toxic effects of datura metel aqueous leaf extract on common carp – cyprinu scarpio, based on the histology of gills and intestine

background: to solve the problems caused by using synthetic pesticides in agricultural fields and aquaculture ponds studies are being carried out on the feasibility of using biopesticides or plant extracts, which are less toxic. extensive research is being carried out by researchers globally to manufacture pesticides using plant extracts. the present study evaluated the effect of datura metel plant's aqueous leaf extract on histological changes in gill and intestine of the common carp cyprinus carpio. methods: twenty-four hour lc50 value was determined by standard methods and was calculated as 100 ppm. the fishes were exposed to sublethal concentration (1/10th of 24 h lc 50 value i.e., 10 ppm) for a period of 14 d. after 7 and 14 d, the gill and intestine were dissected out from both the exposed and control groups and were processed and sectioned at 4 µm and stained with h & e stain. the slides were then observed under 40 x magnification. results: the exposed gills showed vacuolation, bending of secondary gill lamellae, and cell masses between the secondary gill lamellae thickened to such an extent that interlamellar spaces were completely occluded. intestines demonstrated narrowing of lumen, vacuolation, inflammation and rupture of epithelium. the pathological changes were more severe after 14 days of exposure in both the tissues. conclusion: aqueous leaf extract of d. metel can be used as an agrochemical. because of its toxicity its usage should be monitored well.