This was like a 5 second google search:
"The basic rule you should strongly consider following is that you need one goldfish per every 10/15 gallons or so. Some people say you need 20 gallons per goldfish but realistically, not everyone is going to have a 20 gallon goldfish bowl
with only one goldfish in it? Goldfish can in fact survive in a smaller goldfish bowl but this will stunt their growth and potentially shorten there life-span. This will require a lot more maintenance to keep the bowl clean and the goldfish healthy (see Nitrogen Cycle
for more info)."
While I still say 20 gallons per goldfish, I will take 10-15 per fish. Do a little research people...