Does a single fancy goldfish really require 80 gallons? We are putting it into a 30G but it is going to get 100% water changes every week. If the fish grows up big it will take a while and we will get it into a bigger setup.
You do not need an 80 gallon tank for one fancy goldfish...
They grow to about 6 inches max. The 30 gallon should be fine.
It is common goldfish that are the real whoppers, ranking in at about 1 foot, and should only be kept in ponds.