I felt sorry for a lonesome RBP in a tiny tank today, so I bought it. Pushing 4 inches.
I kept 3 RBP's years ago and had them eventually with a spotted gar and a shovelnose. The worst that ever happened was the gar killed a pirhana.
They were not aggressive at all. They would sometimes leave a feeder goldfish untouched for over a week.
Yet this one, my god.
I put him in on his own and he started attacking all my fish, who are all bigger than him. Tried to bite my lovely bichir several times, went for my hujeta, tried to bite the oscar.
I quickly fed him some beefheart which he gobbled up, then he started attacking the fish again. He attacked everything but the wolf.
Then I noticed he bit a chunk out of the bichir's tail, just the fin bit, so I thought you little bastard I'm gonna eat you.
Then I just decided to quarantine it until I set up a tank tomorrow.
I may as well keep it, not often you see a lonesome Pirhana as aggressive as this.

I kept 3 RBP's years ago and had them eventually with a spotted gar and a shovelnose. The worst that ever happened was the gar killed a pirhana.
They were not aggressive at all. They would sometimes leave a feeder goldfish untouched for over a week.
Yet this one, my god.
I put him in on his own and he started attacking all my fish, who are all bigger than him. Tried to bite my lovely bichir several times, went for my hujeta, tried to bite the oscar.
I quickly fed him some beefheart which he gobbled up, then he started attacking the fish again. He attacked everything but the wolf.
Then I noticed he bit a chunk out of the bichir's tail, just the fin bit, so I thought you little bastard I'm gonna eat you.
Then I just decided to quarantine it until I set up a tank tomorrow.
I may as well keep it, not often you see a lonesome Pirhana as aggressive as this.
