Fish fauna in a tributary stream of a Neotropical reservoir

Little is known about the fish diversity of streams that flow into Neotropical reservoirs. This is a special case of tributary streams flowing into reservoirs of the Paraná River basin in Brazil. In this study, we sampled a tributary stream of Jurumirim reservoir to understand its fish diversity. We sampled bimonthly from April to December 2022 at four sites in the Pedra Preta stream. We found a total of 1,492 individuals of 31 fish species. We discovered that six native migratory species (i.e., Steindachnerina insculpta, Brevidens striatus, Psalidodon bockmanni, P. fasciatus, Astyanax lacustris, Pimelodus maculatus) occur in the Pedra Preta stream. These species may be using the Pedra Preta stream to reproduce and can return to the Jurumirim reservoir in different phases of their life cycle, since both environments (i.e., watercourse and the artificial lake) are connected. Our study reinforces the need for a better understanding of each tributary stream of Neotropical reservoir. In addition, we suggest that, due to the high species richness found in our study, tributary streams of reservoirs should be considered as targets for preservation.