Normally, the goldfish live outside in a 300 gal Rubbermaid. I have two common goldies from about eight years ago, and four more fancies. The fancies are definitely more delicate. Drained the tank for a winter overhaul this afternoon, and found my prettiest on her side on the bottom. Her color is good, no pineconeing, no sores or fin-rot. She is a bit thin, and weak. She is now inside in warmer water in a half-full 64qt Sterlite with a bubbler. I'll have to do daily water changes. She is a big fish, and the recommended min. is 20 gal per goldfish, but that is the best I can do for her for now. Not sure she'll make it. I have a box of misc. fish meds, but I don't know what is wrong. The last goldie I had to over-winter two years ago came through fine, but he just had a bit of fin rot - easy to treat. Once they are in the house, they are in until Spring. I'm not putting a warm fish back outside in 40F water.
Anyway, what really struck me, was how much I didn't realize I missed having a fish in the house. It's like they live in a different dimension, and there is NOTHING more beautiful than a goldfish. She is such a beautiful creature, I hope she gets better.