The Igarapé Tarumã-Mirim is a blackwater river located in the state of Amazonas, Brazil, forming part of the vast Rio Negro basin. Characteristic of the region, its waters are acidic, stained dark by tannins from decomposing vegetation, and are notably low in dissolved minerals. The river experiences a significant seasonal fluctuation in water level, typically rising and falling between 1.5 to 3 meters (approximately 5 to 10 feet) annually, with the highest water levels occurring around June. This dynamic environment is home to unique aquatic life, including a recently discovered and scientifically significant fish species.