Black Moors?????????????????????????

You are currently massively over stocked. The current fish either need to go into the other tank, a pond or be rehomed. Also comets and other long bodied fish don't do well with fancy goldfish as they are much faster and will get all the food. Black moors should be in a species only tank (or with other goldfish with fragile eyes bubble eye, telescope eye, etc) as their eyes are very fragile and could easily be injured by a comet or faster swimming fish.

Once you deal with that a single black moor could live in that tank its entire life. 2 need 30-40+ gallons.

Edit-
Ok, that's what I would thinking you were doing.

Your tank is way overstocked, either get a bigger tank or get rid of all but one.
1 Fancy goldfish needs 20-25 gallons double filtered, and 10 gallons for every additional one.
1 Comet needs 75 gallons and 20-40 gallons for every other ones.
I'm surprised your fish haven't died of ammonia poisoning yet.
Are you aware that comets can grow to be over a foot long?
Fancy goldfish can grow 6-8.
Do your research, please!

Even with the 100 gallon for your two comets you need 100 gallons alone, and for your 3 fancys you'll need 40 gallons additional.