The Rio Itabapoana is a significant river system in southeastern Brazil, forming the natural geographic boundary between the states of Espírito Santo and Rio de Janeiro. Draining a basin of approximately 1,523 square kilometers, this river is part of the broader Atlantic Forest hydrographic network and represents one of the region's most ecologically important freshwater systems. The river flows through a landscape shaped by the Atlantic Forest biome, connecting upland headwaters to the coastal lowlands before reaching the sea. Its position as a biogeographic divide gives it a unique character, with fish communities that reflect both the southern Espírito Santo ichthyofauna and the lower Rio Paraíba do Sul bioregion, making it a river of considerable interest to anglers and naturalists alike.