Behavioural effect of heavy metals on common carp (Cyprinus carpio L.) and Nile tilapia (Oreochromis niloticus L.)

The study aimed to investigate the effect of two heavy metals of cadmium and lead on the behaviour of two fish species, viz. Cyprinus carpio and Oreochromis niloticus. Two behavioural models, including the mirror-biting test and the dark/light test. The results showed that a significant relationship between the social behaviour of the fish species and the exposure to the selected heavy metals. Fishes exposed to heavy metals showed a significant decrease (P 0.01) in the number of mirror bites in the mirror biting test. Moreover, the results of the dark/light test showed that there was a significant reduction (P 0.01) in the total time spent in by fishes exposed to heavy metals in the light compartment.