The Rio Ceará Mirim is a river system flowing through the state of Rio Grande do Norte in northeastern Brazil, draining into the Atlantic coast through a biologically rich estuary. The basin supports a diverse ichthyofauna, with the estuary alone harboring the majority of the basin's documented native fish species, making it a particularly productive zone for anglers. The river transitions from freshwater reaches in its upper and middle sections to brackish and estuarine environments near the coast, creating a variety of fishing habitats and opportunities for targeting different species depending on where you fish along its length.