Effect of stocking densities on the growth performance, cannibalism and survival of Asian seabass Lates calcarifer (Bloch, 1790) fry in different nursery rearing system

The effect of stocking density on the growth performance, cannibalism and survival of Asian seabass Lates calcarifer fry in the static water system (SWS), and recirculating aquaculture system (RAS) was investigated. Three stocking densities 0.03, 0.04 and 0.05 ind/L were used, where the initial length and weight of the fry were 2.5 +/- 0.0 cm and 0.27 +/- 0.0 g respectively. At the end of the trial, no significant effect of stocking density was observed on the growth performance of Asian seabass fry (p > 0.05). After 45 days, the total body length and wet body weight were 11.63 +/- 0.18cm and 20.06 +/- 0.98 g respectively obtained from the RAS were significantly higher than the SWS (p < 0.001). The maximum weight gain (WG) and specific growth rate (SGR) were 19.79 +/- 0.98 g and 9.56 +/- 0.10% day(-1) respectively were found in the RAS significantly higher than the results obtained in the SWS (p < 0.001). A considerably lower FCR (0.67 +/- 0.03) in RAS indicated better feed utilization by fish than SWS (p < 0.01). In the present study, cannibalism was highly influenced by the stocking density and culture system and positively correlated with the stocking density. Lower cannibalism was observed at 0.03 ind/L stocking density (27.78 +/- 5.56%), and the cannibalism was (35.97 +/- 6.28%) in the RAS. There was no natural mortality occurred during the experimental period. The present study suggests that Asian seabass fry reared in the RAS with a lower stocking density can significantly reduce cannibalism and increase the survival rate with better growth performance.