Atherion elymus has an elongated, compressed body with a small mouth in which the upper jaw does not extend as far as the front edge of the eye.

The colouration is greenish gray on the back and whitish on the underside with a wide silvery band along the flanks which extends to the caudal fin.

Small dark or black spots are normally scattered along the lower part of the flanks.

[3] Atherion elymus occurs in the western Pacific Ocean from Japan in the north south to northern Queensland and east as far as Fiji.

[1] This species was described by David Starr Jordan and Edwin Chapin Starks in 1901 from a type locality of Misaki in the Kanagawa Prefecture in the coast of the Sagami Sea in Japan.