Acute toxicity of copper sulphate to the African catfish (<i>Clarias gariepinus</i>) fingerlings

Abstract

Copper sulphate is an important fungicide used in aquaculture. This study aimed to determine the safe and toxicity values of this fungicide to the African catfish (Clarias gariepinus) fingerlings. These catfish fingerlings (mean weight 2.5±0.2 g and mean length 8.11±0.2 cm) were exposed to acute concentration of copper sulphate (CuSO4.5H₂O) for 96 hours. The median lethal concentration (96 hrLC₅₀) values with the lower and upper limits of toxicities were: 2.14 g/L, 3.00 g/L and 4.97 g/L) respectively. The safe level was 2.00 g/L. Statistical analysis of data collected on water quality parameters revealed a significant difference between the 96 hrLC₅₀ at p2). Temperature, pH and acidity were not significantly different at (p>0.05). During the exposure period, the fish showed such signs as increased opercula movement, darkening of the skin, hyperventilation, secretion of mucus, quick jerky movement and no response to gentle prodding before death finally occurred. The results indicated that even though CuSO₄.5H₂O is an important fungicide for aquaculture, it should be applied at the appropriate dose as recommended by manufacturers with caution to avoid environmental consequences.

Key Words: Lethal concentration, fungicide, toxicity, fingerlings, Clarias gariepinus