Aphaniops is a genus of small killifish-like toothcarps, closely related to (and until recently often included within) Aphanius, and placed in the pupfish family Cyprinodontidae. The atlas's 7 species are found across arid parts of the Middle East and the Horn of Africa, with records from Iran, Oman, Ethiopia, Iraq, Israel, Saudi Arabia, Bahrain, and Egypt — a range built from isolated desert springs, wadis, coastal lagoons, and a few enclosed inland lakes. Sizes run small, from about 1.5 in up to 3 in, and like other pupfish relatives the genus favors extreme, patchy habitats: hypersaline pools, spring outflows, and brackish or thermal water where few other fish can survive.
Because so many species are confined to a single spring system or lake, Aphaniops is more a conservation and biogeography story than an aquarium mainstay. Aphaniops richardsoni (Dead Sea killifish) and A. stiassnyae (Lake Afdera killifish) are extreme examples, tied to a shrinking hypersaline sea and an Ethiopian soda lake respectively, and the atlas records one species as Endangered against a background of mostly Not Evaluated status — reflecting how poorly studied much of the genus still is rather than a clean bill of health. Two species carry CARES status here, underscoring that isolated desert-spring endemics like these are exactly the kind of narrow-range fish conservation breeding programs exist for. A. dispar and A. stoliczkanus, both known as Arabian killifish, are the most wide-ranging members and the ones most likely to turn up outside pure hobbyist specialty circles.