Urban sewage is a source of major contamination in aquatic systems and contributes to environmental and human health disturbances. This study investigates the effects of sewage-polluted waters from Iguaçu River on the health of juvenile Oreochromis niloticus. Two hundred four specimens were exposed to riverine water in four groups: no diluted, 25 and 50 % diluted water and a control group without tested water for 72 days. Biological samples were obtained for histopathological, neurotoxicity, antioxidant defenses, genotoxicity, metallothionines expression and polycyclic aromatic hydrocarbons (PAHs) metabolites. The results showed histopathological alterations in liver and gills, genotoxic alteration in erythrocytes, reduction of acetylcholinesterase activity in brain and muscle, activation of antioxidant defenses in the liver, recruitment of metals by metallothionein and the detection of PAHs metabolites in bile. These results demonstrate that juveniles of O. niloticus are susceptible to Iguaçu River exposure water and they can be used as indicator of water quality.

城市污水是水生系统的主要污染源，并导致环境和人类健康受到干扰。本研究调查了伊瓜苏河污水污染对尼罗罗非鱼幼鱼健康的影响. 204 个样本分四组暴露于河水：未稀释、25% 和 50% 稀释的水以及未使用测试水的对照组 72 天。获得了组织病理学、神经毒性、抗氧化防御、基因毒性、金属硫氨酸表达和多环芳烃 (PAH) 代谢物的生物样本。结果显示肝脏和鳃的组织病理学改变、红细胞的基因毒性改变、脑和肌肉中乙酰胆碱酯酶活性的降低、肝脏中抗氧化防御的激活、金属硫蛋白对金属的募集以及胆汁中多环芳烃代谢物的检测。这些结果表明，O. niloticus 的幼鱼 易受伊瓜苏河暴露水的影响，它们可用作水质指标。