The aim of the present study deals with the study of defensive enzymatic and non-enzymatic antioxidants in Labeo rohita fish. Antioxidants and oxidative stress biomarkers assay illustrated significant variation (p<0.05), (p<0.01) and (p<0.001) while measure up by means of control. Status of antioxidant were evaluated as measuring the levels of GST, GR, SOD, CAT, GSH and GPx activities intended for evaluating occurrence of oxidative stress in Labeo rohita fish via revelation to 0.08 and 0.20ppm of mercuric chloride in favor of 15 and 30 days. The oxidative stress biomarkers levels were enhanced subsequent to doses of exposure through an uptrend. The impacts of two 0.08 and 0.20ppm sub lethal doses of mercuric chloride were studies on gills, kidney and liver of Labeo rohita fish in substituted exposure duration significantly.