Malathion toxicity: in vivo inhibition of acetylcholinesterase in the fish Brachydanio rerio (Cyprinidae).

Acetylcholinesterase (AChE) activity in the nervous tissue (brain) of the fish Brachydanio rerio was significantly inhibited by exposure to the organophosphorus (OP) pesticide, malathion. The inhibition was dose- as well as time-dependent. The fish survived even when the activity of the enzyme was inhibited by 90%. There was a significant recovery in the activity of AChE when malathion stress was lifted.