Hi joanne61451
It sounds like your gourami has an ulcer caused by a bacterial infection, aka finrot.
You might try giving your tank a big water change, (50% or so) and vacuum the bottom. Then give it a dose of MelaFix. That's often enough to stop the infection and help it heal. You can add this to the entire tank. If it doesn't show any improvement within 3 days or so, it would probably be best to isolate it and go to a stronger medicine such as Kanamycin.
The important thing to think about is why your fish got sick in the first place. Bacterial infections are caused by bacteria that are commonly found in tanks. It is only when it is subject to some kind of stress that its immune system weakens and it gets infected. Some of these stresses are overcrowding, overfeeding, temperature fluctuations, aggressive tankmates, high nitrates, low oxygen content in the water, and very often, insufficient or infrequent water changes and bottom cleanings.
Unless your tank is very lightly stocked, it would be a good idea to increase the frequency of your water changes and vacuumings to every week. The filter only needs to be rinsed out when it appears to be starting to clog.
I hope your fish gets well soon.
