Well.... I wouldn't suggest putting your hand in a bowl of piranha's... but from what I've seen they are made out to be alot worse than they really are... My friends dad (when i was a kid) was a fresh water fish seller, and he always had piranha's, puffer fish, all kinds of crazy fish.... and they never had any problems with em... like i said before, the puffer fish are the ones you need to look out for, bit the tip of my friends dads finger off lol...