The interrelationships between stress and osmoregulation in a euryhaline fish, Oreochromis mossambicus

Three groups of Oreochromis mossambicus, progeny of a single couple, acclimated to freshwater, seawater and iso-osmotic water, respectively, were confined for 4 h following the same experimental procedures. Confinement stress evoked a ‘simple’ stress response that produced a significant rise in cortisol and glucose and slight osmotic disturbances for each tested salinity. It was speculated that the mechanisms securing osmotic homeostasis in this extremely euryhaline species favour it from a wide osmotic stress-evoked disturbance.