Rachoviscus is a small genus of characins native to coastal river drainages in Brazil. The genus's 2 species in the atlas are small, 1.5–2 in, with the slim body and forked tail typical of tetra-like characins, and both carry descriptive common names reflecting head and fin shape - the cherryfin tetra (Rachoviscus crassiceps) and the slender-headed tetra (R. graciliceps). The genus has had a somewhat unsettled taxonomic history, having at times been treated as a distinct lineage within the characins rather than grouped with more familiar tetra genera.
Both species are part of the atlas's CARES priority list, the conservation-breeding program aimed at range-restricted or threatened fish that depend on hobbyist populations as a hedge against wild decline, reflecting real concern for the genus's status - one species has not yet been formally evaluated by IUCN and the other is assessed Endangered. Little detailed husbandry information circulates in the mainstream hobby literature, and specimens are seen mainly among dedicated South American characin keepers rather than in general trade.