In the current study, the effect of fresh water and different salinities of 15, 35 and 50 ppt on growth, feeding, body composition, glucose and cortisol in Asian sea bass (Lates calcarifer); were investigated. 180 fingerlings with average weight of 34.36±0.41 gram in 12 circular fiberglass tanks with 300 liter volumes were administered. Feedinng was done to satiation twice a day for 30 days. At the end of the experiment, biometry carried out and plasma and carcass samples were collected for estimating blood biochemical parameters and whole body composition. The obtained results showed that freshwater treatment had a significant difference in growth and feeding performance with other treatments (p < 0.05). Also, the results of carcass analyze showed that freshwater treatment moisture percentage was significantly higher (72.07±0.11) compared to other treatments (p < 0.05). Glucose and cortisol value in 15 ppt treatment were significantly higher at 35, 50 ppt treatment and 35 ppt, freshwater treatment, respectively (p < 0.05). Overall, this study showed this species is able to tolerate changes in salinity in the surrounding medium from seawater to brackish water through a period of 30 days and successfully adapt to freshwater without showing mortality. But, it could not be a good case for culture in fresh water because of using high energy for osmoregulation in fresh water.