Diagnosis: The presence of supra-pectoral and supra-anal spots, which do not extend to the base of the dorsal fin, plus a precaudal spot and a series of small spots along the base of the dorsal fin, combined with a snout length longer than the postorbital head length distinguishes this species as a member of Stigmatochromis (Ref. 87930). It is further diagnosed by the presence of mostly unicuspid teeth in the outer rows of the lower jaws; Stigmatochromis melanchros is distinguished from S. macrorhynchos by a wider interorbital width, 19.3–20.5% of head length vs. 13.7–16.2%, and from S. pholidophorus by a larger preorbital depth in relation to the vertical eye diameter, 95.8–109.3% vs. 75.4%; it is distinguished from S. modestus by a shorter lower jaw, 40.7–44.4% of head length vs. 45.2–48.3%, and by fewer teeth in the outer row of the left lower jaw, 13–19 vs. 24–28; it has a smaller horizontal eye diameter, 25.2–26.9% of head length, than S. woodi, 27.0–32.6% (Ref. 87930).

Description: Jaws prognathous; teeth on jaws in 3-4 rows; teeth in outer row unicuspid; teeth in outer row of left lower jaw 13-19 (Ref. 87930). Scale rows on cheek 3; lateral-line scales 31-32; pored scales posterior to hypural plate 2-3 (Ref. 87930). Gill rakers on first ceratobranchial 9-12, with 3-5 on epibranchial (Ref. 87930).

Colouration: Males with anterior portion of head dark gray and posterior portion light gray/silver with green highlights; laterally, dark blue/black with scales outlined in blue/green; dorsal fin dark gray with blue/green highlights and orange and white tips; caudal fin dark gray with blue/white markings; anal fin black with pale yellow/white ocelli; pelvic fins black with white leading edge; pectoral fins with gray rays and clear membranes (Ref. 87930). Females with gray interorbital and gray/white cheeks and operculum; laterally, silver with pale orange outline of scales; three lateral spots and a series of black markings along base of dorsal fin; dorsal fin clear with faint orange markings; caudal fin clear with gray markings in membranes; anal fin clear with several yellow ocelli; pelvic fin clear with white leading edge; pectoral fin clear (Ref. 87930).