Apteronotus is a genus of weakly electric ghost knifefishes in the family Apteronotidae, distributed through river systems across northern South America; the atlas draws its records from Colombia, Brazil, Venezuela, Peru, Ecuador, Bolivia, French Guiana, and Guyana. Like other apteronotids, Apteronotus lack a true tail fin and propel themselves by rippling a long anal fin that runs most of the length of the underside, allowing forward and backward swimming with equal ease — useful for backing in and out of the crevices, root tangles, and driftwood piles they favor by day. They generate a continuous weak electric field for navigation, prey detection, and communication with other knifefish, a sense well developed for a mostly nocturnal lifestyle in dark, structure-rich water. The atlas covers 31 species with adult sizes from roughly 3–19.5 in.
The genus's best-known member, the Black Ghost Knifefish (Apteronotus albifrons), is one of the most widely kept knifefish in the aquarium hobby worldwide, prized for its sleek black body, pale tail bands, and intelligent, almost eel-like movement. The Brown Ghost Knifefish (A. leptorhynchus and A. rostratus) are also established in the trade. Apteronotus generally do well in a quiet, dimly lit tank with plenty of hiding structure, soft acidic to neutral water, and tankmates that will not out-compete a nocturnal fish for food; they can be territorial toward their own species. Conservation status across the genus is mixed but not alarming overall — the IUCN tally is split fairly evenly between Least Concern and Data Deficient, with only a small number of more range-restricted species rated Vulnerable, Endangered, or Critically Endangered.