No. No goldfish of any sort in a 20 gal as a permanent home. The normal body types and shubunkins grow to an average of 10 inches, most get well over that at 14 inches. The fancy types generally get to the size of a big orange or cricketball. Even one goldfish would be stuck for space in a 20 gallon, you certainly cannot keep a combination of any sort in there. The best thing would be for you to get tropicals. All you need is a heater, all the things you do for basic tropicals are what you do for goldfish, but with a heater. The process is exactly the same and no more difficult as many often assume.