Thoracocharax is a genus of freshwater hatchetfish in the family Gasteropelecidae, instantly recognizable by a deep, keel-like chest that houses an enlarged set of muscles used to power short bursts of flight above the water's surface. The atlas's two species, Thoracocharax securis (the giant hatchetfish) and T. stellatus (the spotfin hatchetfish), range widely across South American lowland drainages spanning Argentina, Bolivia, Brazil, Colombia, Ecuador, Peru, Venezuela, and Paraguay, and grow to 2.5–3.5 in, large for a hatchetfish.
In the aquarium hobby, hatchetfishes of this genus are kept as surface-dwelling schooling fish, best appreciated in groups in a well-covered tank, since their strong escape jumps and short glides can easily take them clear of an open aquarium. They favor slow-moving, well-planted or shaded water near the surface in the wild and tend to be somewhat more delicate and skittish than smaller tetras kept in the same setups. Both species are currently considered secure, with Thoracocharax stellatus assessed as Least Concern and T. securis not yet formally evaluated.