Diagnosis: Nothobranchius mkuziensis can be distinguished from Nothobranchius orthonotus by a lesser body depth, lower number of scales on the mid-longitudinal series, 24-25 vs. 28-30, lower number of transverse scales, 9 vs. 11-12, and a different colour pattern of the unpaired fins, wide bars vs. small spots (Ref. 59344).

Description: Dorsal fin with iii,13 rays, longest median rays reach beyond caudal base; anal fin with iii,12 rays (Ref. 119752). Scales 24-25 in median lateral series to caudal base and 3-4 more on latter; 9 transversely, 18 predorsal, 3 rows on cheek; scales with 17 basal parallel short marginal striae; circuli coarse, complete (Ref. 119752).

Colouration: Back dull olive, belly and under-surfaces paler to whitish; iris gray; paired fins and caudal pale olivaceous, latter with some dark gray medially; dorsal and anal gray, spotted with darker or dusky gray, forming more or less oblique bands (Ref. 59344, 119752).