Impact of biopesticide – Azadirachta indica on gills of fresh water catfish Heteropneustes fossilis

An investigation on the effect of the Azadirachta indica on the gills of Heteropneustes fossilis was carried out in the laboratory. Fishes were exposed to sub-lethal concentrations of Azadirachta indica for 24,48,72 and 96 hrs. The LC50 values of Azadirachta indica calculated for Heteropneustes fossilis for 24, 48, 72 and 96 hours are 10.5, 8.5, 7.0 and 6.5 ml/L respectively. The gills were removed for histological examination. The results showed that in normal gills of Heteropneustes fossilis shows Primary gill lamella, secondary gill lamella, Inter lamellar space and epithelial cells were observed but with increase exposure, the damage or separation of secondary gill lamellae, epithelial cell hyperplasia, fusion of secondary gill lamella, swelling of secondary gill lamellae and edema, necrosis, hyperplasia, degeneration of cartilaginous bar was observed.