Diagnosis: adipose fin always present; anterior nostrils closer to each other or at same distance as posterior ones; barbels well developed, nasal barbel at least reaching to anterior border of opercle; snout reaching beyond lower jaw, upper lips slightly surrounding lower jaw when mouth is closed; inner side of pectoral spine feebly serrated; striking brownish colour pattern, often irregularly marbled and characterized by the presence of a very dark blotch above pectoral spine, where swim-bladder lies close below skin; eyes rather small (Ref. 43912).

Description: 8-10 branched pectoral fin rays; 35-54 branched anal fin rays; 39-41 non-fused vertebrae; 8-9 branchiostegal rays on one side of head; notable difference in number of branched anal fin rays for populations originating from Middle ZaIre (35-45) and those from Kasai and Kwango Systems (37-54); also a difference in eye diameter between specimens from Kasai-Kwango and specimens from Central Congo Basin, the eye being slightly larger in the former population; posterior side of dorsal spine feebly serrated; caudal peduncle deeper than long; barbels well developed; nasal barbel at least reaching to anterior border of opercle and at maximum to midway along length of pectoral spine; maxillary barbel at least reaching to just beyond opercle and at maximum somewhat beyond end of pectoral spine; inner mandibular barbel rather short and reaches at maximum to posterior border of eye; outer mandibular barbels at least reaching to just beyond base of pectoral spine and at maximum to somewhat beyond midway along this spine; head profile more or less straight; caudal fin-lobes slightly rounded (Ref. 43912). Schilbe yangambianus closely resembles S. brevianalis from Cameroon and Nigeria but in the latter species the nasal barbels are generally considerably shorter (not reaching beyond the anterior border of the opercle); S. yangambianus also resembles the sympatric S. marmoratus, especially by the similar coloration pattern, but both species are easily distinguished by the absence of an adipose fin in S. marmoratus (Ref. 43912).

Coloration: preserved and live specimens: rather large variation in colour pattern; many specimens with head, back, sides and belly irregularly brown marbled; belly and underside of head often speckled with brown; striking dark brown or blackish blotch present above pectoral spine, where swim-bladder lies close below skin; all fins irregularly greyish or brownish, pectoral fins darker than others; pelvic and anal fins often with more or less dark band along base and border, variable in position; caudal fin darker at base (Ref. 43912). Based on Matthes (1964): entirely brownish-purple with black marblings and a distinct, postopercular, round spot, the area between this spot and the ventral fins darker; eye dark brown; fins brown-reddish, with dark brown marbling, pectoral fins dark, pelvic, anal and caudal fins yellowish at base (Ref. 43912).