Abstract: The exposure to fish over 96 h to sub-lethal doses 8.24 mg, DW L-1 and 16.48 mg, DW L -1 of stem-bark extracts of Croton tiglium of family Euphorbiaceae significantly altered the level of total protein, total free amino acids, nucleic acids, pyruvate, lactate, glycogen and activity of succinic dehydrogenase, lactic dehydrogenase, cytochrome oxidase, acetylcholinesterase, acid and alkaline phosphatase and protease activity in muscle, liver and gonadal tissue of fish Channa punctatus. The alteration in all the biochemical parameter was significantly dose dependent. Withdrawal study also shows that there is a partial recovery in the levels of glycogen, pyruvate, nucleic acids, acetylcholinesterase, cytochrome oxidase and acid and alkaline phosphatase, but nearly complete recovery in total protein, total free amino acids level and activity of protease, lactic dehydrogenase, succinic dehydrogenase and lactate in all the three tissues of the fish after the 7th day of the withdrawal of treatment, which supports the view that the plant product is safer in use as pesticides for control of common weed fishes in culture ponds.