Diapteron is a genus of small killifish in the family Nothobranchiidae, split out from the larger genus Aphyosemion to hold a distinctive cluster of species from rainforest streams in Gabon and the Republic of the Congo. Unlike the classic annual killifish that live in seasonal pools and survive the dry season as eggs buried in mud, Diapteron is non-annual: it inhabits small, shaded, permanent forest streams and lives across more than one season, closer in life history to typical stream fish than to the drought-adapted killifish of open savanna. At roughly 1.5 in, its species are among the smallest killifish the atlas records.
Diapteron fulgens and Diapteron seegersi are both known for intense, jewel-toned coloration, reds, blues, and iridescent flecking typical of the Aphyosemion group they were split from, which has made the genus a favorite among specialist West and Central African killifish keepers even though it rarely appears in general fish-shop trade. Because these species depend on small, shaded forest streams, they are vulnerable to the kind of localized habitat degradation that logging and land clearing bring to that part of Central Africa, and the elevated IUCN status recorded for the genus in the atlas is consistent with that pressure.