Aphyocharacidium is a genus of small characins in the tetra group, found in the Amazon basin and neighbouring drainages - the atlas records it from Bolivia, Brazil, and Guyana. It is a genuinely tiny genus: atlas species measure only about 1.5 in, placing them among the smallest characins on the site. Like many diminutive Amazonian tetras, they are slender-bodied, translucent-finned fish that shoal over leaf litter and submerged wood in slow, blackwater-influenced streams, feeding on small invertebrates and drifting organic matter.
This is mostly a genus of scientific rather than hobby interest - data are sparse on either species reaching the aquarium trade with any regularity. A. melandetum, the blackline tetra, is the more distinctively marked of the two, with the dark lateral stripe common to many small tetra species; A. bolivianum is essentially undocumented outside taxonomic literature. Conservation status is split between the two atlas species, one Least Concern and one Vulnerable, hinting at localized pressure on at least part of the genus's range even where broader survey data remain thin.