The scarlet soldierfish has an oval body, compressed laterally, which can reach 7.8in (20cm). It is recognizable by its large eyeballs and its red color on the back, lightening towards silver on the belly. Its very visible scales have a darker border than their center. The anal, dorsal and caudal fins are denser red at the extremities with a very thin white border, except on the first dorsal and pectoral fins.