What fish can you mix with a gold gourami in a 20 gallon long?

I have 4 gold gourami's-one adult and 2 smaller ones, along with 5 jelly bean parrots, 2 green severum's, a half dozen cory cats And several blue gourami's. However i have a 75 gallon tank and the severum's and 3 of the jelly beans are full grown and are saucer sized. And they are all peaceful to each other. 

However, if you don't want to spend that kind of money (jelly bean babies are $15+ each), you can get some danios or neon tetras-remember to get at least 6 of each, maybe 1 or 2 cory cats and even other kinds of gourami's.  Just be careful with Dwarf Gourami's-they are not strong swimmers and can easily get stuck in the filter. 

Agold gourami would do better in a larger tank with room for larger tank mates.

But if you plan to keep things as they are, you want sturdy fish that stay out of his territory. 

8-10 kuhli loaches and a dwarf pleco like a bristlnose or rubber lipped.

or you could try Maybe black neons and cories, or cories and odessa barbs.