General Information and Prevention: This is the most fatal betta disease, oftentimes linked to the feeding of live foods, especially black worms. Little is know about it,
but what causes the raised scales is fluid building up under the skin, inside the betta's tissue. Usually what causes fluid to build up is simple kidney failure. And as you know, once the kidneys fail, the body dies. Although dropsy (the symptom) itself is not contagious, the bacteria that cause the kidney failure are contagious. Dropsy is practically untreatable and almost always fatal.
Symptoms: There are two tell-tale signs of dropsy: raised scales (meaning they move away from the body) and a bloated belly. Every once in a while I hear a case of raised scales that seems to resemble dropsy but the fish is fine afterwards, leading me to think that he didn't actually have dropsy.
Treatment: No cure is known for dropsy. Isolate your betta if he is in a community tank or in a bowl with a divider (he shouldn't be in the first place) so that the other fish don't come down with dropsy. There is little you can do for him, unfortunately, except keep his water clean. As the disease progresses, you will probably notice that Mr. Betta will seem to be in pain. If you can, it is humane at this point to euthanize him. Read more about euthanization and humane ways to do it in the last half of the Diseases page.