Moenkhausia is a large genus of characid tetras from tropical South America, ranging through Brazil, Colombia, Peru, Venezuela, Suriname, French Guiana, Guyana, and Bolivia. The atlas covers 80 species, from small 1 in forms up to about 4.5 in, occupying the Amazon and Orinoco basins and the rivers of the Guiana Shield. Like most characids, Moenkhausia species are laterally compressed, silvery-bodied schooling fish with an adipose fin, and many carry a dark spot or bar at the base of the tail along with coloured markings on the fins that help distinguish species in the field.
The genus is a familiar name on the tetra side of the aquarium hobby: species such as the Aurora Tetra (Moenkhausia aurora), Pretty Tetra (M. bonita), Glass Tetra (M. intermedia), and Golden Parakeet Tetra (M. guaruba) are kept for their schooling behaviour and understated colour, and most are undemanding, adaptable community fish that do well in typical soft, warm South American aquarium setups. Diet is omnivorous in both wild and captive settings, taking small invertebrates, algae, and plant matter.
Conservation status across the genus is comparatively reassuring: the majority of assessed species come back Least Concern, with only a single Near Threatened listing and nothing currently assessed above that level in the atlas, though a substantial share remain Not Evaluated or Data Deficient simply because the genus is large and some species are known from very few records.