The Rio Gurupi is a significant river forming the natural boundary between the states of Pará and Maranhão in northern Brazil, flowing through the Amazon biome and draining into the Atlantic coast. This river system passes through a region of remarkable biodiversity, situated at the transition zone between Amazonian rainforest and other major Brazilian biomes. The river basin is characterized by the lush, dense vegetation typical of the Amazon region, with forested banks and the rich aquatic ecosystems that define Amazonian river systems. As a coastal drainage river, the Gurupi flows through lowland terrain before reaching the sea, creating a diverse range of aquatic habitats that support a variety of fish species. The river has been documented as a type locality for several fish species, underscoring its biological significance within the broader Amazon basin context.