The Golfão Maranhense is an extensive estuarine complex on the eastern Amazon coast of northern Brazil, in the state of Maranhão. This vast tidal system is characterized by a semi-diurnal tidal regime, creating a dynamic environment of brackish waters where marine and freshwater influences mix. It functions as a critical nursery ground and habitat for a wide diversity of fish species, supporting significant ichthyofaunal diversity. The system communicates directly with the Atlantic Ocean, forming a complex network of channels, bays, and intertidal zones that define the region's rich fishing opportunities.