Crenichthys is a genus of springfish in family Goodeidae, restricted to isolated desert spring systems in Nevada, United States. The atlas covers 2 species, 2.5–3.5 in: C. baileyi, the White River springfish, and C. nevadae, the Railroad Valley springfish. Like their better-known Mexican goodeid relatives, the splitfins, Crenichthys are livebearers rather than egg-layers - an unusual trait among the desert-spring fish community, which is otherwise dominated by egg-laying pupfish.
These are classic Great Basin relict species, each confined to a handful of isolated warm springs after the region's ancient lake systems dried and fragmented over thousands of years. That extreme habitat narrowness makes them genuinely precarious - the atlas records one species Endangered and the other Vulnerable, and the genus carries a CARES conservation priority listing here. Groundwater pumping, spring modification, and introduced species are the ongoing threats to what water they have left. Aquarium interest centers on conservation-minded desert-fish and goodeid specialists rather than the general trade, given how narrow and fragile the wild range is.