I agree. When I was young, I got 12 red-belly pirahnas and they aren't aggressive at all. They are very skittish, especially if you walk by or turn on the light. They would scramble under the driftwood and take forever to come out to eat. I first fed them feeders and they still aren't as vicious as people think. I then started to feed them beef heart. They grew very fast with the beef heart and I got rid of them because my tank was too small and they are illegal where I live. Pirahnas are just over-rated. The Asian Catfish, I believe, are the most aggressive if you mean what kind of fish quickly eats another fish. The Doctor