Effect of salinity on molting, survival, growth and feed conversion rate of juvenile Penaeus monodon

Juveniles Penaeus mondon with average weight (1.20±0.05 g) were cultured at salinities of 5, 10, 15, 20, 25, 30 and 35. The intermolt period, survival rate, specific growth rate (SGR) and feed conversion rate (FCR) were analyzed. The results showed that survival rate of P.monodon at salinity 5 was the lowest(< 60%) and significantly different (P < 0.05) from that of the other salinity groups, and there were no significant (P>0.05) differences in survival rate among the other salinity groups. With the salinity increasing from 5 to 25, the intermolt period increased, and when the salinity was over 30, the intermolt period decreased, the peak was appeared at salinity 25; there were significant differences among salinity 5, 10, 15 groups, but no significant differences among salinity 20, 25, 30, 35 groups. As the salinity increasing, the SGR and FCR showed a wavy line with double peaks. SGR was higher at salinity 20(3.18±0.14)% · d^-1 and 25(2.98±0.26)% · d^-1. There was a significant positive relationship between the intermolt period and SGR (P < 0.001).FCR was higher at salinity 20~30 and significantly different from that of the other treatments. The results suggusted that the optimal salinity for P.monodon culture was 20~30 at which higher survival rate, SGR and FCR can be attained.