Gourami Dropsy Treatment

[Olycius]

Hello, I currently have a 120g tank, and I left my house for a few days, and when I came back it looks like one of my fish passed(he was a new addition and I believe he was stressed out due to being chased by others in the tank). I assume he was in there for at least a day, and when I tested the water there was an ammonia spike. So I checked all the fish and two of my gouramis got dropsy(one had it pretty bad and the other was showing early symptoms). I immediately moved them over to my sick tank and did a 40% water change on my 120g. The numbers on the 120g are steadily going back to normal, and I am closely monitoring the other fish. As for the sick gouramis, one passed and one is still alive. I know that it is hard to treat, but what methods have worked for you all in treating it? He seems a bit more lively today, and would like to see him make it.