As some of you know I have a fantail goldfish named Nugget. I have had him for over 3 years now, however for the first couple of years (when I knew nothing about gf) he lived with 3 other gf in an overcrowded tank and I did not take the proper care of him that I now know that gf need. Although he somehow managed to survive (he outlived quite a few tankmates) he is now stunted (he has only a 2 inch body, with a 3+ inch tail and large eyes for his body size). He acts fine though, plays with his tankmate, eats well. etc .

Now for the problem. Over the past year or more he has developed a lump which is definitely under his scales (as opposed to at the surface). It has been growing very slowly and as it grows it seems to be pushing out the scales slightly in this area (causing them to appear more raised and white in color). There has never been any redness or pus at all - it just looks like a hard, irregularly shaped mass. It is difficult to see unless you are at the right angle and I have not been able to get a good picture.

I have assumed it was a tumor or else an internal reaction to a bad case of anchor worm he had many years ago (I think there was one in this area). He has been exposed to nearly every med imaginable (both maracyns, parasite clear, prazi, fungus clear, salt, medigold, metromed) over the past year or so and nothing has helped. The mass is right behind his gill region so I am hesitant to try anything topical.

I guess I am just bearing my soul and asking if anyone knows if there is anything more I might try (I feel so guilty). For now, he seems fine but as it gets bigger and bigger I worry what the future holds .

Thanks much

As requested, the tank info is below:

Ammonia Level? 0
Nitrite Level? 0
Nitrate level? 10
Ph Level, (If possible,KH and GH and chloramines)? 7.8
Ph Level out of the Tap? 8.4 ( I use crushed coral to buffer the tank and only do 25% changes at a time).
Tank size (How many Gals) and How long has it been running? 3+ year, 16 gal
What is the name and size of the filter/s? marineland filter, biowheel, extra bubble wand
How often do you change the water and how much? 25% 3x/week
How many fish in the tank and their size? 2 fantails, ~2 inch ea
What kind of water additives or conditioners? Prime
Any medications added to the tank? None now
Add any new fish to the tank? a couple weeks ago to replace Freckles who died after a long bout of sbd
What do you feed your fish? Progold, spirulina, anacharis, etc.
Any unusual findings on the fish such as "grains of salt",
bloody streaks, frayed fins or fungus? No, just the chronic lump described above
Any unusual behavior like staying at the bottom, not eating, ect..? No

Hi Sea it's good to hear from you.
The first thing that I want to say is that goldfish do get tumors/benign/cancerous lumps,etc. I am not thinking that this is bacterial, as Nugget has had it now over a year or more.Anything bacterial would have probably reared its ugly head a long time ago. I've read about these tumors of sorts,and it seems like some fish can live quite a long time with them and not be much affected by it. We know that Nugget is stunted,we know that he's been through many different med treatments.What we don't know is,Was this lump caused by some infectious agent,or was it a result of some side aide effects from previous meds used on him,or lastly,was it in his genetics to begin with?
I think at this point,as long as he seems to be eating/swimming normal/faring well,I'd leave it alone.IMO,meds out there today will get rid of a bacterial caused lump,but I don't think they'd do anything for this sort of growth myself. I am course,am far from the expert here,so someone else may have a different opinion or experience on it. I think anyway,that as long as the lump doesn't suddenly change,grow red,or grow over his gill plate,or seem to start causing any other problems,that it may just sort of lay idle,if you know what I mean.
If it were me,I'd make sure to continue to keep his params spot on ,especially because you have 2 in a 16 gallon tank,and I'd also continue to enjoy Nugget as he seems fine for now. We can't say what will happen down the road,but you can't continue to worry about the future,or you'll make yourself
I know this may not be much of an answer,but it's the only thing that I could say,as I have never experienced this myself.

Thanks for your kind answer, Devs . I didn't really think there was much I could do now since the damage was already done but thought I should ask just in case. It actually helped me just to write it all out as I still feel really guilty about the conditions he lived in during his first year here which resulted in his being stunted. He is such a happy trooper though and really loves his new tankmate (still no pixs and no name, my bad).

My first goldfish, bubbles, had something similar. I kept him in a 1 gal bowl for the first month I had him and was afraid that I had stunted him too. After that I moved him to a 20 gal with another small fancy. After a while I realized that bubbles was not growing whereas my other fish was. Bubbles developed lumps in the shape of his body where occasionally they would open and there would be a white sore. It would heal itself and then another one would break open. Bubbles lived for a few months with those symptoms and then seemed to have died peacefully at about one year old.

He was the best fish. My feeling was that the problem was genetic, as I can not convince myself (completely) that just a month when he was small could have stunted him. He did not look like other fancy goldfish and never really grew any scales.

There is my sad story. I wish you well with Nugget, you must be taking very good care of him and I am sure he appreciates it.

Thanks for sharing your story, Carole. I like your point of view and will try to focus on how much I learned and how well I care for my guys now instead of what's past .

Hi Sea, sorry to hear about your fish, it does sound a bit like a tumour. As Sharon said, you're slightly overstocked, but you are doing pretty regular water changes so as long as you keep that up it's the best you can do. If you've tried every medication under the sun and nothing makes it go away, then as Sharon said, it's better to leave him alone, as long as the fish is still happy and taking food. Adding more meds will only stress the little guy and his tank mate, there's not much you can do for fish tumours. Give him the nicest life you can offer him. And remember, in the future, if he does succumb to the tumour, you have done everything there is possible to help the little guy.