Has it not come from Wes?? I assumed it has.
I used to see this kind of piraiba only in Wes' photos and no other vendor.
Wes and I have identified it as a true piraiba in our private communications with you. It looks different from other piraiba babies we see with spots all over, not just rear half, and the spots are smaller. But it is a piraiba as it doesn't look like a false piraiba aka B. capapretum. That fish has large spots all over its body and I have never seen anything different. All the capas I've seen looked consistent.
As for another trait, the head structure of capa differs from this fish, which has the head of a true piraiba.
My experience is probably covered in its current entirety in the thread dedicated to my current 3 piraibas - one's from Wes, from Suriname, got it already large at 18" and the other two I was told from Peru, from Discus Origins Mark Chen, these were ~5" and had small spots all over:
https://www.monsterfishkeepers.com/forums/posts/7755699