Effects of copper sulfate on oxidative stress and branchial histology in juvenile Clown Fish Amphiprion percula
The Amphiprion percula clown fish has great economic importance due to its high added value. In aquaculture, copper sulfate (CuSO4) is used to control ectoparasites in fish production systems, such as algaecide and herbicide in ponds. This work aimed to verify the sublethal effects of exposure to concentrations of CuSO4 used to treat ectoparasites, and later recovery in juveniles of clown fish A. percula. In experiment I the fish were exposed for 7 days to three treatments: control, without addition of CuSO4, 0.5 and 1.5 mg/L of CuSO4, followed by another 7 days of recovery, in water without addition of copper sulfate . In experiment II the fish were exposed for 14 days at the same concentrations as in experiment I.In both experiments the treatments were carried out in triplicate and 16 juveniles per tank (15L) were used. Collections were performed on days 7 and 14 in both experiments, to perform biochemical analyzes of lipid peroxidation (TBARS), total antioxidant capacity against peroxyl radicals (ACAP) and activity of the enzyme Glutathione–S–Transferase (GST), and histopathological analyzes in the gills. In experiment I, only a reduction in the ACAP of fish submitted to 0.5mg/L of CuSO4 treatment when compared to control treatments and 1.5mg/L of CuSO4 after the recovery period was demonstrated. The histopathologies found were telangiectasis, lamellar fusion and partial lamellar fusion, with lamellar fusion having a lower occurrence in the 1.5mg/L treatment of CuSO4 compared to the others at the end of recovery.In experiment II, the activity of the GST enzyme was lower in the 1.5mg/L treatment of CuSO4 compared to the control group and in the 0.5mg/L treatment of CuSO4. The histopathologies found were telangiectasis, hyperplasia, chloride cell hyperplasia, partial hyperplasia, partial lamellar fusion and complete lamellar fusion, without showing significant differences between treatments. Therefore, the concentrations of 0.5mg/L of CuSO4 and 1.5mg/L of CuSO4 did not induce histopathological changes or an oxidative stress condition, and are therefore safe for clown fish A. percula.