one of my first tanks i had was a 55 gallon with 6 red belly piranhas in it. one day the neighbor's cat drug in (what i thought was) a stillborn baby puppy. not sure what kind it was, but it was about 4 inches long with no hair. i dropped him in the tank and it immediately start squirming. sure enough this attracted the piranhas and within 2-3 minutes there was nothing left but a bloody mess and a chewed up carcass. pretty kicka$$ 

