Well I am getting a 55 g tank in about a week or so. and i was going to just move my oscar into it along with a couple more. however, it has come to my knowledge that a 55g is only enough room for about one oscar, and two if you want to push it. so...now im looking into piranhas. i know very little about them. how many could i put in a 55g tank. i also have many other ?'s. all the information you have for a beginner would be greatly appreciated!