Tolerance to ethanol: effect of congeners present in bourbon.

Fish were exposed to water and to ethanol or bourbon solutions of the same ethanol concentration (0.1, 0.2, 0.4, 0.6, or 0.8 g/100 ml) during 6 h and then tested in 3.1 g/100 ml ethanol for loss of righting reflex or overturn point. The content of ethanol in the brain at overturn was determined for each fish. Although the ethanol brain levels at overturn of bourbon-exposed fish were higher than those of the ethanol group, no significant differences were observed between the two groups. Moreover, there was a tendency for the bourbon fish to take longer times to overturn than the ethanol fish. These findings indicate that the congeners present in bourbon did not affect significantly the development of tolerance to ethanol in goldfish.