Bario is a genus of small characid tetras from South America, and the atlas's five species cover an unusually wide range for so small a genus - Brazil, Argentina, Paraguay, Peru, Uruguay, Bolivia, French Guiana, and Guyana - touching the Amazon, Parana-Paraguay, and Guiana Shield systems. At 2.5–4 in, these are modestly sized, laterally compressed, silvery schooling fish typical of the smaller tetra genera scattered through family Characidae, generally found in flowing forest streams rather than still water.
Common names recorded for atlas species - among them 'Southern Moenkhausia' and 'Glass Tetra' for Bario australis and Bario oligolepis, and 'Red-eye tetra' for Bario sanctaefilomenae - echo other, better-known tetra genera, a reminder of how visually similar many small silver characids are and how often their common names get borrowed across genus lines. Bario itself is a minor presence in the aquarium trade rather than a hobby staple; where it is kept, it behaves like most small stream tetras, doing best in a peaceful school in soft, slightly acidic water. With three Not Evaluated species alongside one Least Concern and one Data Deficient, data on this genus are genuinely sparse.