Abstract: The freshwater fish, Cyprinus carpio, exposed to acute exposure period (Lethal concentration for 96 hours = 4.369 ppm) and ½ and 1/4th sub lethal concentrations (2.185 and 1.092 ppm) of chemathoate for 30 days. The protein content various tissues of fish was observed after exposure period. Acute exposure caused a significant decrease the protein content in testis, ovary and brain and insignificant decrease in intestine, muscles, liver and gills, whereas increased protein level was observed in kidney. The two sub lethal concentrations are caused to decrease of protein content in ovary, brain, intestine, muscles, gills and liver for over 30 days exposure period, whereas protein level in testis of fish was increased to 1/4th concentration of LC50 and decrease of protein content was noticed at ½ LC50 concentration of chemathoate.