Diagnosis: 'Barbus' devosi belongs to the 'B.' eutaenia / 'B.' miolepis species-complex, because of its ossified and serrated last unbranched dorsal-fin ray and a live colour pattern including orange fins and a black mid-lateral stripe (Ref. 92865). It differs from the allopatric members of the complex by the following unique combination of characters: more gill rakers on the ceratobranchial of the first gill arch, 6-9 vs. 2-5 for 'B.' eutaenia and 'B.' miolepis; shorter anterior barbel, 11-19% of head length vs. 20-35% for 'B.' eutaenia and 20-37% for 'B.' miolepis; shorter posterior barbel, 15-27% of head length vs. 22-44% for 'B.' eutaenia and 27-46% for 'B.' miolepis; and the absence of a sheath of enlarged, prominent scales at the base of the dorsal fin as found in 'B.' eutaenia and 'B.' miolepis (Ref. 92865). 'Barbus' devosi differs from 'B.' choloensis by; fewer circumpeduncular scales, 10-12 vs. 14-16; fewer lateral line scales, 24-27 vs. 28-30; fewer scales between the lateral line and the anterior origin of the dorsal fin, 4,5 vs. 5-6; and it is a small to medium sized species, while 'B.' choloensis attains up to 200m standard length (Ref. 92865). 'Barbus' devosi differs from 'B.' seymouri by: more gill rakers on the ceratobranchial of the first gill arch, 6-9 vs. 4; its relatively shorter barbels, anterior barbel 31-64% of eye diameter vs. 46-96%, posterior barbel 46-87% of eye diameter vs. 71-123%; and fewer lateral line scales, 24-27 vs. 26-29 (Ref. 92865). Within the Lake Tanganyika drainage system 'B.' devosi is distinguished from all other small 'Barbus' by the following unique combination of characters: presence of a bony, serrated, last unbranched dorsal-fin ray; a complete lateral line; 24-27 lateral line scales; a permanent black mid-lateral stripe; and two pairs of barbels (Ref. 92865).
Colour: Dorsal and dorso-lateral parts of body and head dark brownish; flank grey silvery and ventral part whitish; a black mid-lateral stripe extending from tip of snout across eye and operculum to base of caudal fin and, in some specimens, onto mid-caudal fin rays, marking division between upper and lower lobes; mid-lateral stripe bordered dorsally and sometimes ventrally by a golden yellowish of whitish streak (Ref. 92865). Scales above lateral line darker at their edges (Ref. 92865). Dorsal and caudal fins grey-yellowish to grey-whitish with pinkish-orange tips; small specimens with more extended pinkish-orange colour on caudal and dorsal fins; pectoral fin grey yellowish to whitish, pelvic and anal fins translucent (Ref. 92865). Barbels with silvery grey base and whitish tip (Ref. 92865). Dorsal parts of preserved specimens dark brown; flank and belly grey to grey-yellowish; mid-lateral stripe dark brown or brown, less pronounced on snout in some specimens; barbels with dark base and yellowish tip; fins whitish and translucent; scales with darker edges visible in some specimens (Ref. 92865).