It's B. vaillantii IMO...
Absolutely right, not just about the max size, they can grow really fast also.
But in my experience, I think we can restrain the growth rate, depend on feeding frequency, and food quantity.
Maybe it could give us more time to prepare better home for them (if we force to do it, but still, starving our pet isn't good option at all).
Piraiba very tough fish anyway, very endure in hunger.
It can be said, that we usually not aware that our fish was actually hungry.
I still remember when my fish got beaten and severe stressed, but still could heal itself without food for weeks!
Also I've learned from tyjo1334's piraiba thread, which his fish indeed, very very similar to one of mine.
I found that he raised his fish from 2.5" to 14" size in 2 years period.
In my case, when I really pushed on feeding, I've raised mine 6x faster than tyjo1334's did to his fish.
