Metynnis is a genus of serrasalmid fish from tropical and subtropical South America. They are herbivorous or omnivorous, and inhabit a wide range of freshwater habitats, ranging from rivers and streams (both fast- and slow-flowing), to floodplains, flooded forests, lakes, pools and reservoirs. They generally reach in standard length, although a few species may reach up to . The genus contains many of the species known as silver dollars in the aquarium trade. Species There are currently 15 recognized species in this genus: Metynnis altidorsalis C. G. E. Ahl, 1923 Metynnis argenteus C. G. E. Ahl, 1923 (silver dollar) Metynnis cuiaba Pavanelli, Ota & Petry, 2009 Metynnis fasciatus C. G. E. Ahl, 1931 Metynnis guaporensis C. H. Eigenmann, 1915 Metynnis hypsauchen (J. P. Müller & Troschel, 1844) (silver dollar) Metynnis lippincottianus (Cope, 1870) (spotted silver dollar) Metynnis longipinnis Zarske & Géry, 2008 (silver dollar) Metynnis luna Cope, 1878 Metynnis maculatus (Kner, 1858) (spotted metynnis) Metynnis melanogrammus Ota, Rapp Py-Daniel & Jégu, 2016 Metynnis mola C. H. Eigenmann & C. H. Kennedy, 1903 Metynnis orinocensis (Steindachner, 1908) Metynnis otuquensis C. G. E. Ahl, 1923 Metynnis polystictus Zarske & Géry, 2008 (silver dollar) References Fish of South America Ray-finned fish genera Serrasalmidae Taxa named by Edward Drinker Cope