The Rio Sapucaí-Mirim is a significant river system flowing through the states of Minas Gerais and São Paulo in southeastern Brazil, originating high in the Mantiqueira Mountains at an elevation of approximately 1,950 meters (6,400 feet) above sea level. Over its roughly 150-kilometer (93-mile) course, the river descends dramatically to around 800 meters (2,600 feet) at its mouth, where it joins the Sapucaí River. This substantial elevation gradient creates a diverse range of aquatic habitats — from cool, fast-moving mountain headwaters to slower, warmer lowland stretches — supporting one of the most ecologically rich fish communities in the upper Paraná River basin. The river ultimately drains into the Grande River system, with its lower reaches influenced by the reservoir of the Porto Colombia hydroelectric power plant near the São Paulo state border. With 68 documented fish species across 23 families, the Rio Sapucaí-Mirim offers anglers an exceptional diversity of target species in a relatively underexplored setting.