Rio das Mortes is a tributary of the rio Grande, originating in the southeastern corner of Minas Gerais, Brazil, within one of the most biogeographically complex highland regions on the continent. The river's headwaters rise in the Serra da Mantiqueira and the Espinhaço range complex — a rugged, elevated landscape where four major Brazilian hydrographic systems converge in close proximity: the rio São Francisco, the upper rio Paraná, the rio Doce, and the rio Paraíba do Sul. This geological and hydrological crossroads gives the rio das Mortes and its surrounding watershed an exceptional level of aquatic biodiversity, including several fish species found nowhere else on Earth. The river flows through a landscape shaped by ancient mountain ranges, and its headwater streams in particular harbor a remarkable assemblage of native catfishes and other endemic species that reflect millions of years of isolated evolution in these highlands.