Petrocephalus christyi is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics: dorsal fin with 22-24 branched rays, anal fin with 25-29 branched rays, eye large (HL/ED=3,1-4,2), mouth small, 9-13 teeth in the upper jaw, 17-22 teeth in the lower jaw (Ref. 85331). Melanin pattern consisting of two characteristic black patches: (1) a distinct round mark below the anterior base (first to the fifth rays) of the dorsal fin; and (2) a somewhat diffuse crescent-like mark, centered at the base of the caudal fin and extending onto the fleshy dorsal and ventral lobes of this fin (Ref. 85331).