EFEITO DA DENSIDADE DE ESTOCAGEM E A RESPOSTA DE ESTRESSE NO POLICULTIVO DE JUNDIÁ ( Rhamdia quelen ) E CARPA HÚNGARA ( Cyprinus carpio )

The objective of this study was to evaluate performance and the level of circulating cortisol in jundia and common carp juveniles reared in polyculture (75% jundia and 25% carp) at two stocking densities (57 and 143 fish/m3) during the growing phase, in closed system. The juveniles of jundia had 24.39±0.54 g of initial medium weight and the carp 27.73±0.22 g. Animals were fed twice daily with the same diet. At the end of trial no significant differences in the performance parameters of both species were detected, except for the total biomass that was higher in the density of 143 fish/m3. Juvenile common carp showed higher cortisol value at the lower stocking density of 57 fish/m3. With these results, we concluded that the densities do not affect fish performance, but the storage of 143 fish/m3 results in higher production per area and lower levels of plasma cortisol in juvenile common carp.