Balsas River

The Balsas River (locally known as the Mezcala River or Atoyac River) is a major river of south-central Mexico.

The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Altamirano, Guerrero, it forms the border between Guerrero and Michoacán. The river flows through the Sierra Madre del Sur, and empties into the Pacific Ocean at Mangrove Point, adjacent to the city of Lázaro Cárdenas, Michoacán.

Several rapids along the course of the Balsas River limit its navigability and thus the river has been largely used for generation of hydroelectric power, flood control and irrigation.

Seven endemic fish are found in the Balsas ecoregion. These are the Balsas splitfin (Ilyodon whitei), the Catarina allotoca (Allotoca catarinae), the Balsas livebearer (Poeciliopsis balsas), the Balsas molly (Poecilia maylandi), the Balsas silverside (Atherinella balsana), the Balsas catfish (Ictalurus balsanus), and the Balsas shiner (Hybopsis boucardi).

This ecoregion does not have the richness of cichlid species that most of southern Mexico exhibits. Only one of these fish, the redside cichlid (Cichlasoma istlanum), appears in the Balsas ecoregion.