Diagnosis: A large, deep-bodied species with 4, rarely 3 or 5, anal fin spines (Ref. 118638). Females and immatures from the Lake Malawi catchment have a dark olive-coloured body, yellow-gold below; other populations, such as those from Lakes Chilwa and Chiuta and the Ruvuma system show a more silvery colour; unusually for Oreochromis, the horizontal stripes are often more prominent than the vertical bars; adult males develop very large jaws and a concave head profile, they are black, with red margins to the dorsal and caudal fins (Ref. 118638). Underwater or in aquaria, males show numerous white spots on the upper half of the flanks, but these fade quickly under stress, so that they appear uniformly black when removed from the water (Ref. 118638).

Description: Jaws enlarged in big mature males, but outer teeth mostly remaining bicuspid (Ref. 2). Length of pharyngeal bone from a little less to a little more than its width; blade 0.8-1.26 length of toothed area; teeth slender and firm (Ref. 2). Usually IV anal spines, rarely III or V; caudal fin scaly, but less densely than in the Oreochromis squamipinnis group (Ref. 2). Scales in lateral line series 31-33; 3.5-4 between origin of dorsal and lateral line, 4-7 between bases of pectoral and pelvic fins; in 2-3 rows on the cheek (Ref. 2). Lower gill rakers 16-21, usually 17-19 (Ref. 2). Vertebrae 29-30 (Ref. 2). Genital papilla of male simple (Ref. 2).

Colouration: Breeding male becoming very dark to black, but not with white lower parts of head (Ref. 2).