Inpaichthys is a small genus of characid tetras named for INPA, the Brazilian Amazon research institute involved in describing it, and restricted in the atlas to Brazil. The 4 species are diminutive, 1–2 in, slender-bodied schooling fish typical of Amazonian blackwater and clearwater tributaries, where they shoal in open water over leaf litter and submerged wood in soft, acidic conditions.
The genus is best known in the hobby through the Blue Emperor Tetra (Inpaichthys kerri), a long-standing aquarium staple prized for the violet-blue sheen along its flank and the clear sexual dimorphism between the more intensely coloured male and the plainer female. The Black Arrow Tetra (I. luizae) and Scratched Inpa Tetra (I. parauapiranga) turn up occasionally in specialist imports, while I. nambiquara is little known outside ichthyological collections. Care for the group follows standard soft-water Amazon tetra practice - a peaceful shoaling fish for a planted tank with subdued lighting. Of the 4 species, 3 are Least Concern and 1 is Data Deficient, suggesting no acute conservation alarm but incomplete survey coverage for the less-collected species.