when I kept RBP I had a shoal of black skirt tetras in there as well and the P's left them alone, of course that also goes back to the well fed theory.

I believe it could happen for a while if the rbp's are large and well fed.

The 2 main reasons rbp's kill are for food and territory. A fish that is too small for them isn't worth the effort to chase very long if they are well fed and the mollies will learn where the territories of the piranha are or be eaten so the ones that learn fast can stay alive for quite a long time.

Although piranhas are extremely territorial, much moreso thatn any cichlids I've ever kept, rbp's aren't the bloodthirsty killers that most would like you to believe. Most Pygo species aren't in fact. RBP's are actually skittish and afraid of their own shadow. Serra's on the other hand are a different story. They'll kill just because they can and hate everything.

It's rare in home aquaria for a piranha to get larger than 10-12" it's certainly possible in large enough aquaria. Piranhas never stop growing throughout their lives and can live for 30 years so it's definitely possible.

This post has been edited by Gatorbait: Jul 8 2008, 12:19 PM