Atlantirivulus is a genus of killifish in family Rivulidae, restricted to coastal drainages of the Brazilian Atlantic Forest - all 4 atlas species are recorded only from Brazil. Unlike the classic annual killifish that live in seasonal pools and lay drought-resistant eggs, most Atlantirivulus species are non-annual, inhabiting small permanent forest streams and surviving as free-swimming adults rather than as diapausing eggs in dried mud. They are small fish, from about 1–2.5 in, with the elongate body, dorsally flattened head, and upward-facing mouth typical of surface-feeding rivulids.
The genus is more a specialist than a mainstream aquarium fish, sought out mainly by killifish hobbyists who keep Atlantic Forest rivulids for their coloration and for the conservation interest of a genus tied to one of the most fragmented forest biomes on Earth. All four species in the atlas - A. depressus, A. jurubatibensis, A. riograndensis, and A. santensis - are currently assessed Least Concern, a comparatively favorable picture for coastal Atlantic Forest fish, though continued habitat loss along Brazil's densely populated coast makes that status worth watching rather than taking for granted.