Rio Pajeú is a river flowing through the Sertão region of Pernambuco, Brazil, winding through the semi-arid Caatinga landscape of the Brazilian Northeast. As a tributary of the São Francisco basin, the river is deeply embedded in the ecology and culture of the region, passing through the municipality of Serra Talhada and surrounding communities. The river traverses a rugged, sun-baked terrain characteristic of the Caatinga biome — one of the world's most biodiverse semi-arid ecosystems — where rainfall is seasonal and highly variable, directly influencing water levels and fish behavior throughout the year. The river's character shifts dramatically between the wet and dry seasons, transitioning from a flowing, connected waterway during the rainy months to a series of isolated pools and slower stretches during the dry season, concentrating fish and creating unique angling opportunities.