Effects of salinity on survival and growth of sleeper Odontobutis yaluensisJuveniles

Sleeper Odontobutis yaluensis jveniles with body weight of 0.038±0.005g were directly transferred into a tank(45 cm×31 cm×30 cm) from fresh water into salinity of 9.0~14.0(1.0 increment) to determine lethal concentrations(LC50) of salinity and mean survival time(MST)at a water temperature of 25.0℃~28.0℃.It was found that 12~,24~,48~,72~ or 96 h~LC50 of salinity was 13.56,12.76,10.41,9.92 and 9.74,respectively.MST of 37 min 5 sec was observed in the juveniles that were immediately transferred into a salinity of 28.2.The juveniles with the same size as described above were reared at a salinity of 0,2.0,4.0,6.0 and 8.0 for 60 days after they were gradually acclimated to the expected salinity.The results showed that the fish had very significantly higher specific growth rate at a salinity of 2.0 than at a salinity of 0(p 0.01),no significant difference from the fish at a salinity of 4.0,6.0 and 8.0.The juveniles reared at salinity of 2.0 had high digestive protease and amylase activities,and big cells in gills with high respiratory surface area,indicating that the low salinity stress enhanced fish growth during the first 15 days.