Carnegiella is a genus of freshwater hatchetfishes in family Gasteropelecidae, within the order Characiformes alongside the true tetras. The atlas covers 4 species, all under 1.5 in, found across the Amazon and Orinoco drainages in Brazil, Colombia, Peru, Bolivia, Ecuador, and Venezuela. Like other gasteropelecids, Carnegiella have a deep, keeled belly and an enlarged pectoral girdle carrying oversized flight muscles, letting them beat their pectoral fins rapidly and skim or glide just above the water's surface — a genuine escape adaptation rare among freshwater fish. They live near the surface of quiet forest streams and blackwater habitat, sheltering among leaf litter and overhanging vegetation, and feed mainly on small insects taken at or above the waterline.
The marbled hatchetfish (Carnegiella strigata) is the species hobbyists are most likely to encounter, a long-standing staple of the peaceful, surface-dwelling schooling-fish trade; the blackwing hatchetfish (C. marthae) and the smaller pygmy and dwarf hatchetfishes (C. myersi, C. schereri) turn up more occasionally, mostly through specialist importers. All four are shy schoolers that do best in soft, acidic, well-covered water — their surface-skimming reflex means an open-top tank is an open invitation to jump. Three of the four species in the atlas carry a Least Concern rating; the fourth has not yet been formally assessed, in keeping with how little survey attention some of these narrow-range blackwater fish receive.