The butterfly splitfin or butterfly goodeid, Ameca splendens, is a bony fish from the monotypic genus Amecaof the splitfin family (Goodeidae). It was formerly found throughout the Ameca River drainage in Mexico; the type locality is Rio Teuchitlán in the vicinity of Teuchitlán, Jalisco. The species was only ever found in an area about 10 miles (15 km) in diameter.