Light micrographs of H & E stained sections of Gills of Cirrhinus mrigala: (G1) Control group gills showing normal structure, (G2 to G6) treated groups gills showing various histopathological alterations including fusion of secondary gill lamellae (F), epithelial uplifting of secondary gill lamellae (E) hyperplasia of gill epithelium (H), curling of secondary gill lamellae (C), telangiectasia (T), shortening of secondary gill lamellae (S), disruption of cartilaginous core (DC), lamellar disorganization (LD) and lamellar atrophy (A).