Evaluation of Effects of Copper Sulphate and Ferrocene on Nile Tilapia Oreochromisniloticus(L.) Fingerlings

This study was carried out to evaluate the response of Nile tilapia (Oreochromisniloticus) fingerlings to acute copper sulphate and ferrocene toxicity. Nile tilapia fingerlings weighing 2.3 ±0.2g were acclimated and randomly distributed at a rate of 10 fish per 30 L aquarium. Fish were exposed to a range of copper sulphateand ferrocene concentrations of 4mg/L, 8mg/L, 12mg/L,16mg/L and 2.5mg/L, 5mg/L, 7.5mg/L,10mg/L respectively. Fish not exposed to any toxicant served as control. Mortality was assessed and median lethal concentration (LC₅₀) and median lethal time (LT₅₀) were calculated. The 96-h LC₅₀ values obtained for copper sulphate and ferrocene were 7.49mg/L (confidence interval CI: 6.35 to 8.57 mg/L) and 3.55 mg/L (CI: 0.98 to 5.17 mg/L) respectively. The LC₅₀ decreased with time of exposure implying that toxicity increased over time, however, LT₅₀decreased as concentration increased. The safe concentration for copper sulphate derived was 1.913mg/L and 1.196mg/L for ferrocene. Histological analyses were carried out on fish gills and skin. The skin histomorphology showed marked and widespread epidermal loss and widespread mycocytic degeneration in treatments with high concentration for both toxicants. The gill morphology showed moderate to severe hyperplasia of the primary gill epithelia leading to partial or complete loss of the secondary lamellae.