During the present research, C. idella and C. auratus fish were exposed to 2 ppm concentration of imidacloprid for 28 and 24 days, respectively, and the effect on biochemical and haematological parameters was investigated. During the study of biochemical parameters, there occurred significant increase (P<0.05) in the serum levels of ALT and creatinine of imidacloprid exposed groups of both species of fish. The level of serum albumin of imidacloprid exposed groups of both fish species was significantly lower as compared to control group (P<0.05). Serum globulin level in imidacloprid exposed group of C. idella was insignificantly lower as compared to control group, however the serum globulin level of C. auratus was significantly lower than the control group (P < 0.05). The level of total proteins in serum of imidacloprid exposed groups of both fish species was insignificantly lower as compared to control groups (P>0.05). During the study of haematological parameters, TLC of C. idella was insignificantly (P>0.05) higher than control group but the TLC of C. auratus was significantly (P<0.05) higher than control. There was also observed increasing trend in the percentage of neutrophils and lymphocytes of imidacloprid exposed group of each fish species. The platelets count of imidacloprid exposed group of each fish species was significantly (P<0.05) lower than control group. The haemoglobin concentration of imidacloprid exposed group of C. idella was significantly lower than control group (P<0.05). In case of C. auratus, the haemoglobin level of imidacloprid exposed group was insignificantly lower than control group (P>0.05). From the finding of the present research it was concluded that 28 days exposure of C. idella and 24 days exposure of C. auratus to 2 ppm concentration of imidacloprid does not cause mortality however the exposure causes alteration in the normal level of biochemical and haematological parameters.