Rio Piuí (also spelled Piumhi) winds through the middle-west region of Minas Gerais, Brazil, originating in the highlands between the cities of Vargem Bonita and Piumhi at an elevation of approximately 930 meters. This river carries deep historical significance — early explorers specifically noted the Piuí as standing apart from neighboring waterways like the São Francisco, Rio Grande, Lambari, and Rio Verde due to its exceptional fish population. The river's name itself reflects this legacy, derived from Old Tupi roots meaning either "river of black flies" or "fish river," a testament to its long-recognized productivity as a fishery. The river's course and watershed were dramatically altered in the early 1960s when the construction of the Furnas Hydroelectric Power Dam on the Rio Grande prompted an artificial transposition of the Piuí's drainage, redirecting waters that had historically flowed toward the Paraná basin into the São Francisco system — an event considered one of the most significant watershed transpositions in eastern Brazil, with lasting consequences for the region's fish fauna.