I've had my goldfish for quite a while now, with one fish from my initial group, and four others that were added later on. I've had these five fish living together for a good amount of time and have become accustomed to one another. Today I wound up purchasing another goldfish, a tiny one eyed comet. I have another one eyed fish in my tank so I thought it would be a cute little addition. My older fish are much bigger than the new little guy and have been ignoring her this whole time. I caught one of them chasing her for a second before getting scared and scurrying away, and the others aren't passing the middle of the tank, leaving all five of them on one side and the baby on the other. Are they ever going to accept her or is it unlikely?
Goldfish are usually too themselves and wont bother much with other fish. But that doesn't apply to all Goldfish! I had some that seemed to be more aggressive to the other fish. I suggest to watch your fish and see how they treat the other fish. If they don't seem to get along, then maybe you should separate them.