Common Goldfish Tank Size
Let's say that your summers are way too hot and winters are below 0 (or your local laws prevent you from making a pond), but still want to keep a nice pond type goldfish. How big should your indoor aquarium be? I'm hearing the most crazy extremes for what tank size I should keep for a slim-bodied goldfish (common, comet, shubunkin, wakin). NOT koi. I want to know what your opinions on. And DON'T SAY A POND without specifying the gallons and the filtration method, because I can easily just bury a five gallon bucket in the ground and call it "a pond".
Many people seems to have a mentality that "whatever they think they should keep goldfish in is too small, and whoever says the most amount of gallons per fish is the smartest." This lead to me getting answers anywhere from 125 gallons for a single fish to 600 gallons. I'm sure no one in their common sense would only add a single 8" fish to a 125 gallon aquarium. The only information I could find online says somewhere between 30 to 40 gallons per fish, or 10 to 20 gallons for each additional fish.
Tell me what you think is the correct water volumn for a single slim-bodied goldfish. I'm really wanting to know because I'm looking to get a couple. If you can also source your post with a link to a study or any site that can back you up, you will be highly regarded. I'll tally the results.