Diagnosis: Distichodus mbiniensis is readily distinguished from the larger-bodied, higher-scale count Distichodus species (D. antonii, D. atroventralis, D. fasciolatus, D. lusosso, D. mossambicus, D. sexfasciatus, D. langi, D. rostratus, D. engycephalus, D. kasaiensis, D. ingae, D. polli, D. petersii, D. nefasch, D. brevipinnis and D. schenga) in having fewer lateral line scales, 40-42 vs. more than 60, and in achieving a smaller maximum standard length, less than 15 cm vs. more than 30 cm (Ref. 127217). This species is also distinguished from the smaller-bodied, lower-scale count Distichodus species in the following ways: Distichodus mbiniensis is distinguished from D. decemmaculatus and D. teugelsi in having two rows of teeth on the lower jaw vs. one; it can be readily distinguished from D. noboli, D. hypostomatus and D. maculatus in having fewer scales along the lateral line, 40-42 vs. 45, 53-60 and 75 respectively, and distinguished from D. rufigiensis in not having prominent vertical bars along the sides; it is distinguished from D. kolleri in having fewer dorsal-fin rays, 16-18 total vs. 21-26, and distinguished from D. altus and D. affinis in having fewer total anal-fin rays, 13-14 vs. 21-22 (Ref. 127217). Distichodus mbiniensis is distinguished from D. notospilus in having more scales along the lateral line, 41-42, rarely 40, vs. 37-39, rarely 40, a much less prominent elongated dark spot at the base of the caudal fin, a shorter dorsal fin, 21.4-27.2% of standard length vs. 22.7-34.2%, and shallower caudal peduncle, 11.8-13.0% of standard length vs. 12.3-14.1%; it is distinguished from D. microps in having a deeper body, usually seven scales from lateral line to the pelvic fin vs. six, a subterminal mouth vs. the nearly inferior mouth of D. microps, a shallower, 11.8-13.0% of standard length vs. 12.4-14.2%, and shorter caudal peduncle, 9.7-12.6% of standard length vs. 11.9-14.8%, a larger eye, 58.6-88.0% of snout length vs. 56.7-80.4%, a wider subopercle, and a shallower infraorbital 1 with a more curved anterolateral margin vs. a deeper infraorbital 1 with a more rectangular anterolateral margin in D. microps (Ref. 127217).

Description: Body laterally compressed and moderately elongate; dorsal profile with a convex curve from tip of snout to the vertical of anterior margin of eye, weakly concave from the vertical of the eye to posterior margin of head, and convex to origin of dorsal fin; profile weakly convex from origin of dorsal to adipose fin origin; weakly concave from adipose fin origin to caudal fin; ventral profile broadly convex from snout to origin of anal fin; weakly concave from anal-fin terminus to caudal fin; body covered in relatively large ctenoid scales; extending over the proximal half of adipose fin and caudal fin (Ref. 127217). Mouth subterminal; two rows of bicuspid teeth in the upper and lower jaws (Ref. 127217). Dorsal fin with convex margin; its origin just anterior to the vertical of the origin of the pelvic fins; adipose fin two thirds the distance from dorsal-fin terminus to caudal fin origin; base entirely anterior to the vertical of anal-fin terminus; distal tip extending beyond vertical of anal-fin terminus; caudal fin forked; upper and lower lobes slightly rounded with moderate point; anal fin with concave margin; base nearly equal to longest ray; pelvic-fin origin at mid-length of snout to caudal fin distance; nearly as long as head length; pectoral-fin origin just posterior to vertical of posterior margin of subopercle; horizontal just inferior to inferior margin of subopercle; slightly longer than pelvic fin (Ref. 127217).

Colouration: Live colouration: in both large and small specimens the ground colour is bronze with some yellow and gold along the sides of the head; some dark melanophores on subopercle in larger specimens which appears to be absent in smaller specimens; anal and pelvic fins bright red in smaller specimens, a darker brick-red in larger individuals; pectoral fins, adipose fin, and caudal fin clear to yellow; the dorsal fin with prominent black spot originating at the base of the third or fourth ray and extending anteriorly at an angle to the first ray; in small specimens this black marking extends to the distal tip of the dorsal fin but only extends distally about two-thirds in larger individuals; the last third of the dorsal fin is clear to yellow in smaller specimens and a darker red to yellow in larger specimens (Ref. 127217). Colouration after preservation: specimens are medium to dark brown along the back and upper quarter of sides, lighter below; scales along sides have darker spot on anterior and posterior margin providing an effect of light horizontal stripes; pigmentation on opercle and subopercle, and the spot at base of caudal fin more distinct than in live specimens; fins beige with the dorsal fin with distinct black marking (Ref. 127217).