Fenvalerate induced changes in the Ach and associated AchE activity in different tissues of fish Cirrhinus mrigala (Hamilton) under lethal and sub-lethal exposure period.

The disruption of acetylcholinesterase activity in freshwater fish Cirrhinus mrigala (Hamilton) is demonstrated in the present study using acetylcholine chloride as substrate. Fish, C. mrigala on exposure to lethal and sub-lethal concentration of synthetic pyrethroid insecticide, fenvalerate showed inhibition in the activity of the AchE suggesting decrease in the cholinergic transmission and consequent accumulation of Ach in the tissues, namely, gill, muscle, liver and brain. This might have lead to behavioural changes and create widespread disturbance in the normal physiology, ultimately causing the death of the fish. Residue analysis using gas-liquid chromatography technique (GLC) revealed that highest quantity of fenvalerate accumulated in gill followed by liver and muscle under lethal concentration, whereas in sub-lethal concentration muscle accumulated highest concentration followed by gill and liver. The results suggest that in biomonitoring programme, AchE can be a good diagnostic tool for fenvalerate toxicity.