Rio Preto is a river located in the state of São Paulo, Brazil, flowing through the northwestern portion of the state within the upper Paraná River basin. The river is notable for its remarkable biodiversity, supporting a rich and diverse ichthyofauna that reflects the ecological complexity of the broader Paraná drainage system. The lower reaches of the river pass near the municipality of São José do Rio Preto, where a dam and its associated spillway create distinct upstream and downstream environments, each with its own fish community characteristics. The river supports at least 69 documented fish species across 16 families and seven orders, making it a genuinely productive and ecologically significant fishery for anglers interested in tropical freshwater species.