Rio Ipanema is a small but ecologically significant river flowing through southeastern Brazil in the state of São Paulo, serving as a tributary of the Tietê River basin. Situated in a highly impacted region near the São Paulo metropolitan area, the river holds particular conservation value precisely because of its location amid one of Brazil's most densely developed landscapes. Despite its modest size, Rio Ipanema supports a remarkably diverse fish assemblage, making it a rewarding destination for anglers interested in the rich variety of native Neotropical species characteristic of the upper Paraná River drainage system.