Diagnosis: Haplochromis taurinus differs from all Haplochromis species of Lake Edward system by its anteriorly curved outer teeth in the lower jaw (Ref. 127594). It is distinct from all other known paedophagous species within these lakes by its larger eyes, 32.9-40.2% of head length vs. 29.0-34.7%, and outer teeth with conical necks and bicuspid crowns with major cusps that bear a clear flange vs. cylindrical to constricted necks and uni-, bi-, or weakly tricuspid crowns that, in large specimens of more than 100 mm standard length, bear no flange (Ref. 127594). It is similar to H. molossus and H. gracilifur by its rounded jaws and small lachrymal bones; distinct from H. gracilifur by its deeper caudal peduncle, depth 73.9-88.1% of caudal peduncle length vs. 62.9-66.4%, and longer premaxillary pedicel, 23.5-26.2% of head length vs. 18.1-21.6%; distinct from H. molossus by its more slender jaws, 51.4-72.7% of lower jaw length vs. 67.0-87.0%, more gentle sloping snout, 35-40° vs. 45-55°, and steeper gape inclination, 40-45° vs. 20-30° (Ref. 127594). It is easily separated from H. relictidens and H. paradoxus by its smaller lachrymal bones, 11.5-16.4% of head length vs. 15.8-18.4% and 14.7-21.5%, respectively, and broadly rounded lower jaw vs. anteriorly slender lower jaw; in addition, it has more outer teeth in the upper jaw than H. relictidens and fewer than H. paradoxus, 23-39 vs. 16-26 and 36-65, respectively (Ref. 127594). Mature males of H. taurinus have metallic-blue bodies with dark red flanks vs. colour pattern different in all other paedophagous species (Ref. 127594).

Description: Eyes large, head short, snout concave, and slopes at 35-40°; jaws iso- to prognathous, long, and broadly rounded; gape inclination 40-45°; maxillae bullate, posteriorly enlarged and exposed, reaching posteriorly to vertical through anterior margin of pupil; lips and oral mucosa firmly thickened (Ref. 127594). Neurocranium of generalised or nearly generalised Haplochromis type; supraoccipital crest high and pyramidical (Ref. 127594). Flank scales ctenoid; chest scales smaller than flank scales, size transition gradual; scales in longitudinal series 31-33, upper lateral line scales 19-22, lower lateral line scales 9-13, scales between dorsal fin and upper lateral line 5-6, scales between upper lateral line and anal fin 9-11, scales between pectoral fin and pelvic fin 5-7, cheek scales 2-4/7-9 (Ref. 127594). Outer oral teeth small, stout, and bicuspid; rarely, some uni- or tricuspid teeth laterally and posteriorly in outer rows; necks cylindrical to conical, and with straight implantations; major cusps subequilateral, bluntly pointed, and with a clear flange, i.e. a thin and flat protrusion, laterally implanted on cusp; minor cusps stout and slightly horizontally inclined; in upper jaw, necks slightly recurved and posteriormost teeth tricuspid; in lower jaw, necks straight and both major and minor cusps often anteriorly curved; tooth bands in both jaws broadly rounded and short, i.e. posterior thirds of premaxillae bear no teeth; dental arcades narrow with 1-3, mostly 2, rows of small and tricuspid inner teeth; one outer tooth with spacing between inner and outer rows; number of inner tooth rows quickly diminish posteriorly, until only outer row remains; teeth in all rows closely and consistently set, bases of outer teeth almost touching each other; necks of all teeth deeply embedded in oral mucosa; in lower jaw, crowns of all teeth mostly visible and lower lip uniformly thickened but not dorsally enlarged; hence lip reaches same height as oral mucosa; anterior part of upper lip thin and crowns visible; laterally, upper lip quickly thickens and covers teeth completely (Ref. 127594). Lower pharyngeal bone 1.1 times longer than broad and shallow; keel narrows anteriorly in lateral view, giving it an acute outline; pharyngeal teeth with straight and cylindrical necks and bicuspid crowns; major cusps straight and pointed with blunt tips, cusp gaps slightly concave, and minor cusps very small; teeth posteriorly in two median rows slightly stouter; posterior edge of bone set with 23-27 stout and bluntly pointed teeth with slightly hooked major cusps and reduced minor cusps (Ref. 127594). Ceratobranchial gill rakers on outer row of first gill arch unifid, short, and pointed anteriorly, becoming longer, blunt, and in some specimens bi- to quadrifid posteriorly; epibranchial gill rakers unifid, slender, and pointed (Ref. 127594). Caudal fin emarginate; dorsal and anal fins almost reach caudal fin base in females, extend to between caudal fin base and first quarter of caudal fin in males; pelvic fins extend to between anus and second spine of anal fin in females, up to second branched ray of anal fin in males; pectoral fins extend to between genital opening and second spine of anal fin in both sexes (Ref. 127594).

Colouration: Live colour pattern of mature males: body with a metallic shine; dorsum, dorsal part of caudal peduncle, snout, and chest blue; belly, posterior part of flanks, and ventral half of caudal peduncle gold-yellow; opercula and anterior part of flanks dark red; lachrymal stripes and a mental blotch present, while vertical preopercular, nostril, and interorbital stripes only faintly visible; pectoral fins hyaline to dusky, pelvic fins black, and dorsal and anal fins grey-blue; anal fin with 3-7 orange-brown small egg spots, size equal to distance between adjacent fin rays; branched rays of dorsal and caudal fins often weakly maculated, i.e. dotted lines on membranes between fin rays (Ref. 127594). Live colour pattern of females and juveniles: dorsum blue-green, flanks yellow-green, and belly white; caudal fin yellowish, pectoral fins yellow-green, and dorsal, pelvic, and anal fins hyaline to yellow; anal fin with vague, orange spots that resemble egg spots; lips yellow-green and a mental blotch and faint nostril, interorbital, and lachrymal stripes present (Ref. 127594). Preserved colour pattern in alcohol: body grey-brownish, dorsally darker; belly whitish in females and juveniles, blackish in mature males; a mental blotch, vertical preopercular, and lachrymal stripes present; interorbital and nostril stripes and a nape band faintly visible; posterior part of dorsal fin and upper part of caudal fin often weakly maculated; anal fin of mature males with 3-7 faint egg spots (Ref. 127594).