Fish floats vertically...swim bladder?

yeah that doesn't sound good.

you can take him out of the tank and Quarantine him...otherwise your other fish are at some risk, if its e.g. a bacterial infection.

I'd ask some other folks to advise on meds. I don't know enough.

If it is a bacteria, all your fish have been exposed by now anyway.

I'd do some big water changes every day. If you have another tank, pull the gourami and wait for someone to recommend a medicine for swim bladder - I have no experience with this. Make sure you put the gourami in a cycled tank, or a tank with a cycled filter...

Large water changes reduce the numbers of bacteria, molds - causing fungus, and parasites. This is your best bet for your main tank. (Many of these are airborne and there is nothing we can do to keep them out of our tanks.) Keeping fish stress free and the water clean is our best - and our fish's best - defense.

Cathy

I can't answer your question but I'm sorry to hear about your beautiful gourami rsanz... I hope he recovers.