Effects of sublethal exposure to copper on diel activity of sea catfish, Arius felis

A. felis were exposed to 0, 0.05, 0.1 or 0.2 mg per copper litre for 72 h. Diel behaviour of copper exposed fish (0.05 mg per litre) did not differ from controls. However fish exposed to 0.1 and 0.2 mg copper per litre were hyperactive immediately following exposure as measured by the number of locomotor events per h. The normal diel activity cycle was also abolished. There was significantly less variance in activity for fish exposed to 0.1 and 0.2 mg copper per litre compared to fish in the other 2 treatment groups, further indicating the abolishment of the normal diel activity pattern.