Randomly selected 320 fingerling of Labeo rohita were collected from Faheem fish farm, Mattital Road, Multan. Groups of 40 fish each were exposed to subleathal concentration of imidacloprid (120 mg L^-1) under short (2, 4 and 8 days) and long term (16, 32 and 64 days) conditions to access the effect of this most extensively used pesticide on the body composition parameters of economically most important fresh water fish, L. rohita, in Pakistan. Separate control groups were used for each imidacloprid treatment. It was found that most of the studied body composition parameters remained unaffected during short and long term experimental treatments as compared to their respective control groups with the exception of the 64 days treatment where several parameters including body weight ( p = 0.02), dry body weight (p = 0.005), % dry weight (p = 0.001), total water contents ( p = 0.04), total fat (p = 0.03), % fat wet weight (p = 0.001), % fat dry weight (p = 0.003), total organic contents (p = 0.04), % organic content wet weight (p = 0.001), total proteins (P p = 0.005) and % protein wet body weight ( p = 0.001) had significantly lower values in imidacloprid treated fish as compared to control group. Our results indicated that chronic exposure of imidacloprid can adversely affect the nutritional quality of L. rohita.