Lepthoplosternum is a genus of armored catfish in family Callichthyidae - the same family as Corydoras, but placed in the hoplosternine lineage of larger, more elongate armored catfish alongside Hoplosternum and Megalechis. It was split out to hold a cluster of smaller Hoplosternum-like species from lowland South America, with the atlas's countries covering Brazil, Peru, Argentina, Bolivia, and Paraguay. Atlas species are compact, 2–2.5 in, built along the same two-row bony-plated body as their Corydoras relatives but more elongate and slab-sided, suited to slow, often oxygen-poor floodplain and lagoon waters.
Like other callichthyids, Lepthoplosternum species are facultative air-breathers, gulping atmospheric air and absorbing oxygen through a modified, highly vascularized gut wall - an adaptation that lets them survive in stagnant, hypoxic pools where most fish cannot. Species carry regional names reflecting that habitat, such as the lagoon catfish (L. tordilho) and the Portuguese tamboatá (L. pectorale), and the genus is more a subject for specialist catfish keepers than the mainstream trade. Conservation status is comfortable overall - 4 of the 6 atlas species are Least Concern - though one is Near Threatened, a status worth watching given how tied these fish are to floodplain wetlands under agricultural pressure.