Mitigating Effect of Vitamin-E on Copper Sulphate-Induced Toxicity in African Catfish (Clarias gariepinus)

Abstract

Copper sulphate is widely used not only in livestock production especially in the treatment of foot rot in small ruminants but also in aquaculture as algaecide and an ectoparasiticide in hatcheries. Meanwhile, it is a common environmental contaminant of water bodies, with carcinogenic, mutagenic and teratogenic effects in humans and animals. The present study was therefore designed to evaluate the toxic effects of copper sulphate and the protective activities of vitamin E on haematological and biochemical parameters as well as oxidative stress status in the African catfish (Clarias gariepinus) Sixty juvenile African catfish with an average weight of 120g were used for the study. They were assigned into six groups (A-F) consisting of ten fish per group. Group A served as the control group and was fed with normal pelletized fish feed only, group B was fed with Vitamin E-supplemented feed only, groups C and D were exposed to copper sulphate (20mg/L and 5mg/L) respectively, plus normal pelletized fish feed while groups E and F were exposed to copper sulphate (20mg/L and 5mg/L), respectively, plus Vitamin E-supplemented feed (240mg/kg feed). Blood samples were collected for haematology and plasma biochemical parameters while gills, liver and kidney samples were collected for evaluation markers of oxidative stress. Exposure to copper sulphate led to a significant decrease in PCV, RBC, Hb concentration, MCV, MCH and total WBC when compared with the unexposed control and those fed with vitamin E-supplemented feed. Furthermore, exposure to copper sulphate caused liver and kidney damages and cell impairment by increasing plasma ALT, AST and ALP activities. It also led to increased oxidative stress as the concentrations of antioxidant endogenous enzymes - GPx, GST and GSH were depleted while potentiating lipid peroxidation and hydroxyl radical generation. The changes in the haematological, biochemical and antioxidant parameters were restored in the fish fed with vitamin E-supplemented feed. In conclusion, the study showed that exposure to copper sulphate is toxic to African catfish, causing anaemia and liver damage through free radical generation and depletion of antioxidant defence system. Vitamin – E supplementation is therefore recommended during the use of CuSO4 in aquaculture. Release of the compound to the environment must however be avoided at all cost.