A friend of mine gave me her two goldfish about three months ago , they were in awful condition - living in the tiniest tank ever. On the day I went to collect them, one of them had died - leaving just one behind. My friend told me the remaining goldfish would bully the other goldfish. They would often fight and the surviving goldfish would ram the one that has now died in to the tank wall. Now, I have the goldfish in a big tank. He looks shiny and happy - spends his time swimming and eating (bare in mind when I got him he was floating on his back.) My question is, do I buy him a friend or would be happier alone. I'm worried he would bully the other fish but that could have been because he was in a small tank. What do you guys think?