THE INFLUENCE OF STOCKING DENSITY ON THE GROWTH, BLOOD BIOCHEMISTRY, AND ANTIOXIDANT CAPACITY INDICATORS OF CHINESE PERCH (SINIPERCA CHUATSI)

The present study was to explore the influence of stocking density on the growth, blood biochemistry, and antioxidant capacity indicators of Chinese perch (Siniperca chuatsi) cultured in the bank (60 cm× 60 cm×40 cm) based recirculating systems for 40d. Fish (average weight 175.76±15.85 g) were reared in triplicate under five densities: extra-low stocking density (ELD; 3.34 kg/m³); low stocking density (LD; 9.51 kg/m³); medium stocking density (MD; 15.82 kg/m³); high stocking density (HD; 21.05 kg/m³) and extra-high stocking density (EHD; 25.99 kg/m³). After 40 days, growth performance, biochemical parameters, appetite-related genes expression and stress indicators of fish were evaluated. The results showed that the ELD and LD groups showed better productive performance for weight gain (WG) and feed conversion ratio (FCR) (P<0.05), and increased plasma superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, and decreased the formation of malondialdehyde (MDA) (P<0.05). Additionally, the EHD group performed higher glucose levels, cholesterol levels and lower triglyceride levels in plasma (P<0.05). The mRNA expression of agouti gene-related protein (agrp) was riesd in LD group, whereas gene expressions of pro-opiomelanocortin (pomc) resulted in a down-regulation in ELD group. In sum, the suitable stocking density for culturing Chinese perch in recirculating systems is recommended to be between 3.34 and 9.51 kg/m³. It is of great significance to select the best stocking density for improving the economic benefit of fish culture.