The sub-lethal effects of copper on the humoral, enzymological and histopathological parameters in the teleost fish, Anabas testudineus and the curative capacity of vitamin C were investigated. The 96 hour LC50 value of copper was determined using Probit method and was found to be 1.74 mg/L. Fish blood from two sub-lethal concentrations, vitamin supplemented media and toxicant and vitamin free control were analyzed on 7th, 14th, 21st and 28th day of exposure. The haemoglobin (Hb), haematocrit (Hct), erythrocyte count (RBC) and oxygen carrying capacity were reduced compared to the control values up to the day 21 followed by a significant increase (p< 0.0001) in all test concentrations on the day 28. The microscopic observation of RBCs in higher concentrations and long exposure showed crenation, immature