Sternarchogiton preto is a species of weakly electric knifefish in the family Apteronotidae. It is native to large river channels and major side branches in the Amazon Basin, and is common in the Rio Tefé and the Rio Solimões to a depth of 14 m. It is found in both whitewater and blackwater habitats. The species name preto comes from the Portuguese word for "black", referring to its coloration.