Pariosternarchus amazonensis is a little-known species of weakly electric knifefish in the family Apteronotidae, and the only member of its genus. It is found in the main channel of the Amazon River in Brazil and Peru, likely near the bottom in deep, fast-moving water. This species is characterized by a wide head with a flat bottom, and very large sensory canals along the lower jaw. Like several other knifefishes found in deep river channels, it has reduced eyes, scales, and body pigmentation.