Here we go, the "it's nature" crap again....like they'd naturally be hand fed mice/goldfish in the wild - hmm - yep, that's natural.
Anyhoo, I dont know anything about Ps, but Gator sounds like the expert - I though (and forgive me if I'm wrong) that pirhanas in the wild are more likely to eat dead animals, not live ones? And it was just bad press about them being vicious killers.
Like I said, I'm probably wrong...but if I am, blame Animal Planet lol (incidentally, I watch it more since Steve Irwin died, now his shows - that was animal cruelty).
First I want to say thank you to CFC for bringing this thread back and spending his own time to make it a better thread for all of us. I asked him what happened to it and he said it got out of hand, he could have just left it at that, and had every right to, but he went out of his way to clean it up and make it available to all of us. So again Thank you, CFC.
You're partially correct, Lisa. Piranhas will eat dead animals in the wild.
The Pygocentrus (Pygo's) travel in loosely formed shoals where competition for food is much greater so they will look for anything they can get. They will sometimes kill healthy fish but that wouldn't be the norm. They are more or less scavengers and seek out any weakness amongst a school of fish. Piranhas are one of the best at seeking the tiniest of wekness that even we wouldn't notice. The vibration of a fish swimming differently, the way it floats when still etc.
Serrasalmus, like S. rhombeus (rhom) sometimes travel in loose shoals but they are much smaller shoals and they are more apt to be alone and not travel among that shoal for very long. They are the ones that it's harder to convert to non-live fish.
I'd say that all in all, piranhas are "opportunistic" predators. They are some of the quickest fish in the water but they can't go for long periods, it's more like short bursts so they don't waste their time going after healthy fish as much. They are very sneaky also. They will catch their prey in different ways. They will ambush, straight out swim and catch and also stay visible for other schools acting nonchalant and circle, with each few circles getting closer and closer until he's within attack range.
Edit: The bad press started with theodore Roosevelt and ihs travels to S.A. The locals put a cow in the water and the piranhas tore it down to the bone in just a couple minutes. he came back to the US and talked of these piranhas as man-eaters and pumped them up. Which I would have thought so too but read on...
Since then, it has been said that it was staged. They kept the piranhas in side the same stretch of river withing a fence, starved them (I don't remember how long tbh) and then when Roosevelt was there added the cow to the starving piranhas.
In some cases like this, I agree that piranhas can be extremely vicious but it's not a very good indication of the species. I would think most fish that were starved like this could become "terrors" trying to eat so they can live. My Zebra Danios go after food much harder than most piranhas I've had.
The locals swim, bathe and even cut their fish right in the river where piranhas are present. They'll even drop the innards to the piranhas and from just a few feet away they swim in, take and hurry away as fast as they can. There
are cases of someone being bitten but they are few and far between. The locals know more about piranhas (RBP's mainly) than any of us do and they aren't afraid of them, so they can't be all that bad.
) and all the animal cruelty shows that are on now. I can't stand that people are so mean to animals like that. I remember one of my friends did a science project with goldfish and how caffeine affected them and I was ready to call the RSPCA on her because she was keeping them in small, unfiltered bowls. Piranhas and goldfish are the most misunderstood fish ever, I hate it so much. 
i feel the best way to deal with stuff like that is to ignore it. lol the less people who see it the better.
