Diagnosis: Haplochromis katunzii belongs to an assemblage of small sized (less than 9 cm standard length), relatively deep-bodied (body depth larger than 35% of standard length) micrognathic species with a moderately curved to straight dorsal head profile; the fish in this group have relatively small, mainly bicuspid, teeth in the oral jaws (Ref. 85523). It can be distinguished from Haplochromis paropius, Haplochromis cinctus and Haplochromis antleter by live colouration of sexually active males: Haplochromis katunzii is sandy-brown, and has rather distinct vertical bars; H. antleter is dusky coloured, has faint vertical bars and no or a faint lachrymal stripe; H. cinctus has a red dorsum, an orange to yellowish flank and dark vertical bars; H. paropius has a red dorsum, a greenish flank and is the only species of the assemblage that often has a mid-lateral band (Ref. 85523). Haplochromis katunzii has a larger cheek depth, 18.6-24.6% of head length, than H. antleter, 16.1-21.1% of head length, as well as a more pronounced mental prominence on the lower jaw; and it has a smaller interorbital width, 19.2-24.1% of head length, than H. cinctus, 24.3-27.2% of head length (Ref. 85523).

Description: Body relatively deep; dorsal head profile straight to moderately curved; premaxillary pedicel not or slightly interrupting the profile (Ref. 85523). Mouth slightly oblique; lips not thickened; medial part of the premaxilla not to slightly expanded; caudal part of maxilla not bullate; the vertical through the caudal tip of the maxilla runs through the iris; lateral snout outline isognathous and obtuse; jaws equal anteriorly; mental prominence not or slightly pronounced; retro-articular processes of right and left mandible may just touch each other, not interrupting the ventral body outline; eye approximately circular; a small aphakic aperture may be present; cephalic lateral line pores generally not enlarged (Ref. 85523). cheek, gill cover, dorsal head surface, greater part of dorsum and caudal fin base covered with cycloid scales; chest mainly with cycloid scales and some weakly ctenoid scales; remaining part of the body with ctenoid scales; a gradual size transition between scales of chest and flank; 4-6.5 scales between the upper lateral line and the dorsal fin origin, 4-6 between the pectoral and the pelvic fin bases (Ref. 85523). Pelvic fins reaching the anal fin origin, in some specimens extending further; first soft rays of pelvic fins often produced and filamentous; anal fin reaching caudal fin origin; caudal fin outline truncate to emarginate (Ref. 85523). The number of gill rakers on the lower part of the first gill arch is 8 to 9; the first raker is reduced, the next one to three rakers are short or normal; the shape of the remaining rakers may be blunt, weakly bifid or trifid; the rakers on the first gill arch may or may not touch each other; the number of gill filaments on the lateral hemibranch of the first gill arch ranges from 89 to 96 (Ref. 85523). Premaxillary dentigerous arm about as long as, or slightly longer than ascending arm; the angle between the two arms is 83° to 89°; sometimes a small symphyseal articulation facet is present; lower jaw slightly elongated; the upper half of the dentary has a moderate to distinct outwardly directed flare; a small mental prominence is present (Ref. 85523). Generally the teeth in the rostral part, ca. 2/3 of dentigerous area, of both premaxilla and lower jaw are unequally bicuspid; sometimes, however, a few unicuspids or tricuspids can be found among them; in the caudal part of the premaxilla, blunt unicuspids, weakly bicuspids or tricuspids can be found; the caudal-most two to three teeth are stout unicuspids or weakly bicuspids; the teeth in the caudal part of the lower jaw are generally tricuspid or subequally bicuspid, sometimes weakly bicuspid or unicuspid; in bicuspid teeth, the shape of the major cusp is isoscelene to subequilateral; a small flange is present, which is moderately distinct in rostral teeth, but hardly visible in more caudally placed teeth; the cusp gap is wide, the minor cusp distinct; tricupsid teeth sometimes may have a slightly protracted middle cusp; in labial view, the neck is moderately slander to stout, the crown slightly expanded; in lateral view, the crown is compressed; the premaxilla outer row teeth are recurved, those of the lower jaw slightly recurved; the inner row teeth of both premaxilla and lower jaw are tricuspid; teeth are relatively small and slender (Ref. 85523). Dental arcade rounded to U-shaped; premaxilla with two to three inner rows anteriorly, none posteriorly; the lower jaw has one to three inner rows anteriorly, none posteriorly; there are 52-67 teeth in the outer row of the upper jaw; premaxillary teeth are closely to widely and regularly set; lower jaw teeth generally closely set, but in a few specimens they are widely and regularly set in the rostral part; outer row teeth of premaxilla erect, inner row teeth recumbent; lower jaw outer row teeth slightly procumbent, inner row teeth erect (Ref. 85523). Lower pharyngeal element relatively slender when compared to that of Haplochromis elegans; as long as it is broad or slightly longer than broad; the dentigerous area is broader than long; the suture is straight; there are 38-42 pharyngeal teeth in the caudal-most transverse riw, 14-15 teeth in the medial rows; teeth in caudal-most transverse row hooked, major cusp only slightly incurved and blunt; other teeth pronounced or bevelled; in general, the teeth are fine and slender, but the medial teeth are sometimes coarser than the other teeth (Ref. 85523). The total number of vertebrae is 28-31, comprising 12-14 abdominal and 16/17 caudal vertebrae (Ref. 85523).

Colouration: Live colouration of males: snout, dorsal head surface, lips, lower jaw and cheek sandy-brown; gill cover, chest and belly varying from light sandy-brown to black with a turquoise sheen; the eye has a dark grey outer ring and a yellowish inner ring; the lachrymal- and supraorbital stripes extend over the iris; dorsum, flank and caudal peduncle sandy-brown, the latter two with a turquoise sheen; rostral part of the ventral side silvery to black, the caudal part sandy-brown to black with a turquoise sheen; nostril-, interorbital- and preopercular vertical stripes, nape band and opercular blotch present; there are four to six vertical bars on the flank; pectoral fins hyaline, pelvic fins black; the rostral part of the anal fin is black, caudal part orange-red gradually changing into hyaline; anal fin with two yolk-yellow to orange, egg dummies surrounded by a dusky ring, in the caudal-most egg dummy the ring is partly hyaline; the caudal fin is orange-red, with a black base; dorsal fin dusky, with, sometimes faint, red maculae; lappets on the rostral half of the dorsal fin are sooty; those on the caudal half are orange-red (Ref. 85523). Preserved colouration of males: entire body yellow-brown; flank, belly, and ventral side dusky; chest yellow-brown to dusky; nostril-, interorbital-, lachrymal-, supraorbital- and preopercular vertical stripes are present; the supraorbital stripe extends into the iris; the nape band is interrupted medially; an opercular blotch is present and ventrally extended; four to six vertical bars on the flank; pectoral fins hyaline, pelvic fins black; generally the rostral part of the anal fin is dusky, caudally only the base of the fin is dusky and the remainder hyaline; egg dummies with a dusky or hyaline ring may be visible; the dorso-rostral part of the caudal fin is often dusky; the dorsal fin is somewhat sooty; the lappets in the rostral part are dusky; in some specimens the base is dusky (Ref. 85523).