Differs from the other three known species of Osphronemus in having oral teeth increasingly enlarged and externalized in large adults, a condition apparently unique within anabantoid fishes. In large specimens examined, over 40 cm SL, all of the jaw teeth are enlarged, especially those in the outermost rows, which lie on the external surface of the jaws entirely outside the mouth when it is shut. Coloration of juveniles and adults also is diagnostic. Small juveniles have 6 or 7 vertical bars and a supra-anal dark oval spot, none of which are retained by adults and subadults. Juveniles over about 10 cm have a reddish orangish stripe on the lower part of the head and breast, a feature not observed in any other species. All adults have extensive dark (almost black) areas ventrally and pale areas dorsally. Several large specimens (especially from Stung Treng market, Cambodia) with large and irregular red blotches that superficially at least look very muck like bodied bruises.