I'd think the diet is as important or more important as the place of origin and water chemistry there. Wesley Wong, our famous USA vendor and pioneer who sells a lot of rare mahseer, says e.g. that tambra has to consume some flowers or flower buds and figs to gain a remarkable red coloration.
Thanks. You're quite right. As usual, I left something important out of what I thought was well planned. Completely forgot about that. Haha. Yes. Diet. I was told by angler friends the Stracheyi especially in the north west, a cherry bomb (a type of local wild fig found there) is one superb way to fish them. That's the one item I'll find difficult to buy among other riverine fruits, which I may never have a meaningful list let alone procure them.
Your friend Wesley Wong could be completely right on the Malaysian Tor Tambra, but since it'll be very difficult to include a reasonably comprehensive list of riverine plants in their menu even for someone staying in the same country, we may have to rely on another proven theory, genetics. I'm confident Wesley would know true red mahseer are mostly found only in northern east coast of peninsula Malaysia with those from Tembat river being the gold standard.
My solo mahseer is from Tembat (as claimed by seller). I like it's golden shine when there's sunlight, and at night it shows a deep red. I won't pretend to know how to appraise the quality as I have limited knowledge on what's ideal, but I like mine the way it is. Been 4 months with me now without plants as food and I didn't notice any further changes in colour. I did fail to retain its vibrant colours if freshly caught, but I hope the good genes will help to maintain current colouration. It's still currently solo because I planned on a mahseer collection before the oil crisis, then global pandemic, national lockdown and the rest should be self explanatory....?.
The fruits though are proven to make the flesh more fragrant for consumption and is widely used in commercial farms although they use mahseer that aren't red but dull grey and some argue that they are Tor Douronensis sp. If you want to know, nope, I never ate one before, so I won't know the difference. ?
I apologise if I'm writing too much, a habit I usually have when I'm communicating on something I'm very interested in. There are so much more I want to learn on Mahseer fishes. Amazing fishes and truly breathtaking colours when freshly caught from the wild.