We had a tank of about 10 or 12 of these in the pet store I once worked at, with a few Headstanders and Anostomus to boot. Anyway, we manage to train the whole lot to eat only meat, and they were more vicious than any piranha I ever saw. We'd drop the biggest feeder goldfish we could get (or even an ornamental gold if no one was looking) and every fish in the tank would be gnawing furiously on it's own little corner of it, with half a second. The gold would be a skeleton in under a minute sometimes. Which is why I laugh when I see books that say, "community fish, eats only plants."
I doubt it would work this way in Jim's Aquarium though.