-3) (P < 0.05). Findings of the current study confirmed a clear effect of stocking density on growth perfor-mance of the Pacific white shrimp with the recommended density of 400 shrimps m- 3 to achieve the maximum yield, while the stocking density of 100 shrimps m- 3 is feasible to reach the highest weight gain and probability of Pacific white shrimp cultured in a biofloc system with zero-water exchange for the present experimental condition, genetics used and nutrition supplementation.