Caribe pirahnas are the most agressive SCHOOLING species there is, in consideration of the exodons, which are mean little bastards and you could keep a larger shoal than you could with caribes... Then again payara are sick, but sometimes are like wolf fish and sit still alot, well it kinda goes like scombs dont move much, tats (red tail) move more, and armatus move the most. That list goes by size too so you could keep a group of scombs and probably a pait of tats, but a armatus should be housed alone cuz of size. Im not a wolf fan but love payara, just my opinion, but look into these fish and see what you would like.
