Although it is depended to fish species, cortisol secretion and elevation of circulatory glucose are early common responses. The activity of Na/K ATPase will increase in the gills. Gills respond morphologically by hypertrophy and hyperplasia and increased chloride cell size and perhaps number. Because of elevated demand for energy to combat salt stress, any other pathways relating to energy metabolism may be affected (e.g. thyroid function, insulin, gluconeogenesis, glycolysis and ...).