After three weeks of acclimation, juvenile fish (n = 78; 0.35 ± 0.01 g wet body mass; 4.99 ± 0.14 cm total length; mean ± SD) were gradually acclimated from freshwater (17 mOsm kg− 1; ~ 0.6 salinity, hereafter referred to as 0 to a salinity of 43 (1230 mOsm kg− 1). pumping natural seawater from a reservoir at a flow rate of ~ 300 ml h− 1, into a 70-l plastic tank. The hypersaline treatment was prepared by the addition of commercial marine salt to natural seawater. Aeration was provided throughout. Once each experimental salinity (~ 0, 5, 10, 20, 33 and 43) was reached. fish (n = 11-13) were transferred to a separate 30-l plastic tank where the experimental salinity was held constant. Once all fish had reached their target salinity, fish were held for a further period of seven days. Partial water changes (50%) were performed daily with water at the appropriate salinity.