Dissolve some Epsom salt in a cup and slowly add it to his water (I add 1tsp per gallon, it helps with the swelling) and change his water every day. ): Also construct a tiny black paper box with some holes in it for air and place it over his tank. Sick fish prefer dark places, it will make him considerably less stressed out. Also, keep him warm and be very gentle with handling him (when I was treating my friend's fish Ryuk with Dropsy, I'd turn off the lights in my room so it was pretty dark when I did water changes).
If you want to try and treat him, you can try Maracyn-two, tetracycline or if you can find Kanacyn. I've heard of a few successful treatments with Kanacyn. And also, if he still can eat, try and find some antibiotic food.
And most importantly, even though some people argue that dropsy is not contagious, DON'T share equipment with other fish. Unless you know 100% what cause the dropsy, it could be a internal bacterial infection that caused it and you don't want to spread that contagious bacteria around.
): You'll also probably have to throw out anything that touched him afterward because it's too risky using it again even if you try and clean it (even bleaching which will kill almost all bacteria, does not always destroy everything).
Finally, if or when he passes away, DO NOT FLUSH HIM. Just because whatever he had could contribute to polluting the water. Burying him may have the same effect, or if an animal digs him up and eats him, the animal could get sick as well. But the safest thing to do would probably be to cremate him, but I don't know the process for that. So it may sound horrible, but it may be best to seal him in a ziplock and throw him in the garbage.
Last edited by BakaMandy; 11-02-2009 at 01:21 PM.