Ivermection is widely being use for treatment of ectoprarastic infestation in fishes globally in carp farming. The post treatment mortality of the fish or subsequent slow growth becomes common due to unregulated dose. Therefore, present study was aimed to study the effect of acute sub- lethal ivermectin administration (96 hr) on antioxidative enzymes (catalase, superoxide dismutase, glutathione S-transferase) and hematological parameters like platelets, white blood cell (WBC), red blood cell (RBC), haemoglobin content, blood glucose and Nitro-blue tetrazolium (NBT) of a tropical freshwater fish, rohu  (Labeo rohita). The calculated LD50 value was found to be 1.81 mg/Kg at 96 h by probit analysis. The three sub lethal doses like 125 125 µg/Kg, 250 µg/Kg , 500 µg/Kg and one control (0.00 µg/Kg ) were intraperitoneally administered. After 96 hours it showed significantly altered (P < 0.05) activities of anti-oxidative enzymes and hematological profile, in a dose dependent manner. The early gross sign like sluggishness and dark body were recorded during acute toxicity study. The result indicates ivermectin can impact negatively at higher doses to host rohu (Labeo  rohita )