Well my (Serrasalmus Elongatus)Pike Piranha , is definately the most aggressive fish I own or have seen for that matter, I have 6 RB's, 1 Black P and this guy out does them all. He constantly patrols the tanks and as soon as a food item hits the water, he grabs onto it and does barrel rolls until it is minced meat, he gets in such a frenzy he actually bit the top off of my plastic plant. He is tons of fun to watch not at all shy and is very active, I would highly recommend one of these little devils to any piranha lover . I thought $75.00 was alot , but it was definately worth it 
