Betta rubra, occurring from Meulaboh to Sibolga in north-western Sumatra, is formally re-described based on freshly collected preserved and live specimens. The species can be differentiated from other members of the genus by the combination of the following characters and character states: an iridescent light blue patch at pectoral fin origin, alternating black bars and red blocks ventrolaterally on the flank, presence of a dark triangular patch below the eye, absence of red twin bars on the opercle when preserved.
