I'm amazed nobody addressed his 2 piranha by themselves idea! Ivan, if you're not going to have a solo, then 3+. If you have just 2, it's only a matter of time before you'll end up with just one due to their obnoxious pecking order. Having 3 or 4 gives the underlings more protection, since the head honcho has to lay him/herself thinner to keep everyone in line. AND EHXON: That fish looks like an RBP (RED BELLY PIRANHA) to me, just like you don't look identical to your next door neighbor, not all piranhas (even of the same species) look the same.