Conclusion
The current study evidenced that chlorpyrifos is
highly toxic and had a detrimental impact on the
behavioural responses of C. carpio at sublethal
concentrations. It reduced/decreased the animals’
ability to adapt to its environment by 1) increasing the
time required to learn to escape or to avoid external
noxious stimuli, 2) decrease the animal sensitivity to
subtle changes in the environment, or 3) interfere with
the animals’ ability to retain previously learned
behavior. Thus, chlorpyrifos reduced instinctive
behavioural response and affected morphological
features. Impairments in behavioural responses even
under recovery periods may be due to inhibition of
brain AChE activity by chlorpyrifos-oxon via
biotransformation of bioaccumulated chlorpyrifos in
the tissues into their active oxygen analog
(chlorpyrifos-oxon). These behavioural responses can