Odontocharacidium is a genus of tiny characiform fish from blackwater and clearwater streams across the Amazon and Orinoco basins, found in Venezuela, Brazil, Colombia, and Peru. Its species are among the smallest characiforms in the atlas, at only around 0.5–1 in as adults - diminutive fish adapted to life among leaf litter and fine submerged vegetation in soft, often acidic water. The atlas covers 2 species, Odontocharacidium aphanes and O. varii.
O. aphanes, the green dwarf tetra, occasionally reaches specialist aquarium circles as a nano-tank fish for keepers set up to replicate soft, tannin-stained blackwater conditions, though it is not a mainstream trade species; O. varii is essentially unknown outside the scientific literature. Given the genus's tiny size and specialised habitat needs, data on captive care are sparse. One species is assessed as Least Concern and the other has not yet been formally evaluated.