Originally Posted by Chris.
Thanks for the link! What do you think of this disease? What is it and how can I treat it? My dwarf gourami has a similar problem but much worse than the one in the picture. He is alive, but doesn't do much. one side looks like the picture, but the other side has a deeper hole eaten through.
These ulcers are probably due to a bacterial infection of some kind. The fish in picture seems to have a swollen belly ("ascites"), which is another symptom of MB (mycobacteriosis).
You can try salt baths and antibiotics for the possibility that the disease is not MB, and therefore, treatable.
If these measures work, count yourself lucky. Otherwise, I would either remove or euthanize the afflicted fish. Whatever bacterial infections these fish have will probably infect other fish in the tank.
I recommend a quarantine tank, rigorous culling, and a UV sterilizing filter.
I wish that adding new fish to tanks was easier for hobbyists. However, the fact is that some fish being sold are chronic disease carriers. OR the fish are so stressed when you buy them that they quickly succumb to bacteria that ordinarily are not pathogenic. Or the fish have not yet developed immunity to the natural normal flora (bacteria and parasites) in their new home. Or the new tank conditions are substandard and stress the fish. Tricky, very tricky.