Diagnosis: A heavily-built large tilapia species with a wide rounded head and short jaws; individuals vary a lot in dentition, with some having very wide bands of jaw teeth (Ref. 118638). Head length 30.8-36.0% of standard length; lower pharyngeal with large toothed area with straight or slightly convex sides; median length of pharyngeal bone 1.14-1.32 times its width and 38.2-42.2% of head length; blade 1.0-1.7 times median length of toothed area; length of lower jaw 28.4-34.5% of head length; teeth of jaws in 4-6 rows (Ref. 2). Females and juveniles with greyish-brown bodies and 4-5 vertical bars (Ref. 118638). Males are black with a white margin to the dorsal and tailfins; the genital tassel can be long and branched and pinkish to bright yellow (Ref. 2, 118638). It is one of the 'chambo' group Oreochromis from the Lake Malawi catchment; females and non-territorial males cannot be reliably distinguished from those of Oreochromis squamipinnis; females and non-territorial males from Lake Ikapu are a bright golden colour (Ref. 118638).

Description: Upper profile of snout before eye usually convex (Ref. 55427). Jaws small (Ref. 6150). Tooth band wide (Ref. 4967). Lower pharyngeal bone heavily developed; size of head and jaws, depth of body and number of tooth rows population dependent (Ref. 55079). Sides of triangular toothed area of lower pharyngeal bone not concave (Ref. 55427). Caudal fin scaly (Ref. 2, 55427) and emarginate (Ref. 2). In adults both upper and lower lobes of caudal fin rounded; caudal peduncle as long as or longer than deep; genital papilla prominent and bifid in breeding fishes (Ref. 2). Males develop a breeding dress (Ref. 5595) and a genital tassel (Ref. 5595, 44514), each branch bearing tubercles and filaments (Ref. 2).

Colouration: Non-breeding fish: silver-grey, darker on the dorsum, with black vertical bars of uneven length from the dorsum to mid-flanks (Ref. 2). Ripe females: very dark, almost black (Ref. 55079). At some times of the year (Ref. 55079) females, juveniles and non-breeding fish develop a yellowish-brown body with yellow margin to the dorsal fin (Ref. 6150, 55079). Courting male: black (Ref. 2781, 4967, 6150, 55079), often with iridescent patches on the head or body (Ref. 55079). Flank scales often with coppery metallic spot (Ref. 55079). Broad white margins to dorsal (Ref. 2, 55427) and caudal fin and sometimes also to the anal fin (Ref. 2). Black color lost in a few seconds when alarmed, turning a pale grey, often with iridescent greenish or coppery areas on the flanks or head (Ref. 40193).