Adontosternarchus is a genus of ghost knifefish in the family Apteronotidae, found in the Amazon and Orinoco basin drainages of Brazil, Venezuela, Peru, and Ecuador. The genus name reflects a real anatomical trait — these fish lack the teeth found in many of their apteronotid relatives — and like other ghost knifefish they are weakly electric, generating a continuous electric organ discharge that they use to navigate, sense their surroundings, and communicate in the dark, often turbid water of Amazonian river channels at night. The atlas covers 6 species, from about 7.5 in up to over 12.5 in as adults.
Common names in the atlas — the Marble knifefish (Adontosternarchus balaenops) and Clouded ghost knifefish (A. nebulosus) — describe two of the more recognisable species, but the genus as a whole is far less familiar to aquarists than its relative the black ghost knifefish, and is mostly of interest to researchers studying weakly electric fish and their electroreception. All six species assessed in the atlas carry a Least Concern rating, a comparatively clean conservation picture for a genus tied to the wide, still largely intact river channels of the Amazon and Orinoco systems.