120 Nile tilapia were divided into four groups, the first group (G1) was fed on a commercial diet (control group), the second group (G2) was fed on commercial diets supplemented with vitamin E (Vit E, 600 mg /kg diet), the third group (G3) was fed on commercial diet and exposed to Copper sulfate pentahydrate (CuSO4. 5 H2O) at a dose of 0.32 of mg/L. The fourth group (G4) was fed on a diet supplemented with Vit E (600 mg/ kg diet) and exposed to 0.32 of CuSO4 mg/L. At the end of the feeding trial, fish were challenged by intraperitoneal injection of 0.1 ml dose of virulent Aeromonas hydrophila (5 x 10⁵ CFU/ fish). Blood samples and tissue samples were collected after (10, 20 and 30 days) of treatment and a week post-challenge. Fish exposed to CuSO4 exhibited a significant decrease in the weight gain, relative body weight gain and feed efficiency ratio, while significantly increased in fish exposed to CuSO4 and given Vit E. Furthermore, cumulative mortality was high in challenged fish exposed to CuSO4. Fish exposed to CuSO4 exhibited a significant decline in red blood cell count, hemoglobin concentration, packed cell volume and serum immunoglobulin M pre and post-challenge throughout the experiment. However, white blood corpuscles count, lymphocytes and neutrophils count increased in fish exposed to CuSO4 pre and post-challenge. CuSO4 exposure induced a significant increase in serum alanine aminotransferase, aspartate aminotransferase, creatinine and hepatic antioxidants; superoxide dismutase and catalase levels pre and post- challenge of Nile tilapia throughout the experiment, while glutathione level was significantly decreased. CuSO4 exposure induced degenerative changes in the liver, while the kidneys revealed highly dilated capillaries and degenerated renal tubules and round cell aggregations in the gill arches beside marked mucinous degeneration in the gill filaments were seen. The obtained findings also revealed the protective effect of Vit. E against copper sulfate toxicity and fish susceptibility to Aeromonas hydrophila challenge through enhanced growth performance, immune response, hemato-biochemical parameters and increased antioxidants activities. The lowest mortality and pathological lesions were recorded in fish treated with Vit. E.