Is this a good fish setup?

I have a 20 gal tank with 12 male guppies. In the future I may give some away but I have them for now. And I was wondering if a dwarf gourami would be good?!? Can u tell males or females apart? If so pleSe link pictures to the answer if possible. And if I get one, could I get another one in the future and they be civ together? Anything I should no about them befor I get them