Hi Isis
I have had a lot of fish with my Discus Community tank. One thing you will have to take into consideration is that Discus love much warmer temperatures than most tropical fish. So with that, I know that cardinal tetras are one species that work... so do Angel fish, GBRs Bolivian rams. I do not believe that cory cats do well in temps of 84* -86*.
I think if you stuck with South American fish you would find fish that are compatible. I also have A. Rainbows in my tank with the Discus, but I do not keep the temp up as high as most would require them to be at. My water temp is around 82* which is on the low end for Discus, but I have had my guys for over a year and a half and they are doing fine. Ive never had Gourami's with my Discus, so cannot give you any advice on that combo.
If you look at my siggie for the 55g tank, you will see who is with the Discus there, and they get a long fine.
