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.

[1][2] 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.

[2][3] Eigenmannia are often found near submerged roots, aquatic plants and floating meadows.

[3][4] Depending on the exact species, they have a maximum total length of 14.3–49.6 cm (6–20 in).

[1] They are nocturnal, and feed on small invertebrates such as aquatic insect larvae and zooplanktonic crustaceans.