Diagnosis: Epiplatys atratus belongs to a supragroup of species, the E. multifasciatus, ansorgii and sangmelinensis species groups, characterized by the possession of a large mouth, reaching the ventral border of the eye (Ref. 94049). It is placed in the E. multifasciatus species group and distinguished from members of the E. ansorgii species group, by the absence of a dark bar under the eye, and from members of the E. sangmelinensis group, by the presence of two dark bars on the lower jaw, which are absent in the E. sangmelinensis group (Ref. 94049). Epiplatys atratus is distinguished from all other members of the E. multifasciatus species group by the possession of a dorsal fin inserted above anal fin ray 8-10 versus 10-13; in large males the lobes surrounding the supra-orbital laterosensory system almost cover the groove versus a completely open groove in large males of other species; from E. multifasciatus, E. mesogramma and E. phoeniceps it is additionaly distinguished by the absence of broad dark bars on the flanks and fins of males without markings versus all fins spotted, the anal fin provided with two or three dark blotches as extensions of the dark bars on the flanks; Epiplatys atratus shows only narrow dark bars on side, whereas the former species have broader dark bars and only sometimes narrow bars in between (Ref. 94049). It is further distinguished from E. chevalieri by the presence of narrow vertical bars in smaller males and in females versus complete absence of vertical bars (Ref. 94049).

Description: Slightly compressed and deep-bodied, exhibiting marked sexual dichromatism with large adult males black without bars, females brown with up to 14 narrow dark bars, median fins in males large and unspotted, small and spotted in females (Ref. 94049). Dorsal profile slightly convex, greatest body depth approximately at level of pelvic fins; ventral profile slightly convex from head to end of anal fin, concave on caudal peduncle (Ref. 94049). Snout pointed, mouth directed upwards and prognathous (Ref. 94049). Dentary and premaxilla with an outer row of large and several inner irregular rows of smaller recurved unicuspid teeth (Ref. 94049).

Colouration (in ethanol): Large males of Epiplatys atratus differ from all other Epiplatys species by the almost dark grey to black body colour; small males and females differ from all other Epiplatys species by having 3 narrow oblique black bars on the flanks just behind the pectoral fin (Ref. 94049).