Lebiasina is a genus of characiform fishes in the pencilfish family Lebiasinidae, a relative of the small aquarium favorite Nannostomus but generally larger and more elongated, with an upturned mouth and a torpedo-shaped body built for holding station in slow, shaded forest streams. The atlas covers 26 species, from about 1.5–6.5 in, distributed across northern and western South America and into Central America: Colombia, Venezuela, Ecuador, Brazil, Peru, Guyana, Panama, and Costa Rica. Like other lebiasinids, they are thought to tolerate low-oxygen, blackwater conditions better than most characins, suited to the swampy, leaf-littered habitats many species occupy.
Lebiasina has little presence in the mainstream aquarium trade; only a handful of species, such as the twospot lebiasina (L. bimaculata) and Panama lebiasina (L. panamensis), turn up with any regularity, usually among characin specialists rather than general hobbyists. Most of the genus is better known to ichthyologists than aquarists, and the conservation picture reflects that: the majority of species have not yet been formally assessed, so the honest state of knowledge is that data are sparse rather than reassuring.