Thyroid Tumor in Goldfish - Treatment

I have a gold fish that seems to have a thyroid tumor. It is rear of its right gill. It is more swollen then it is a lump.

Today I have noticed what looks like a small white pimple at the top of this swelling. I've had fish in the past that have had ick, so I don't think it is ick.

How can this tumor be treated. I've been told that iodized salt in a hospital tank is the treatment.

The fish is about 1 year old and in good health outside of this problem. Tank water is good, I test every 4 days or so and his tank mate is a common Pleco.

Thanks for anything you can tell me.

Grant's Reply


I am assuming the lump is located below the gill as thyroid glands in carp are in the subpharyngeal region, i.e. in the chin area.

If the lump or swelling is behind the gill, it is not related to the thyroid glands.

The small white pimple on top of the swelling is unlikely to be Ich, it will be related to the swelling.

Also, fish of this age seldom develop tumors.

Internal ailments are very hard to treat. The safest method is to boost the immune system of the fish by feeding high quality food, preferably some live, keeping the water quality pristine, and putting the fish in a bath of UN-iodized plain cooking or aquarium salt.

Put the fish into a salt bath of 0.3% solution (1 tablespoon per gallon, 3-4 grams per litre). Add 1/3rd immediately, 1/3rd in 8 hours, and the last 3rd 8 hours later.

It shouldn’t, but if the fish starts to keel over on its side, halve the dose. Goldfish can take a lot of salt generally, up to triple this amount.

Leave your fish in the treatment until you see an obvious improvement.

This treatment will remedy 90% of external Goldfish illnesses, and help with internal problems by treating any secondary opportunistic pathogens.

Don't expose the Pleco to any salt as they have low tolerance to it.

As an aside, Plecos and Bristle Nose catfish often develop a taste for the protein in the protective slime on Goldfish.

They wait until nightfall and attack the fish while they are sleeping.

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Oct 09, 2020
Gold fish with thyroid tumor- reply to Grant
by: Anonymous

Grant, The gold fish passed away last week. There was a lot of bleeding under it's skin. It was swimming fine and then took a nose dive to the bottom of the tank and was dead. I have know idea as to what happened. Main reason for this message is to tell you THANK YOU very much for your in put and taking the time to help me out. Your a good man for doing so.

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