Oxygen Consumption and Hypoxic Tolerance of Triploid Rainbow Trout

Abstract

Triploid rainbow trout were compared with diploid ones in oxygen consumption, hypoxic tolerance, and mortality from bacterial gill disease. Triploids showed almost the same rate of oxygen consumption (ROC) with diploids at environmental dissolved oxygen concentration between 2-6ml/l, but the ROC of the triploids was significantly lower than that of diploids at 1.6ml/l. Triploids also showed a surfacing behavior at higher dissolved oxygen concentrations than diploids. However, there was only a minor, if any, difference in dissolved oxygen concentration at which fish began to lose equilibrium. Triploids which had lost equilibrium needed longer time for recovery.
Triploids showed higher mortalities in water under 50% saturation of dissolved oxygen when infected with bacteral gill disease. It was thought that the poor intake of oxygen due to bacterial gill disease produced more serious hypoxia in triploid rainbow trout.