Relief map of Nicaragua showing the relevant lakes. Crater lake Apoyeque is located beside the great Lake Managua and the crater Lake Xiloá, in western Nicaragua, Central America. Two morphs of Midas cichlid are found in Apoyeque: one with fleshy lips (upper individual; 'thick-lipped') and the other with thin, normal A. citrinellus lips (lower individual; 'thin-lipped').
Elmer et al. BMC Biology 2010 8:60 doi:10.1186/1741-7007-8-60