Effect of water-borne copper on Baha'i loach (Turcinoemacheilus bahaii) metabolism

Heavy metals can produce various pathophysiological effects in aquatic animals. In this study, the effect of different water-borne copper concentrations on bahaii loach (Turcinoemacheilus bahaii) metabolism was investigated. Lethal concentration (LC50-96h) of copper was determined for this species according to OECD, 203 protocols. Based on LC50-96h (1.189 mg/l), 40 fish (1.6±0.56 g) were divided into five different groups, including control and different concentrations of copper (24h, 0.910 mg/l), (7d, 0.455 mg/l), (14d, 0.182 mg/L) and (30d, 0.091 mg/l). Then, by using intermittent- flow respirometer, the oxygen consumption of each individual fish was recorded to calculate standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS). Results showed significant (P<0.05) reduction in SMR of fish, exposed to copper. The minimum SMR was obtained following 30days exposure to copper (43.90 ± 14.86 mgO2/kg/h), which was reduced by about 70%, as compared to control group (148.10 ± 12.73 mgO2/kg/h). Although MMR were remained unchanged following all copper treatments, AS in copper-treated fish (14d) showed a significant increase (P<0.05) in comparison with control group. According to the results, it seems that copper could disrupt fish metabolism and subsequently, changes the energy budget of fish, required for biological activities such as growth, feeding and reproduction.