Rio Trairi is a coastal river system flowing through Rio Grande do Norte state in northeastern Brazil. The basin extends from upper freshwater stretches down through a lower estuarine zone before reaching the Atlantic coast, passing through a diverse range of habitats that support a rich and varied fish community. The river drains through the Caatinga biome and transitions into Atlantic Forest near its lower reaches, creating a dynamic mix of freshwater, brackish, and estuarine environments that attract both resident and migratory fish species. The Papari lagoon is closely associated with the lower portion of the basin and adds significant habitat diversity to the system.