You'd be surprised what fish can recover from. Doesn't look like the fish is ready for that transformation, yet, so give it a go in treating the tank as I mentioned with a mild antibiotic and keep nitrates low.
Keeping low nitrates seems to be a key factor for preventing the spread of disease within a tank and helps allow for more effective treatment.
We do not know how the fish came down with this sore. Could have picked on by the other gourami and wounded. Could be parasitic. Could be and most likely bacterial. Bottom line, whatever it is, created an infection. What I see on your dwarf is something I commonly see on dwarfs, especially when there are several. I've been told different information about these infections, but do seem to be dwarf gourami specific, so may not bother your other fish. I've never seen these particular sores on any other FW fish. Others have told me it may be parasitic and specific to the gouramis. In my experience in treating these sores is I've always been able to heal them up with antibiotics. I personally like to mix malachite green and methylene blue. In cases with sensitive fish, I'll do a quarter dose of each which would equal a half dose of medication total. Remember to remove any carbon from the filter and replace with fresh carbon after treatment.
