Eigenmannia is a genus of fish in the family Sternopygidae (glass knifefishes) native to tropical and subtropical South America (south to the Río de la Plata Basin), and Panama. They are typically found in slow-flowing streams, along the edge of large rivers, in deep river channels and in floodplains, and the genus also includes E. vicentespelaea, the only cave-adapted knifefish. Eigenmannia are often found near submerged roots, aquatic plants and floating meadows.

Depending on the exact species, they have a maximum total length of . They are nocturnal, and feed on small invertebrates such as aquatic insect larvae and zooplanktonic crustaceans.

Species: , these are the recognized species in this genus: