Diagnosis: Coptodon nigrans differs from all Tilapia sensu lato, and Coptodon, except for a few members, in quadricuspid to pentacuspid posterior pharyngeal teeth on lower pharyngeal jaw; quadricuspid teeth are known from C. tholloni, C. cameronensis, C. dageti, C. congica, C. deckerti, and partially from C. ejagham (Ref. 85854). It differs from C. cameronensis, C. ismailiaensis and C. dageti in longer lower jaw, 13.9-17.3% of standard length vs. 9.6-13.2%; from C. tholloni in longer snout length, 15.8-18.2% of standard length vs. 11.7-14.6%; from C. congica in lesser body depth, 34.9-40.2% of standard length vs. 41.5-49.2%; and from C. kottae in narrower interorbital width, 10.0-11.8% of standard length vs. 12.4-14.0% (Ref. 85854). Differences to C. deckerti are based on a combination of morphometric, life history, genetic and ecological data, e.g. in longer snout length, 15.8-18.2% vs. 12.7-15.6%, by breeding exclusively in excavated caves below 5 m water depth, vs. always breeding above 2 m; the smallest reproductvely active specimens of C. nigrans are larger than largest reproductively active C. deckerti specimen (Ref. 85854). it differs from C. ejagham in dark square-shaped blotches at base of each flank scale, filled or with a light coloured window at centre of blotch, vs. flank scales with a dark scale margin and a light centre, especially on scales below lateral line (Ref. 85854).

Description: It is a large tilapia with a laterally compressed body; dorsal head profile moderately concave from insertion of first dorsal spine to upper margin of eye henceforward head profile changes to slightly convex (Ref. 85854). Large and compact head; snout outline obtuse; eye moderately large and interorbital width always greater than eye length (Ref. 85854). Greatest body depth at level of first dorsal spine; dorsal line slightly posteroventrally curved; caudal peduncle somewhat longer than deep (Ref. 85854). Body scales cycloid, scales on chest smaller than flank scales and deeply embedded; upper lateral line extending from posterior margin of gill cover to approximately last dorsal ray; upper lateral line separated from first dorsal spine by three to four scale rows; lower lateral line originating at level of first dorsal branched rays and terminates midlaterally on caudal peduncle; one or two scales of lower lateral line extending onto caudal fin; two scale rows between upper and lower lateral line; preoperculum with three to four irregular rows; lower one third of pectoral base mostly lacking scales (Ref. 85854). First ceratobranchial with 8-10 gill rakers and first upper gill-arch with 4-5 gill rakers; ceratobranchial rakers stout, broader on base, pointed; gill raker in angle of arch and first four epibranchial rakers more slender, decreasing in size towards last (Ref. 85854). Origin of dorsal fin at level of origin of pelvic fin; first dorsal spine always shortest, last dorsal spine always longest; longest spines always shorter than longest ray; last dorsal ray most deeply branched; caudal fin outline truncate; third anal spine always longest; tip of longest anal fin ray overlapping hypuralia; last dorsal ray most deeply branched; tip of longest pelvic-fin ray mostly crossing anus (Ref. 85854). Jaws isognathous; teeth in upper and lower outer row in both jaws bicuspid; neck of anterior jaw teeth stout, crown expanded and cusps truncated; one to three incomplete inner rows of smaller tricuspid teeth in both jaws; lower pharyngeal jaw as long as broad, anterior keel shorter than toothed area; posterior pharyngeal teeth quadricuspid to pentacuspid, stout, slightly hooked and regularly arranged, especially over posterior third of toothed area; dentigerous plate triangular; most teeth in the anterior two thirds of toothed area approach the 'kukri' tooth shape (Ref. 85854).

Colouration: Colouration in alcohol: basic colouration brownish; dorsal side dark brownish, ventral side light brownish; dark square-shaped blotches at base of each flank scale, filled or with a light coloured window at centre of blotch, creating the impression of dark network on flanks; lower lip light brownish to whitish, upper lip dark; cheek pale, lower side of head and operculum completely dark; chest blackish and belly light with blackish blotches; seven to eight dark vertical bars on dorsum and sides, first bar at level of first dorsal spine, last two on caudal peduncle, an a nape band; second vertical bar deeply bifurcated; vertical bars sometimes not visible, apparently depending on motivational state by collection; sometimes entire body very dark; no longitudinal mid-lateral band; pectoral fins transparent; pelvic fins blackish; anal fin dark brownish, margins transparent; caudal fin dark brownish and margins transparent with light dots in the upper part; dorsal fin dark brownish, margins transparent; 'tilapia spot' not always visible, however, if present then with two to three dark oblique lines in soft part behind 'tilapia spot' (Ref. 85854). Colouration in life: basic colouration yellow-greenish, breeding grey-greenish, ventral side whitish to reddish, breeding completely black; lower side of head whitish , breeding black, and upper side of head yellow-greenish; upper lip light bluish, lower lip whitish; a horizontal iridescent blue line above antero-rostral margin of preopercle; iris of eyes bright red; body with seven to eight black dark vertical bars, nape band, supraorbital and interorbital stripe; no vertical stripes in breeding colouration; dark opercular spot; in breeding opercular spot mostly not visible, operculum yellow-greenish; pectoral fins transparent, pelvic fins and anal fin with black tips; dorsal fin yellow edged, 'tilapia spot' noticeable; caudal fin completely yellow-greenish (Ref. 85854).