The dark-edged splitfin (Girardinichthys multiradiatus) is a species of fish in the Goodeidae family endemic to Mexico. It is a live-bearing, cold-water fish from the mountains of Mexico. The species is incredibly temperature sensitive. If water is too cold, all offspring turn out to be male. If water is too hot, females will birth their first brood of only 1–3 fry and then die shortly thereafter, which makes it very difficult to maintain a colony. It is also a primarily herbivorous species and requires a great deal of vegetable matter in its diet.