Question
I have a very fat, bloated goldfish who can no longer stay the right way up.  I pretty sure it's not dropsy as the scales are not lifting like a pine cone.  It still trys to swim and has been like it for quite some time.  At first we thought it may be full of eggs but when nothing happened, it just got bigger, we've started to become concerned.  As it's not able to right itself it can't get under the water so we're worried about cold spells.  Also, is it maybe something contagious and therefore needs to be removed?
Many thanks and regards
Louise

Answer
I'm sorry about your goldfish.  I've had a few goldfish also become super fat and not have the raised scales.  When fish become slowly fat and seem to live like that for a long time, I tend to think it's a kidney malfuction.  Basically, the kidneys can't pump out the water from the body as normal.  Enlargement could also be due to a tumor but that's usually in one location and not all over.  In some cases, it could be fish tuberculosis.  

I do not think you have to remove the fish.  Most likely, it's not contagious (kidney failure and most tumors aren't).  If it is, for example with fish tuberculosis, the other fish would already be carriers of it.  That bacteria can be dormant in fish for years and then cause cheese-like growths inside the fish.  If, after the fish dies, you cut it open, you might get a better idea of what it was.  If it's just like a bowl full of jelly (like my goldfish was), then it is something like a kidney problem.  If it's white and cheesy, then that's bacteria.  If it's hard and gray, it may be a tumor.  And, so on.

This page has some photos of such enlarged fish:
http://www.fishpondinfo.com/fishcare/bigphoto.htm

Unfortunately, your bloated goldfish is most likely not going to improve.  Adding pond salt at 0.05% will help the fish some to regulate the water flow out.  Antibiotics may provide limited help depending on the cause.

Good luck!