Rainbow trout, Oncorhynchus mykiss, reared in water containing oxygen at 180% or 94% of saturation for 125 days showed no difference in growth or feed conversion. Hematocrits were nominally reduced in fish held in the supersaturated oxygen environment, but increased within 35 days of returning the fish to water at 94% oxygen saturation. Mortality was not affected. Hemoglobin levels did not differ statistically between treatments by the end of the trial. Cutthroat trout, O. clarki, reared in 183%, 127% or 97% oxygen-supersaturated water for 91 days also showed no differences in growth or feed conversion. Hematocrits decreased nominally as dissolved oxygen was increased. There were no differences in mortality during handling or distribution stress tests. Results of these trials indicated that long-term culture in water saturated up to 183% oxygen has no adverse effect on growth or survival of these two species. © 1990.
