Histopathological Alteration induced in gills of juvenile Nile Tilapia Oreochromis niloticus upon exposure to two Bio-pesticides

Abstract

The effects of Neem and Argel leaf aqueous extracts on the histopathology of gills of the fresh water Oreochromis niloticus were investigated. The LC50 after 96 h of exposure to the aqueous extracts of Argel, Solenostemma argel, and Neem, Azadirachta indica, were 0.33 g/L and 0.15 g/L, respectively. Histopathological changes of gills were recorded when juveniles of O. niloticus were exposed to 20 % of 96 hrs LC50 of each aqueous extract for six weeks. Fish gills exposed to a sublethal dose of 0.07g/l. Argel showed bending of secondary lamellae, telangectiasis, cellular hyperplasia of primary filament, shortening of secondary lamellae, pyknosis, and necrosis of secondary lamellae. Gills in fish exposed to 0.03g/l Neem aqueous extract, recorded epithelial lifting of secondary lamellae, cellular hyperplasia of primary filament, necrosis of secondary lamellae, globular haematomas and shortening of secondary lamellae. The level of severity of lesions increased with incease in exposure time. Therefore the present study concluded that the aqueous extracts of, Solenostemma argel and Azadirachta indica should be used with precaution in the agricultural fields. Nevertheless these two plants can be recommended as an environmentally sound alternative for synthetic piscicides