Elongatus

[Googz]

Piranhas are not that agressive, unless they are hungry. If you want something that will chase your finger save the 140 and buy an oscar. An Elongatus is the best bet but as others have said it theres still a posibility that it wont be agressive

 

[cepon3]

Piranhas are not aggressive fish at all.. In the wild Serrasalmus sp. are fin and scale eaters.. so when you throw another fish in with them they are doing what their brains are hard-wired to do.. rip the fins off the other fish.. which is hunger not aggression just incase it wasnt clear.. I suggest you get a fish that you want for its looks and not its "death in a box" persona.. youll be much happier that way..