Fine picture, fine animal, but sumatranus? Not likely. The specifically characteristic big round black spot at the end of the dorsal is missing entirely (mentioned as species-characteristic in the original description) and the black stripe at the border between anal and body is missing, diminishing towards the tail. Nevertheless: very interesting fish, close to former spec. Palangan from Kalimantan Tengah (which is thought to be extinct because of complete destruction of the only habitat known. But ….)
Please, send the picture to me personally at my personal address. I shall forward it to other German experts. And we should discuss it in Hamburg.