Not true... I've been a piranha collector, for 9 years now, and there are many different species of piranhas. Pygocentrus species are shoal fish, that are basically shy, and docile. Where as the serrasalmus genus, with the exception of maculatus, and geryis, have to be kept in tanks by themselvs, individually, because they will attack anything you put in the water, including your hand. The whole "blood" thing is completely a myth. I feed mine mice all the time, and theyre not bloody. Its hunger pains that get them to attack, Nothing more. The piranhas you're talking about in question with the cow, are Pygocetrus Notatus, Nattererri, Piraya and Ternetzi. This theory was made popular by Teddy Roosevelt, during his trip to south america. The locals blocked off the river, on both side of a walkway over the water, with nets, and filled the area with piranhas, starved them for days, then threw a cow in the water. Killer first impression of a foreign country eh? And as for tank size, 15-20 gallons per fish, is the bare minimum for ANY piranha, and most need bigger, but you can get away with 15-20.Blue said:And the theory of them eating a cow may be true but that applies only if the cow has wounds which will most likely trigger them to attack. Piranhas don't attack until their prey has blood to attract to.
Another thing, their reputation of attacking humans is far from true. They are actually shy and will attack only if provoked.
I hope I've been helpful, and Blue, I wasnt trying to argue with you, just shed some light on our misunderstood friend, the great piranha. Good day to everyone!