Effect of stocking density on survival rate and growth performance of shi drum (Umbrina cirrosa, Lin. 1758)

The effect of different stock density on survival rate, growth performance, cotisol and glucose levels of shi-drum (Umbrina cirrosa) juvenils were investigated in this study. The Shi- drum juveniles, mean initial weights ranging between 30.21±0.27 and 31.06±0.17 g were stocked at densities of 1, 2, 3, 4, 5, 6 and 7 kg /m3 with triplicate. Fish were fed ad libitum for 12 weeks. Final weight, survival rate, weight gain, daily weight gain, daily feeding rate, mean daily growth rate, daily growth rate index and specific growth rate at 1 and 2 kg/m3 were significantly higher than the other densities (P>0.05). Feed efficiency and feed conversion rate at 7 and 6 kg/m3 significantly higher than the other groups (P>0.05).According to the result of blood analyses were undertaken to investigate the effects of stock density on stress; although cortisol levels at 1 and 2 kg/m3 significantly higher than the other density groups. However, it was determined that stocking density had no significant effect on glucose levels of different groups. It was concluded that stocking density was an important growth factor and weight gain and the other growth parameters of lower stock density groups were better than the others. Although feed efficiency and food conversation rates were better than higher stocking density groups, survival rate decreased probably because of stress in the same groups.