The effects of resin acids on the development of, and recovery from jaundice in rainbow trout were studied. 2. At 0.4 mg/l or higher resin acid concentration, fish developed jaundice in 2-4 days at water temperatures over 17 degrees C and recovered from severe intoxication within 6 days. 3. Jaundice results at least partially from insufficient secretion of conjugated bilirubin into the bile, probably because resin acids and bilirubin share a common secretion pathway. 4. The activity of liver UDP-glucuronosyltransferase and concentration of plasma bilirubin are sensitive indicators of the exposure of trout to discharges containing resin acids.
