Betta nuluhon

Betta nuluhon are brown to dark brown with body scales rimmed with bright blue. A dark stripe extends from the upper jaw through the eye to the opercle edge, a dark suborbital stripe and a chin bar are present. ^[2]The body consists of a yellow dorsal region, black lateral regions, and a reddish ventral region. Male B. nuluhon may exhibit a greenish-blue iridescence on the opercle. The dorsal fin is brown with 4 to 6 traverse bars, the caudal fin has 12 to 16 dark transverse bars, the anal fin is plain with a reddish-brown margin, and the pelvic fin has a whitish second filamentous ray. The fish examined for this study had standard lengths from 39.8 to 62.6 mm.^[2]

Contrary to the trend of being situated in stagnant peat swamps with a low pH and little to no dissolved oxygen of most species of the Betta genus, Betta nuluhon is found in hill streams with fast-flowing, high-oxygen, and a neutral pH. It is found in the Crocker Range Nature Reserve in Western Sabah.^[2]