As other members have already mentioned, the stock you have now is more than enough.
However, I just wanted to share my experiences with fancy goldfish "tankmates."
As I am sure you know, goldfish are coldwater fish and should be kept with other coldwater fish in cases where an owner wants a mixed species tank/pond big enough and filtered enough to support the fish. Now, fancy goldfish generally are said to be kept with other fancies, and for good reasons: Fancies are NOT very able-bodied, especially compared to their sleeker, single-tailed cousins, the common goldfish and koi. They will have a much harder time reaching food before the more agile fish sucks it all up, slowly starving to death if not properly monitered/managed. I could argue that a telescope and a normal-eyed should be monitored because bulged eyes are enough of a disadvantage to lead to starvation when housed with other fancies.
And perhaps you aren't wanting another big showcase fish, but consider perhaps...rosy minnows, like I did at some point. They don't get terribly big, they are cheap, and they add more visual interest to the tank. But man. This would be a terrible idea. Maybe with some larger goldfish they would be ok, but miss feeding them one time and it is almost inevitable that they will go after the easiest meal they can find. In my case it was tiny pearlscale I had purchased just the previous day. Round, tiny, and slower than their other goldfish siblings, they did not stand a chance against the small school of hungry rosies.
So please be careful with any "compatible" fish that you come across if you still feel tempted to add more.
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