What is the difference to bintan?
If I knew I would tell you. Nobody knows exactly. Both forms are obviously closely related. They even maybe genetically identical. But we have no information on that so far.
P. bintan is a scientifically described species with a known sources of discovery. It was described by Kottelat in 1998 and two islands were given as source ot its natural distribution: Bintan and Bangka. So, Sumatra does not belong to that list, or better: It is not mentioned in the scientifical description. The spec. Sentang has first appeared named “sintangensis” in trade without a clear mention of a source in 2006 or 2007.The latinizied name sounded similar to a scientific description, but that was a fake by the trader; perhaps he was himself unclear about that or he thought of better deals. Nobody knows. Anyhow, the name was changed to spec. from Sentang (Sumatra), and it was clearer what the source was: an unknown place near the Sumatranian town of Sentang. That means: We must separate both, because it is wholly unclear what the exact relation of the two amounts to.
But: Anybody who knows both forms sees clearly the close relation. The spec. Sentang is identical with bintan or it is a close relative. If it is identical, then the list of the natural sources of bintan given in the scientific description of Kottelat’s is incomplete (this is well possible, I should say: it is highly probable). If it is not identical, it most certainly is at least closely related.
The case cannot be solved before we have genetic data. Presently we must separate the two and say, that spec. Sentang is a bintan-like form stemming from Sumatra, and it is to be distinguished by a slight differention in the colouring of the male: it is slightly less markedly coloured, with often a little greenish tinge in the fins. It should not be kept together with bintan in one tank, for it is – to say the least – definitely stemming from a differnet place far away from Bintan and Bangka, therefore at least a local variant of bintan but possibly even a different species. It is probable however that both forms could be crossed, but we may not have any interest in mixing the forms until we don’t know of their status. We should not produce mingles of different species if we have no knowledge on this matter.