Fishkiller is correct in that true Malaysian bloods (P. brongersmia) are rare in captivity and very difficult to distinguish visually from those of Sumatran origin. However, wild caught Malaysian specimens are on average much more aggressive than wild caught Sumatran bloods. Malay specimens that are captive born are usually similar to captive born Sumatrans, but act more alert and sometimes aggressive, but usually tame rapidly as captives. I have 2nd and 3rd generation captive born specimens of both types and the Malaysians still show this behavioral distinction in that while they never attempt to bite or show any type of aggression, they are however more active and squirm around some when handled, as opposed to the typically calm and laid back Sumatran temperament.
Kelly