Diagnosis: Species with a piscivorous morphology; premaxillary pedicel and mental prominences strongly developed; outer oral teeth few and large, 22-31; dominant males yellow with an orange anterior part of flank (Ref. 126312). Amongst piscivorous species from the Lake Edward system, Haplochromis simba differs from H. latifrons, H. mentatus, and H. glaucus by the combination of a narrower interorbital area, interorbital width 45.5-50.4% of head width vs. 50.9-63.3%; and a strongly developed vs. absent or weakly developed mental prominence; it further differs from H. latifrons by a longer anal fin base, 17.3-19.0% of standard length vs. 14.7-17.3%; and absence vs. presence of a well-defined mid-lateral band; further from H. mentatus by a smaller number of outer upper jaw teeth, 22-31 vs. 28-46; and dominant males yellow with an orange anterior part of flank vs. green-yellow with a red anterior part of flank; further from H. glaucus by a narrower lower pharyngeal element, lower pharyngeal width 83.8-87.9% of lower pharyngeal length vs. 93.3-95.1%; and dominant males yellow with an orange anterior part of flank vs. uniformly light-blue (Ref. 126312). It differs from H. rex and H. aquila by the combination of a smaller number of scales between first anal-fin spine and upper lateral line, 9-11 vs. 12-16, rarely 11; and a strongly developed vs. absent or weakly developed mental prominence; it further differs from H. rex by a lower number of longitudinal line scales, 32-33 vs. 34-38; and dominant males uniformly yellow with an orange anterior part of flank vs. cream-coloured with an orange operculum and a light blue snout; further from H. aquila by a smaller eye, eye diameter 26.7-29.5% of head length vs. 30.0-31.5%; and dominant males yellow with an orange anterior part of flank and a yellow head vs. uniformly light grey with a black head (Ref. 126312). It differs from H. kimondo, H. falcatus, H. curvidens, H. pardus, H. quasimodo, and H. squamipinnis by the combination of large vs. small outer oral teeth and a smaller number of outer upper jaw teeth, 22-31 vs. 39-79; it further differs from H. falcatus, H. curvidens, and H. pardus by a deeper lacrimal, lacrimal depth 18.7-20.5% of head length vs. 16.0-18.8%; further from H. kimondo and H. quasimodo by a narrower head, head width 39.5-41.5% of head length vs. 42.0-48.1%; further from H. squamipinnis by absence vs. presence of minute scales on proximal part of dorsal fin (Ref. 126312).

Description: Body shallow and oval to slightly pyriform; caudal peduncle shallow (Ref. 126312). Head long, narrow, and with a straight to weakly convex dorsal outline and a weak concavity above eye; eye small and high on head; interorbital area narrow; cheek and lacrimal deep (Ref. 126312). Snout long, rounded in dorsal outline, acute in lateral view, and slopes gently at 30-45°; premaxillary pedicel average in length and strongly prominent; jaws isognathous to prognathous, long, slim, very narrow, and rounded in dorsal view; gape large and slopes gently at 20-25°; maxilla extends to between verticals through anterior point of orbit and just past this point; lower jaw relatively shallow and with a straight ventral outline in lateral view, mental prominence strongly developed, and lower jaw side steep with an inclination of 35-40° to horizontal in anterior view; upper jaw expanded anteriorly and ventrally; lips and oral mucosa thin (Ref. 126312). Neurocranium shallow, ethmo-vomerine block decurved, preorbital region very shallow, 18-20% of neurocranium length, orbital region shallow, 26-28% of neurocranium length, and supraoccipital crest shallow and wedge-shaped (Ref. 126312). Outer oral teeth few, unicuspid, and very large; necks stout, conical, and straight; crowns straight to weakly recurved, and acutely pointed; dental arcades rounded; outer teeth widely and irregularly set with neck-distances of 1-4 neck-widths; in upper jaw, 1-2 posteriormost teeth enlarged; inner teeth small, recurved, unicuspid, and acutely pointed; tooth bands very slender crescent-shaped with 1-2 rows of inner teeth, and narrow posteriorly until outer row remains past 2/3 length of tooth band; inner teeth widely and irregularly set on 1-2 outer tooth neck-widths from outer row; implantation erect in first row and recumbent in subsequent rows; in upper jaw, size decreases slightly buccally and posteriorly (Ref. 126312). Lower pharyngeal bone long, very narrow, slim, and shallow over whole length; pharyngeal teeth relatively large and slender; major cusps acutely pointed; cusp gaps concave; minor cusps and cusp protuberances very small; teeth in two median longitudinal rows equal in size and form to lateral teeth, 12 in each row; posterior transverse row with 16-18 teeth, implanted recumbently with a lateral inclination; major cusps weakly recurved, bluntly pointed, and laterally compressed; minor cusps mostly absent (Ref. 126312). Chest scales small; transition to larger flank scales gradual; minute scales on proximal half of caudal fin; scales on longitudinal line 32-33, scales on upper lateral line 19-22, scales on lower lateral line 8-10, scales between dorsal fin and upper lateral line 5-6, scales between upper lataeral line and anal fin 9-11, scales around caudal peduncle 16-19, scales between pectoral and pelvic fins 5-7, infraorbital cheek scales 4-5, postorbital cheek scales 9-12 (Ref. 126312). Caudal fin emarginate; dorsal and anal fins reach to between verticals through two scales anterior to and one scale posterior to caudal-fin base; pectoral fin reaches to between anal opening and second anal-fin spine; pelvic fin reaches to between first and second anal-fin spines; first branched pelvic-fin ray elongated (Ref. 126312). Ceratobranchial gill rakers in outer row of first gill arch short, stout, and simple; posteriormost rakers anvil-shaped to weakly bifid; epibranchial gill rakers slender and simple (Ref. 126312).

Colouration: Colouration in life of dominant males: body yellow; operculum, cheek, and anterior part of flank orange; belly and chest white; snout dusky; lower jaw and lips pink; eye with (dark) grey outer ring and silver to golden inner ring; nostril and lacrimal stripes faint; mental blotch present; pectoral fin yellow; pelvic fin black; dorsal fin hyaline to dusky and with black lappets and a dusky posterior part; anal fin faint crimson and with 2-3 very large orange egg-spots with hyaline rings; caudal fin dusky and with a faint crimson ventral part and a maculated dorsal part (Ref. 126312). Non-domninant males: anterior part of flank, operculum, and cheek with pink sheen; anal fin with crimson anterior part and hyaline posterior part; caudal fin uniformly dusky (Ref. 126312). Colouration in life of females and juveniles: body, operculum, and cheek yellow; belly and chest white; lacrimal and lower jaw pink; snout dusky; eye with (dark) grey outer ring and silver to golden inner ring; nostril and interorbital stripes faint; mental blotch present; pectoral, anal, and caudal fins yellow; anal fin with a white base; caudal fin with a dusky base; dorsal fin hyaline and with black lappets and a dusky distal part (Ref. 126312). Preserved colouration: Body whitish; dorsum and cheek brown; belly, chest, and operculum white; snout dusky; nostril stripe well-defined; lacrimal stripe and mental blotch present; interorbital stripe and nape band faint; pectoral fin dusky; pelvic fin yellowish in females black in males; dorsal fin dusky and with black lappets and sooty posterior part; anal fin yellowish and with 1-2 large egg-spots; caudal fin dusky and with a maculated dorsal part (Ref. 126312).