Chronic dietary exposure to copper affects growth, tissue lipid peroxidation, and metal composition of the grey mullet, Chelon labrosus

Juvenile grey mullet (Chelon labrosus) were fed either a basal (4.4 mg Cu/kg dry wt) or high-Cu diet (2400 mg Cu metal/kg dry wt) for 10 weeks to assess the relationship between growth and Cu-induced oxidative damage. No mortalities were observed, but growth rate and food intake were reduced by 43 and 29%, respectively, in the high-Cu group. This was not only attributed to peroxidative damage of the food which reduced food intake (palatability), but also to direct effects of hepatic lipid peroxidation. Hepatic α-tocopherol concentrations were 63% lower, while malondialdehyde (MDA) increased by 304% in mullet fed a high-Cu diet for 67d. Cu-exposure reduced apparent α-tocopherol retention by 420%. Hepatic Fe and Zn levels fell, while Cu increased (p < 0.05). The results show that oral Cu exposure induces oxidative stress in grey mullet. Quantification of lipid peroxidation (rancidity) in the food, reflecting palatability, is essential to differentiate the direct toxic effects of Cu on growth from the secondary influences of reduced food intake.