Mylossoma is a genus of silver dollars in the piranha family Serrasalmidae, broadly distributed across the Amazon, Orinoco, and Paraná-Paraguay basins - the atlas lists it from Bolivia, Brazil, Venezuela, Argentina, Colombia, Ecuador, Paraguay, and Peru. Atlas species run 8–11 in, deep-bodied and laterally flattened like their close relatives Metynnis and Myloplus, with the rounded, disc-like silhouette that gives the group its common name.
Mylossoma aureum, the silver dollar, is a long-established aquarium fish, kept as a peaceful schooling herbivore in large tanks with tough, fast-growing plants able to withstand its appetite; M. duriventre is traded under the same generic 'silver dollar' name and shares similar care needs. Like most silver dollars they are skittish kept alone but settle well in groups, and they do best on a mostly plant-based diet with some protein. Conservation status is mixed across the genus - two atlas species are Least Concern, one Vulnerable.