Ok, so I've seen countless threads asking what the most aggressive Piranha .. Cichlid .. Arrowana .. Etc is. I want to know what everyones opinion is as to what is the most aggressive, realistic to keep, Freshwater fish. It can be Territorial aggression or Predatory aggression or just a mean S.O.B. My only rule is that it has to be able to live in an aquarium that a hobbiest can afford and maintain. Basically I don't want people to say things like the Bullshark which can live in freshwater, because obviously the average person can not keep one as a pet. No real meaning behind this thread other then I thought it would be an interesting topic.