A couple months ago I was at the LFS (home). I saw that they had just got a few 1" red bellied piranhas in. I'd never kept piranhas but I thought that since they were so small that I'd give it a shot. I bought two with the intention of letting them grow out in a 10g with only a 1 1/2" convict in it. I thought that they might gang up on the convict, but I figured the con was mean enough to hold his own. They were fine for about a week, but when I turned on the lights one morning, I only saw the con and one p. Upon closer examination, I found a tiny little skull in the gravel that the con kept playing with. I didn't expect that at all! The con and the p that was left got along fine for quite some time until I gave the p to a friend with a larger tank.