They definately exceed 12". I kept 5 of them for about 8 months. A couple of them went from 10" to 14" and became very thick. The other 3 weren't far behind. Real gluttons. I ended up giving them back to MFK member "masheer".
Mahseer is the best with cyprinids but yeah the yellowfinned barb or Peek from SouthEast asia, here is a picture of a large fully grown one from Thailand