Heros liberifer can be diagnosed from all its congeners by having the following characters: a pattern of several horizontal series of bright red dots on the lower half of the body sides (vs. absence of rows of red dots); distinct caudal spot in adult specimens (vs. caudal spot usually merged with bar 2 in adult specimens); and tiny dark dots on operculum and cheeks in adult males (vs. large dots or a vermicular pattern). It differs from adult specimens of the frequently syntopic Heros severus by narrow (vs. thick) lips, bar 4, which is not shortened, but extends from the anal fi n base onto the base of the dorsal fin (vs. bar 4 extending only slightly above the lower lateral line), by the first two anterior hemal spines, which are broader and partially connected (vs. the first three hemal spines connected), and a bright red (vs. brown to dark reddish) iris in live specimens (Ref. 114589).