Dang, I gotta poo-poo your idea
Goldfish, when properly cared for, can live for 20 years and grow 12" long. They are strong swimmers and require a space long enough for them to exercise swimming back and forth. A large ceramic pot isn't going to provide a good home over the long term for them, no matter which way you look at it.
Here's my webpage on the indoor GF pond we used to have in our old house...
http://www.lostmymarblz.com/indoorpond.htm