I keep a solo caribe, and he's extremely aggressive towards other fish, but not towards me. He acts timid around me -- won't chase my finger or anything like that -- but if I drop in another fish, whatever it may be, it's dead in less than 2 minutes at most. He also looks fantastic, and a lot of members on Piranha Fury have stated that he has great coloring. I started a thread in the picture forum on this site, but people here seem not to care much for piranha. I love them though, they're great and beautiful fish to keep.