Aphyosemion is a genus of small, brightly coloured killifish native to the forest streams of Central and West-Central Africa, with atlas records from Gabon, Cameroon, the Republic of Congo, Equatorial Guinea, Nigeria, the Central African Republic, and the Democratic Republic of Congo. The 74 species in the atlas are small fish, mostly 1–3 in, and unlike the well-known annual killifish of the genus Nothobranchius, most Aphyosemion live in permanent forest streams and pools rather than seasonal ones that dry up completely, so their eggs are not built around surviving a long dry season.
Many species carry an elongated, often forked lyretail caudal fin, a trait reflected in common names throughout the genus: the Cape Lopez lyretail (Aphyosemion australe) is one of the most enduringly popular killifish in the aquarium hobby, prized for its ease of care and vivid orange-and-blue males, alongside species such as the Two-banded lyretail (A. bivittatum) and Celia's Lyretail (A. celiae). Killifish specialists keep Aphyosemion in soft, acidic, peat-filtered water and breed them as egg-scatterers over fine plants or spawning mops.
Gabon in particular is a centre of diversity for the genus, with several species described from a single forest stream system. That narrow endemism shows up in the conservation tally: alongside a solid core of Least Concern species, the atlas records 8 Endangered and 7 Vulnerable species, consistent with small-range forest stream specialists under pressure from logging and land conversion across the region.