The main objective of this experiment was to see the behaviour, catalase (CAT) activity and total protein contents (TPC) in Ctenopharyngodon idella under binary mixtures of insecticides viz. endosulfan(ES)+chlorpyrifos(CPF) and endosulfan(ES)+bifenthrin (BIF). The fish behaviour was observed from both treated and control groups. Fish under exposure of insecticides mixtures exhibit abnormal behaviour and tried to jump out from water, come to surface and gulp air, showed increased opercular movement and erratic movements, hyper-activity and swimming very fast. Various tissues such as hepatic, neural, renal, cardiac, gills and muscle tissues were studied for the determination of CAT activity and TPC after exposure of 24 and 96 h. Results showed that both treatments caused a significant (P<0.01) decline in CAT activity and TPC of C. idella as compared to control group. CAT activity and TPC decreased with the passage of time. Among both treatments, ES+CPF caused greater decline in CAT activity and TPC. It was concluded that insecticides in mixture form are toxic to fish and response of biomarkers depends on the type of toxicants and exposure duration.