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.
It is critical that these masses are evaluated to ensure they are not different cancerous growths, such as chromatophoromas or soft tissue tumors. Smaller bumps or lumps on goldfish may be fin ray fractures or white spot disease. If you notice anything different about your goldfish and are not sure if it is normal or not, it is best to contact your veterinarian sooner, rather than later. Many of these lumps and bumps on goldfish are benign, but some of them can be quite serious and require immediate treatment.
You may note small bumps on the leading edge of the pectoral fins in some goldfish, and if you look very closely, you may see bumps on their operculum or gill plate cover as well. These are breeding tubercules and indicate that your male goldfish is sexually mature. Sometimes, the bumps may be very pronounced, such as in the fish pictured below, or very subtle. Learn more about differentiated fish sex by external features.
Are bumps on goldfish life threatening?
Once confirmed as neurofibromas, 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. They may come and go as the fish grows, as the environment or nutrition changes, but there is no one clear cause. Most of the time, the fish don’t even notice that they are there. Sometimes, lumps near the eyes or mouth may cause temporary discomfort or difficulty eating.
Even large ones, like that pictured below, may not require treatment. As long as your fish is acting normal, swimming in in their tank or pond, interacting with all of their normal friends and eating well, treatment is not recommended.
But that bump is so large! Are you sure it doesn’t require treatment?
With this particular case above, this bump had a lot of large blood vessels associated with the mass, so removal would have been tricky and the fish may have bled out. It cannot be a fun procedure for goldfish to undergo surgical removal and we do everything we can for pain management. For these procedures that will not be completely curative and may need to be repeated at frequent intervals, we will typically not pursue treatment to avoid putting the fish repeatedly through a painful procedure.
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.
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.
Here is Mario approximately 6 months after his cryotherapy treatment for bumps on goldfish. As you can see, the masses are still very prominent, but were not causing any significant life interference, so additional treatment was not attempted.
Sometimes, if a fish is showing clinical signs to a lump, interfering with their swimming or eating, we will take steps to remove it, such as in the case of the fish pictured below. This fish was actively trying to knock this bump off his head by swimming into the decorations in his tank. With enough effort, he could have caused neurologic trauma, so the decision was made between the veterinarian and the owner to remove the lump. After surgical removal under anesthesia, silver nitrate was applied to help treat deeper layers, given the post-operative wound a gray coloration.
We have not seen this fish since, so we are unsure how his mass has progressed. We like to assume that no news is good news. Once we take care of these lumps, there is a chance it can come back, but we cannot predicate how one case will turn out compared to those we have seen in the past.
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.