Papyrocranus is a genus of African featherback knifefish in family Notopteridae, the same family as the more familiar Old World knifefishes. The atlas's two species range across West and Central Africa, from Senegal and Gambia through Ghana and Nigeria to Cameroon and the Congo basin. They share the knifefish body plan: a long, laterally compressed, blade-like body that tapers to a point, with the anal and caudal fins fused into a single fin ribbon running most of the fish's length and no distinct dorsal fin to speak of. Atlas sizes run from about 11.5 in up to 31.5 in, so a Papyrocranus can grow into a genuinely large aquarium or pond fish.
Both species - the reticulated knifefish (P. afer) and the Congo black knife (P. congoensis) - turn up in the aquarium trade as striking, if slow-moving, oddball fish prized for their reticulated or mottled patterning and their unusual swimming style, undulating that long fin ribbon to hover, hold position, and even swim in reverse. Like other notopterids they are largely nocturnal predators that rely on air-gulping to supplement gill respiration in oxygen-poor swamp and floodplain water, and both are currently assessed as Least Concern, a healthier conservation picture than many African freshwater fish enjoy.