Freshwater fish Channa punctatus was exposed to the synthetic pyrethroid cypermethrin in in vitro conditions. At 5.0 ppm or more concentration cypermethrin caused acute toxicity in this fish within 48 hours. For studying the changes in the levels of organic constituents in this fish, three sublethal concentrations of cypermethrin viz. 0.10, 0.20 and 0.30ppm were selected and fish were exposed for a maximum period of 30 days. The effect of exposure was studied on organic constituents in muscle and liver after 5, 10, 15, 20, 25 and 30 days. Exposure to cypermethrin caused significant changes in protein, total amino acids, glycogen, total fat and cholesterol. The results are discussed to study the effect of in vitro exposure of Channa punctatus to sub lethal concentrations of cypermethrin.