Accumulation of copper in Clarias anguillaris L. and Oreochromis niloticus L.

Abstract

Clarias anguillaris and Oreochromis niloticus were each exposed to solutions of Analar grade Cu sulphate in static bioassays at a temperature range of 20 to 23.5°C and CaCO3 hardness of 30 to 44 mg L−1. Copper accumulation was determined by Atomic Absorption Spectroscopy. The Cu residues in Clarias anguillaris exposed to 0.027, 0.055, and 0.11 mg Cu L−1. for 8 weeks were 15.7, 21.8, and 31.17 mg g−1 dry weight, respectively. Oreochromis niloticus exposed to 0.05, 0.1 and 0.2 mg Cu L−1. accumulated 34.69, 36.09, and 81.03 mg g−1 dry weight, respectively, over the 8-week period of exposure. The lowest and highest bioconcentration factors (BCF) were 117 and 581 for Clarias anguillaris and, 176 and 694 for Oreochromis niloticus. Copper concentrations in tissues of both species were directly related to the exposure concentrations and the duration of exposure. Increased accumulation towards the last 2 weeks of exposure may be due to impaired capacity of elimination or poor nutritional status.