Ok ive read the things you guys have answered about my Red Belly piranhas so now could some tell me if i got this right. Ok i should get two more piranhas so they work as a group, and not just one because they will compete. also eventually as they get bigger i should move them to like a 55-75 gallon tank? for food brine, blood worms, insects, feeder goldfish, guppy etc.? and lastly is it ok that the two more piranhas are going to be smaller then the first one i got? THANK YOU BIG TIME. ill probabely have more questions so thanks for answering these.