it could just be a sore... you might want to try an anti fungal or even a parasite cure on him. you can pick those up at any walmart or pet store. your best bet would be to take the fish into a petstore and see what they think.

goodluck

-Kris

Not a pet store, I would recommend if you are going to take him to be diagnosed, do it at a fish store. I would call first, maybe talk to the owner or manager of fish store to see if they can help you or guide you to where you can go. Did you look at the link web site I posted for you, on the pond forum, to check for symptons? Good luck,
Theresa

Hi Theresa & Kris
Yes I have looked at that site and several others. It would seem that whatever it is does not fit any description/pictures I found. I think I'd probably need to do a scrape or take it to the vet. Already asked local vet about it and he said any testing would be very expensive $150 & up--not worth it for a $15 fish. Actually he may be worth more than that as is 8" long (measured against glass).
Did find an excellent goldfish site that has real pictures on real fish! Goldfishparadise.com. Also has a forum with various sections.
Fish has now been in quarantine for 8 days, tank temp is 78, .2% salt and melafix. Lump looks a little smaller but not much. Will continue to treat for next week and if no change get the temp back down and put him back with his buddies. Will keep you posted. Thanks for your help. Jalal