Short term effects of copper on serum osmolality and ions levels of tilapia oreochromis niloticus

Effects of copper on serum osmolality and ion levels of tilapia (O. niloticus) were evaluated after 96 h of exposure. Serum osmolalities (SOs) in fish unexposed to Cu (0 mg/L) and exposed to 1 mg Cu/L were not significantly different, while in fish exposed to 5 mg Cu/L, SO was significantly lower than those exposed to 0 and 1 mg Cu/L. Levels of Na⁺ and Cl^– in serum of fish exposed to 0, 1 and 5 mg Cu/L were not significantly different. The highest level of K⁺ in serum occurred in fish exposed to 5 mg Cu/L, whereas levels of K+ in fish exposed to 0 and 1 mg Cu/L were not significantly different.