Abstract: Breeding density is one of the most important variables in aquaculture, because it directly affects the survival, growth, behavior, health, feeding, and productivity of aquatics and the water quality. Breeding at high density can cause the deterioration of water quality, overcrowding of aquatics, and adverse colony effect. Silver pomfret (Pampus argenteus) is a new candidate species for aquaculture. Until now, few studies have been conducted on the breeding biology of P. argenteus. The aim of this study was to evaluate the effects of breeding density on the growth of juvenile P. argenteus (5.33±0.07 g), and the glycogen and lactate contents as well as the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX) activities in the liver and muscle of the juveniles. The juveniles were kept at the breeding densities of 5, 10, 15, and 25 individuals·m^-3(named D₁, D₂, D₃ and D₄, respectively) for 60 days. At the density up to D₃, the growth rate of the juveniles increased; whereas at D₄, the growth rate decreased. No significant difference was found in the hepatopancreas index and survival rate among the treatments. The glycogen content in the liver and muscle of the juveniles was negatively correlated with breeding density, being the lowest at D₄, while the lactate content in the muscle had no significant correlation with the breeding density. At the densities from D₁ to D₃, the activities of SOD and CAT in the liver and muscle had less change; but at D₄, the SOD activity in the liver and muscle was significantly lower than that at D₂ and D₃, and the CAT activity in the liver was significantly lower than that at D₃. No significant differences in the activities of muscle CAT and liver-and muscle GSH-PX were observed among all treatments. In general, the test breeding densities were not very stressful to the juvenile P. argenteus during the whole experimental period.

Key words: Canopy gap, Edge of canopy gap, Thermal effect, Water vapor effect, Temporal spatial distribution