Sternarchogiton

The Natterer’s Knifefish (Sternarchogiton nattereri) is extremely rare species of knifefish is found throughout much of the middle Amazon, where it inhabits mats of floating vegetation in low to moderate flow areas and feeds primarily on insect larvae. Adult males of the species develop a jaw full of huge, protruding teeth and were once thought to represent another genus and species entirely (Oedemognathus exodon). Males are thought to use these teeth in territorial disputes against other adult males, although the species is generally peaceful toward one another so long as they are provided with ample hides and cover.