This study aimed to evaluate water quality using limnological parameters in two sub-basins of the Negro and Apa Rivers, along with the composition and structure of the landscape around the locations sampled in the two sub-basins and their possible contribution to the loss of water quality. We also set out to identify the genotoxic effects on the erythrocytes of Prochilodus lineatus and Leporinus friderici. In particular, we quantified total Cr, Ni and Pb in the muscle of these fish species to determine which genotoxic changes are related to the concentration of metals detected in the fish from these two sub-basins of the Paraguay River Basin. The sub-basin of the Apa River presented a greater proportion of surrounding pastureland in relation to the basin of the Negro River. The erythrocytes of P. lineatus showed a significant difference between the sub-basins for nuclear pyknosis, binucleated cells and lobed nuclei (p < 0.05). In L. friderici, vacuolated nuclei, nuclear pyknosis and lobed nuclei alterations also showed a significant difference between the sub-basins (p < 0.05). The genotoxicity index of the Apa River sub-basin presented higher frequencies of nuclear alterations in P. lineatus and L. friderici (p < 0.05), compared to the Negro River sub-basin. The concentration of total Cr, Ni and Pb in the muscles of P. lineatus and L. friderici in the Negro River sub-basin leads to genotoxic damage, mainly from the induction of lobed nuclei. Based on our results, it can be concluded that toxicogenetic effects in native fish species are an important source of environmental diagnosis in the Upper Paraguay River Basin.

本研究旨在使用内格罗河和阿帕河两个子流域的湖泊参数评估水质，以及两个子流域采样位置周围景观的组成和结构及其对水流失的可能贡献质量。我们还着手确定对Prochilodus lineatus和Leporinus friderici红细胞的遗传毒性影响. 特别是，我们量化了这些鱼类肌肉中的总铬、镍和铅，以确定哪些遗传毒性变化与巴拉圭河流域这两个亚流域的鱼类中检测到的金属浓度有关。与内格罗河流域相比，阿帕河流域的周边牧场占更大比例。P. lineatus的红细胞在核固缩、双核细胞和裂核亚池之间表现出显着差异（p <0.05）。在L. friderici中，空泡化核、核固缩和裂核改变也显示出亚盆地之间的显着差异（p <0.05）。阿帕河次流域的遗传毒性指数表现出较高的核改变频率与内格罗河流域相比，P. lineatus和L. friderici (p < 0.05)。内格罗河亚流域P. lineatus和L. friderici肌肉中总 Cr、Ni 和 Pb 的浓度导致基因毒性损伤，主要来自叶状核的诱导。根据我们的结果，可以得出结论，本地鱼类的毒物发生效应是巴拉圭河流域上游环境诊断的重要来源。