piranha have gained a reputation for being vicious killers, a little bit like sharks. I don't suppose those awful films help, remember the one that starred Lee Majors?
Of all the species of piranha, there are only a small handful that eat meat, the rest of them are vegetarian. Contrary to popular belief, piranha are not a dangerous fish and do not go around eating anything and everything they bump into. They normally feed on dead and dying animals. The exception is baby egrets, rather horrible if you've ever seen footage of it.
Having said this, we are talking about the wild, I don't think I would feel happy about keeping piranha with other types of fish. If your oscar became ill, it would become an instant target for attack. So I would agree with everyone else, I don't think it's worth the risk of keeping the two fish together, even though they do come from the same part of the world.
