Diagnosis: Afronemacheilus abyssinicus is distinguished from its congener A. kaffa by having usually 8 or 9 branched dorsal-fin rays (vs. usually 7); the anterior and posterior nares closely spaced (vs. well separated); the intestine straight (vs. with a single small loop), no contact between sphenotic and epiotic (vs. usually in contact); two pairs of pharyngobranchials and usually three basibranchials (vs. three and four, respectively); the dark spots on flank small and irregular becoming larger and transversely extended on dorsum (Ref. 94278).

Description: Posterior naris situated immediately behind anterior one, or separated by less than half-diameter of posterior naris (Ref. 94278). Anterior maxillary barbel reaching base of mandibulary barbel or slightly beyond; posterior maxillary barbel reaching to, or slightly behind, vertical through anterior margin of orbit; mandibulary barbel reaching to or slightly beyond posterior border of orbit (Ref. 94278). Lips nearly smooth or only slightly crenulated; upper lip continuous or weakly incised in middle; lower lip interrupted and bearing rather short but pronounced mental lobes and one or two more or less deep grooves on each medial pad; dentiform process strong, matched by a corresponding incision on lower jaw (Ref. 94278). Head sensory pores very small; supraorbital canal with 7 pores, continuous or interrupted and composed of nasal and supraorbital portions, latter sometimes also interrupted; supraorbital and infraorbital canals not connected; infraorbital canal with 11-14 pores; preoperculo-mandibular canal with 8-9 pores, uppermost pore at horizontal line through mouth corner; supratemporal canal continuous or interrupted (Ref. 94278). Dorsal fin with 3-5 unbranched and 8-9 branched rays; dorsal-fin origin slightly closer to caudal-fin base than to tip of snout; dorsal-fin distal margin always distinctly convex because 2nd to 4th branched rays are longer than others; anal fin with 3-4 unbranched and 6-8 branched rays; distal margin of anal fin convex; pectoral fin with 1 unbranched and 10-12 branched rays; pelvic fin with 1 unbranched and 6-8 branched rays (Ref. 94278). Caudal-peduncle length/depth ratio 1.3-2.0 (Ref. 94278). Body entirely scaled; scales rather close to each other on most parts of the body, but not imbricate; scales on flanks below dorsal fin slightly deeper than long, with large focal zone (Ref. 94278). Vertebrae 4+35 to 4+37 (Ref. 94278).

Colouration: Background very light, yellowish or creamy, overlayed with dense brown spotted pattern (Ref. 94278). Rather large and transversally broadened blotches on dorsum, 7-13 in number, from occiput to caudal-fin origin; these blotches usually expanded to dorso-lateral part of body, but before dorsal fin frequently becoming smaller, roundish, distributed irregularly or in staggered rows, and not expanded to dorso-lateral part of body; row of small blotches irregular in form along midlateral line; these blotches smaller in depth than distance from midline to dorsal outline, but less frequently these almost as deep as entire body depth; gaps between these lateral blotches equal to or larger than longitudinal dimensions of blotches themselves; dorsal blotches sometimes fused with lateral blotches, especially, behind dorsal fin (Ref. 94278). In addition to large blotches, flank speckled with small irregular spots and solitary melanophores, latter frequently producing a thin irregular line along mid-lateral septum; ventro-lateral surface of head and body before anal-fin origin light and not speckled, but becoming speckled caudally; one to three large spots sometimes present on ventral outline of caudal peduncle; dorsal and lateral parts of head densely speckled (Ref. 94278). Base of caudal fin with 0-4 rounded marks organized into vertical row; dorsal and caudal fins with pigment on membrane and rays; condensed in dark marks organized in more or less regular rows, much more pronounced on caudal fin; other fins transparent (Ref. 94278).