I have found that they have way more personality and interact with their owners way more when they are kept by themselves, I guess this is because they don't have to constantly live in fear of another fish taking a chunk out of them, probably why most piranhas that are schooled together are more skittish as well, this piranha and my caribe piranha have the most personality out of all my fish.Wow! Never thought I'd see personality like that in a piranha! Not that I know much about them but usually hear stories of how boreing they are lol. This guy is damn cute wiggling away all excited for his master to feed him