Reduced territorial defence in rainbow trout fry exposed to a paper mill effluent: using the mirror image stimulation test as a behavioural bioassay

Rainbow trout Oncorhynchus mykiss fry exposed to a paper mill effluent showed increased EROD (ethoxyresorufin-O-deethylase) activity and reduced territorial aggression in mirror image stimulation (MIS) tests. These results suggest that the MIS test could be a useful tool to detect sublethal behavioural effects of pollution in fish fry.