Snakeheads were adapted to fresh water (1 mOsm kg-I), 25% sea water (230 mOsm kg-I),
33% sea water (320 mOsm kg-I) and 40% sea water (380 mOsm kg-I) for 20 days. Exposure
to salt water resulted in tissue dehydration, elevations of plasma osmolality, Na+, Mg2+, CIand
protein concentrations and stimulation of branchial Na+-K+-ATPase activity. These
changes were accompanied by concomitant decline of the hepatosomatic index and liver
glycogen concentration. The routine rate of oxygen consumption was increased in snakeheads
adapted to 33% sea water. These data were taken to indicate a stressful effect of
salinity to the snakehead despite documentation of its ability to penetrate into brackish
waters.