Skiffia is a genus of livebearing fish in family Goodeidae, the Mexican livebearers, endemic to the central Mexican highlands. Like other goodeids, males lack the true gonopodium seen in mollies and guppies; instead a modified section of the anal fin (the andropodium) delivers sperm, and developing embryos are nourished inside the ovary via trophotaeniae - ribbon-like, placenta-analogous structures unique to this family, rather than by a yolk sac alone.
The genus carries one of the atlas's starkest conservation stories. The golden skiffia (S. francesae) is Extinct in the Wild, surviving only through captive breeding after its native habitat was degraded by water extraction and the introduction of non-native fish. The olive skiffia (S. lermae) and spotted skiffia (S. multipunctata) are both Endangered, matching the brief's tally of 1 Extinct-in-the-Wild and 2 Endangered. All three atlas species carry CARES priority status, and Skiffia is a focal genus for the small international network of hobbyist and institutional goodeid keepers working to maintain genetically viable populations of central Mexico's most imperiled livebearers as insurance against extinction.