well if you are wanting all-out aggressiveness, piranhas in general are gonna disappoint... most people get into the hobby because they want some blood-thirsty aggressive fish, but end up realizing that they aren't as vicious as they are made out to be. i would give piranhas a shot tho, if you end up with an aggressive fish after a few months, you lucked out, but if not, you may end up liking them anyways.