Chlorpyrifos (CPF) is a widely used organophosphate pesticide which has an unfavorable impact on the aquatic ecosystem. This work was designed to compute the LC50 and lethal concentration (96-hr) of chlorpyrifos for Labeo rohita. The LC50 and lethal concentration (96-hr) of chlorpyrifos for Labeo rohita was determined as 10.39±0.03 and 15.31±0.05 μgL-1, respectively. During acute toxicity test, behavioral changes in Labeo rohita were also observed i.e. rapid opercular movement, profuse mucus secretions, imbalance swimming, increased surface activity, loss of equilibrium, convulsion, body discoloration, and decreased hyperactivity. Jumping of fish out of exposed medium proved the avoidance behavior against pesticide toxicity.