For pest eradication in agriculture the commonly used organophosphate in Kashmir is Quinalphos (QP). Prolonged usage of QP finally reaches to the aquatic environment, wherein it results in considerable threat to the resident organisms. Therefore, the current endeavour was performed to assess acute toxic effects of quinalphos. Moreover, changes in the behaviour, differential leucocyte count (DLC) and genotoxic effects in common carp (Cyprinus carpio var. communis) were also observed. Weight of the fish taken ranged between 10 2 gms and data of mortality was carried using Finney’s Probit Method. For definitive tests, doses were chosen, based on pre- determined range finding tests, run in triplicates. In static bioassay system after 96 h, LC50 value for common carp was observed 13.35 ppm. The fish elicited clinical signs like excessive mucus secretion, convulsions, scale erosions, hemorrhagic patches and uncoordinated movements, change in body colour and surfacing and gulping onto air-water interface was also noticed at 96 h after exposing them to different sub-lethal concentrations of QP i.e., C1 (1/80th of LC50), C2 (1/40th of LC50) and C3 (1/20th of LC50). The results also revealed significant decrease in various parameters such as Tail Beat Frequency (TBF), Opercular Beat Frequency (OBF), Swimming Velocity (VS), Swimming Activity Index (Ai) and Fin Deformities (Fd) with the increase in time and pesticide concentration. Fish also elicited genotoxic response which was evaluated by calculating the frequency of micronuclei formation in their hematocytes at different intervals of 7, 14 and 21 days of exposure. Moreover, variation in the differential leukocyte count was also observed in fishes exposed to different concentrations of the pesticide.