Effect of different concentration of cypermethrin on various histological structure of intestine of Schizothorax esocinus. (A) Control showing normal structure of intestine, epithelium, serosa and sub mucosa. (B) fish exposed to 1 ppb showing (BC) Blood congestion, (N) Necrosis and (NT) Necrosis of tip. (C) fish exposed to 2 ppb showing (NT) Necrosis of tip, (DC) Destructive changes and (UM) Ulceration of mucosa. (D) fish exposed to 3 ppb showing (BC) Blood congestion, (S) structural integrity loss and (UM) Ulceration of mucosa. (E) fish exposed to 4 ppb showing (UM) Ulceration of mucosa, (P) Pyknosis, (NT) Necrosis of tip and (SM) Shrinkage of mucosa.