Rio Jacuizinho is a river located in Rio Grande do Sul, the southernmost state of Brazil. It flows through a region characterized by the subtropical landscapes typical of southern Brazil and is a tributary within the broader Jacuí river basin, eventually contributing to the complex hydrological network that includes the Lagoa dos Patos system. The river passes through agricultural and natural areas of the state's interior, offering anglers access to a diverse assemblage of native freshwater fish species representative of subtropical South American river systems.