Crocker et al.1981 reported that values for osmolality were lower for juvenile red drum held in fresh water (298 mmol/kg) than those held in sea water (350 mmol/kg), similar to observations in the present study. Analysis of whole body dry weight from the second trial showed that fish reared in the 30 ppt treatment had significantly (p=0.021) higher whole body dry weight (27.15%) than fish reared in either the 5 (25.42%) or 15 (25.52%) ppt treatments. This increase in dry weight is consistent with increases in serum osmolality and demonstrates that the fish reared in the higher salinity retained less water in the tissues than fish reared either the 5 or 15 ppt treaments.