AbstractRespiratory responses of juvenile rainbow trout,Salmo gairdneriRichardson, were determined after approximately 26 h of exposure to dechlorinated tap water (at pH 6.0) containing 50, 100, 200 or 500 μg/L of added aluminum. Aluminum exposure produced significant increases in both opercular rate and cough frequency. Changes in the cough rates were proportional to the aluminum level, and the threshold concentration was approximately 100 μg/L. In addition, spontaneous locomotor activity was reduced by aluminum exposur