I've got a female goldfish who is at least nine years old. She has just started moving and eating again after the winter and I've noticed that she isn't symmetrical anymore. One side bulges a little bit - enough to make the scales over that area stick out from her sides a little. As far as I can make out from reading around this is like dropsy. Doesn't dropsy affect the whole fish though? Also, I've read that poor water quality is often the cause but I tested a week ago and the ammonia and nitrites were both 0 ppm. I didn't check the nitrates but I will do now. In the meantime is there anything else it could be? What course of action do you recommend? All the other fish including lasts years youngsters seem absolutely fine. I don't want to lose her!

Thanks.

Place in a hospital tank with a tonic salt, this will minimise osmostic stress on the fish. If the kidney can not regulate the normal level of fliud in the body then dropsy can increase to the whole fish.

Dropsy can be caused by many things, virus, bacteria or physiological disfunction, however, usually its bacterial.
Treat with some anti-internal bacteria and try to raise the water temp to 20oC

Thanks D.R.. I haven't got a hospital tank big enough for her but I'll see if I can make something. How long should she be in it do you think? Or is it until her scales are back to normal?

I would keep it isolated until the dropsy has subsided, do not feed during this time. Dropsy can be difficult to treat at times, but fingers crossed.