Ingestion of sub-lethal levels of iron sulphate by African catfish affects growth and tissue lipid peroxidation

In order to determine the effect of increased iron intake on growth and lipid peroxidation criteria in fish, African catfish (Clarias gariepinus) juveniles of mean weight 32.25 g were fed a ration of 2% body-weight per day, for 5 weeks on fishmeal-based diets containing either 663.5 +/- 56.4 or 6354.4 +/- 70.3 mg iron per kg dry diet (supplied as FeSo(4) . 7H(2)O). Ingestion of the higher dietary iron ration resulted in suppressed growth (p < 0.05) in catfish, implying that the metal was supplied at toxic levels, though tissue concentrations of the metal were unaffected by dietary regime (p > 0.05 for muscle, liver and plasma) and haematocrit values were not significantly different between treatments (p > 0.05). Despite this, concentrations of the lipid peroxidation product malondialdehyde (MDA) in liver and heart increased concomitant with dietary iron dose (p < 0.05) indicating heightened oxidative stress in catfish consuming diets high in iron. Additionally, assayed levels of the fat-soluble antioxidant vitamin, vitamin E (alpha-tocopherol) were significantly depleted (p < 0.001) in livers from these fish, thus demonstrating tocopherol use under conditions of dietary oxidant overload and revealing hepatic vitamin E status to be a useful bioindicator of chronic iron exposure. (C) 1997 Elsevier Science B.V.