I agree with everyone else. I would say 1 fancy in a 30G because it wll be the easiest on you and the fish. you could keep 2 in there, or 1 in a 20G, but you would have to do a lot of work and overfilter.
You're a brave person to announce such a thing here; luckily there arent any fish police or they'd have already called them on you. LOL!
Of course, I would agree in this particular case; your tank is way overstocked with 80 inches of fish in 20 gallons? Are you serious? WOW! You must have some major filteration to keep them all living.
Then again, I guess I'm not much better because I currently have a comet, 2 koi, and 2 calico shubunkin in a 20 gallon with 2x 30gallon bio wheel filters. The fish are all about 3-4" right now and I understand that an upgrade will be needed in the future.