What causes bumps on goldfish?

a fish that is swimming in a tank.

Many clients call our office with concerns about “bumps on goldfish.” Most of these growths are benign cutaneous tumors within the layers of the fish’s skin. (Technically nerve sheath tumors aka neurofibromas or shwannomas.) It is very common to have goldfish with a few lumps, bumps, nodules or growths; whatever you want to call it.

Are bumps on goldfish life threatening?

These growths are not of concern to the overall health of the fish. They do not cause any quality of life issues other than aesthetic ones.

Is there treatment for bumps on goldfish?

Sometimes, these growths can get very large, and due to resistance from a swimming fish, fall off and grow back. They tend to be highly infiltrative into the skin, so surgical excision is only a temporary fix. We have attempted to apply cryotherapy to several cases, with good temporary, but not long-term, resolution.

Bumps on goldfish

Mario, the goldfish pictured above, had multiple growths on his body and fins. This image was taken a few weeks after cryotherapy. The attachment of the growth caused the top portion of his tail to require regrowth, but you can see the lumps are not truly gone.

So, these lumps on your goldfish are really nothing to worry about. There is the potential for them to become abraded and require topical care, and they may fall off and grow back, but your fish’s quality of life will not be affected. If you are concerned about bumps on goldfish, contact your local aquatic veterinarian through the American Association of Fish Veterinarians or the World Aquatic Veterinary Medical Association.

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21 thoughts on “What causes bumps on goldfish?”

  1. Hi, thank you for the above information. My comet has a slightly different lump forming on his neck appearing from under his scales. It’s sort of appeared in the last day and is actually pretty big for a day’s growth. It looks like it is surfacing to burst. I’ve not experienced anything
    like it on my fish and it seems different to what you’ve described above. Is this lump treatable? Could this affect other fish in the tank?

  2. My goldfish is in a 55 with 2 other goldfish he had a few little bumps on him so I was freaking out until I saw this. I thought it was a fungal infection so I was doing 50 percent water changes. My goldfish is fine now but scared me because I’ve had him since I was 10 that I got at a carnival but he is fine now luckily.

    1. a woman in a lab coat smiling for the camera.
      Dr. Jessie Sanders

      These lumps will typically fall off and grow back. They are usually not life threatening, but you can get it checked by a vet if you are concerned.

  3. Amanda Jane Paryag

    Im so worried my fancy cold water goldfish both hav and they started on the side if body now one has a hige head but still loves food.thank god I hav them in a 70 l bio my fish before
    I cant bare this as my other fish had for 18÷ and I killed them by puttin in 105 bio didn’t wait but buried in .I hate this help please 🙏

  4. My goldfish started getting this bump on his right side and top fin since 2018. It started out small, but now it’s getting bigger by the minute and it’s slowly starting to penetrate his other side. It sometimes peals, but I’m worried it’s getting to him because I find him laying on the ground sometimes. Is this an infectious parasite? If it is, should I call a doctor to have it surgically removed? I love my fish extremely and I don’t want him to die. 🙏🏽🐟❤️

  5. My gold fish is a couple of years old in a 55 gallon tank with two other gold fish. He developed a bump on his back quite early on and it never seemed to bother or harm him. Just recently, he started to turn from completely orange to fully white. At the same time, the bump on his back has completely gone away and is the only place on him that still has a faint orange area. This transformation probably happened in the matter of two weeks. I have no clue what is going on.

    1. It’s great to see that you are concerned for another living creature. I was just worried that these tumors would be contagious. I’m glad I didn’t have to cull Lumpy from the pond school

  6. My beloved goldfish has te same red/purple bump growing on him, it has trippled in size the last 2 weeks.. i am pretty worried about this because the other fish keep biting it.. the fish is acting normal and happy since i put the lil biters in a seperate tank.. the red bump looks exactly like the one on mario, the fish in the picture.. due to financial problems it wil take months before i can afford a vet to have a look at it.. i have the fish for over 12years and i dont wanna lose my lil buddy

  7. yes a goldfish in my office aquarium also has lump near his tail and it is growing but the fish is eating good and looks healthy and happy … was bit concern for him ,but after reading the information shared by you feel better . thank you

  8. Pingback: How to handle Goldfish Tumours and Growths? - TheAnimalsPedia

  9. Hi! Thanks for this super-useful article!

    You mention that lumps are normally nerve sheath tumors, but what about carp pox (herpes) or other viral infections that can cause growths on goldfish?

    Other sources have stated that they’re fairly common too and can become a problem if growing on the eyes, gills etc.

    I’d love to hear your expert opinions! Thanks!


    1. a woman in a lab coat smiling for the camera.
      Dr. Jessie Sanders

      Excellent question. I reached out to Dr. Thomas Waltzek for clarification. He is a highly respected aquatic virologist. Here is his reply, “Historically, CyHV1 was thought to have a very wide host range among various cyprinids (carp, goldish, ide, and others) and many non-cyprinid species. However, solid evidence that CyHV1 causes proliferative skin lesion in species other than common carp is minimal. There are recent papers in a few other carp species (not goldfish if memory serves). Over the years many folks claim goldfish are affected by CyHV1 based on lesions similar to what is observed with carp pox in koi and common carp. In some cases I think it has been confused with fibromas in goldfish. I am not aware of solid molecular evidence of CyHV1 in goldfish. However, we designed good PCR assays for detecting CyHV1.”

  10. John Christopher

    I have 3 fantail gold fish and one got boils/bump/lump on her tail(I don’t know what to say it looks like boils to me). This lil one was laying eggs last week and this week I could see 4 boils on her tails. Sometimes she is sitting in one corner. Is this a big concern ? Will other fishes also gets affected ? Do I have to do anything?

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