Three‐dimensional study on the effect of organophosphate pesticide ‘monocrotophos’ on lens of fish and its recovery

Abstract

The present studies are based on the feedback provided by fish farmers practicing composite fish culture of carps. According to them, fish habitats are affected by pesticides draining from agricultural fields into their catchments, especially during the rainy season. The lenses of most of the cultured fish became opaque, resulting in poor overall growth. In the literature, there was mounting evidence of pesticide toxicity involving multiple tissues. However, the fish visual system has never been investigated particularly from the toxicological perspective. In this regard, we carried out comparative toxicological studies on the lens of Cyprinus carpio communis using three different sublethal concentrations (0.038, 0.062 and 0.126 p.p.m.) of monocrotophos along with untreated controls for 30 days. Lenses from all the groups were extracted and preserved in gluteraldehyde and osmium tetraoxide and dehydrated in increasing grades of acetone. After dehydration, tissues were conducted with gold to observe under SEM. The fish exposed to monocrotophos developed cataract. Furthermore, when fish from the monocrotophos-treated tanks were transferred to normal environmental conditions for the next 60 days, progressive lens degeneration was noted. To conclude, monocrotophos induces irreversible cataractous changes in the lens of C. carpio communis. The fish visual system has many similarities to mammals and may serve as a good model for comparative toxicologic and ophthalmologic studies.