There is a genetic problem that effect fish in that way, they always look as if they have dropsy, but most dont the scales sticking out all over thier flanks, its because their growth is stunted they grow outwards instead of length ways, they never reach full size but most live a long life in a normal pond enviroment, even breed with normal fry emerging, if this is the case for your fish theres nothing to do, if it was dropsy the fish would have died a long time ago, so its seems more likely your fish has the genetic disorder.

Another known cause is a fish kept in a small tank or bowl for several years then put in a pond, the effect is like your fish too, again theres nothing you can do about it.

agree with what has been said by ajc but seen nasty worm infestations? could a fish live that long with an interior worm? i,m not sure? back to you allen - just a thought hope you dont mind o/

One of my goldfish has been like this for a very long time as well. I kept looking to see if it's scales stood out, but no, so I guess it is the same as yours Roslin. It has been like it for a good 4 years or so. It is a large fish anyway in both directions !! and is fit and healthy. Thanks for the information Alan, I didn't know that about them.
Alison

I wouldnt have thought so Jo, it would take a lot to make a fish swell like that and the fish would have certainly died long before two years,

thx for that guess it will live to a ripe old age then? good news all round jo o/

We too have a number of swollen goldfish in our pond. Sometimes the swelling is symmetrical and sometimes it only affects one side of the fish, causing it to look a bit bent. It affects large and small fish alike. One white fish is so swollen, it looks like a golf ball with fins! It has been growing steadily for at least a year. My husband suggested it might be a parasite and that I should treat the water, but I don't want to medicate the pond unnecessarily as we have newts, frogs and snails too and I don't know what effect this would have on them. Has anyone got any advice?

I would say you definitely have a problem and need to treat, but I'm not a fish expert so can't advise further.
IT could also be a problem with your water eg nitrate levels etc.
Is are they pregnant?

While you are waiting for another reply, do an internet search for pond+goldfish+ your symptom eg bloated or swollen or diseases.

I toke my fish that is swollen like a pinecone to the pet store.I was told that my friend of 10 years had gloat and would more then likely die.I was giveing a # to a fish expert and he said it was dropsy he told me to salt my water and to feed my fish english peas frozen so you can take the outer skin off.I cant say it works yet I just started treatment two days ago but ill let yall know.