Effects of Copper on Haematological Parameters in the African Freshwater cichlid, <i>Oreochromis Urolepis</i>

Abstract

The effect of copper on blood parameters in the African freshwater Cichlid Oreochromis urolepis were investigated. This was an experimental study conducted in the aquaria in the Department of Zoology and Wildlife Conservation, University of Dar Es Salaam. Exposure of Oreochromis urolepis to different concentration of copper for a period of up to 35 days, at average water temperature 25ºC, dissolved oxygen 5.4mg/l and pH 6.7, revealed a significant change in some heamatological parameters. For example, Red blood cell counts (RBC) in fish exposed at 100, 150 and 200μgCu/l increased significantly on day 7. Packed cell volume (PCV), Mean Corpuscular Haemoglobin Concentration (MCHC), Mean Corpuscular Haemoglobin (MCH), and Mean Corpuscular Volume (MCV) significantly changed with increasing copper concentration and exposure time. Plasma sodium ion concentration [Na+] was significantly altered on day 2, in all copper exposed fish. Chloride ions significantly decreased in higher exposures and increased, on day 35. No significant changes were observed in plasma Ca+2 in all exposed fish. Potassium ions significantly increased only in fish exposed to higher copper concentration. It is recommended that copper at lower concentrations of up to 50μg/l can be used in aquaculture for a short period without causing any significant heamatological changes in the cultured fish.

Keywords: Copper, haematological parameters, Oreochromis urolepis.