The present study was under taken to assess the Electrophoretic Esterase Enzyme banding pattern alterations in intestine and muscle tissue of fresh water fish Channa punctatus (Bloch) exposed to Malathion( an Organophosphate) at different time intervals i.e. 24H, 48H, 72H and 96H and was compared with control. The esterase isozymes were quantitatively analyzed by using 7.5٪ native polyacrylamide gel electrophoresis (PAGE) stained with α-naphthyl acetate as substrate. Three different esterase Isozyme bands were detected and named as Est-1; Est-2 and Est-3 with different relative mobilities such as 0.6± 0.05; 0.4± 0.05; 0.3± 0.05 in gill, liver and brain tissue. All the three esterase bands were found in intestine and muscle tissues tissues in control. After the fish is exposed to Malathion (an Organophosphate),