Can I treat this goldfish’s tumour?
My 25-year-old goldfish has developed a lump or tumour under the skin close to the gill, and I think it is affecting the use of that gill.
The bulge developed and formed very quickly and although I have attempted to treat the condition with an antibacterial remedy, it has not improved. Please can you offer any advice on what I might be able do to?
DOMINIC THOMAS
PETER ADVISES:
Twenty-five years is a really good age for a goldfish, but as fish get older, they are also more likely to develop cell abnormalities that can develop into tumours. You mention that the lump has developed very quickly. In the case of fish tumours, these generally develop slowly over weeks or months, although some types of tumour have a more rapid growth. If the lump on your goldfish has developed from an undetectable size to that shown in your pictures within just a couple of weeks, it could possibly be due to something else, notably an internal bacterial infection.
From the images, it looks like your fish has some small brown spots on its skin. Are they part of the fish’s normal pigmentation, or have they appeared only recently, along with the lump? I mention this because the sudden appearance of numerous small brown patches on the skin can be a sign of septicaemia, which is indicative of a severe bacterial infection involving the blood. If the lump is a bacterial infection, then unfortunately over-the-counter anti-bacterials aren’t always effective, and an antibiotic would be needed. That would entail taking the fish to a vet, ideally one who has a specialism or particular interest in fish.
However, assuming your fish isn’t rapidly deteriorating in health—and from the images it appears to be in an otherwise okay condition— then I’m not convinced it’s a bacterial problem. In an ideal world, we would have a sample of the lump surgically removed and examined by a fish pathology lab to determine whether it really is a tumour, or something else.
But let’s assume it’s a rapidly developing tumour. Many fish tumours are benign, and a fish may survive many years with them. In general, they are not infectious to other fish. We see a lot of benign superficial skin tumours, such as fibromas, on goldfish. However, the tumour on your fish appears to be bulging from under the skin and, as you have mentioned, it could physically encroach on the gill area and compromise respiration.
There are currently no reliable treatments for tumours in fish. So, if a tumour is causing significant harm to a fish, then we may have to consider euthanasia. One of the warning indicators would be rapid breathing. Measure and compare the gill beat rate of the affected fish with that of its tankmates—is it breathing much faster? Also, look for surface-gasping and gulping, loss of appetite or sudden onset of lethargy. If you see any of these warning signs in the affected fish, then euthanasia might be the kindest option, especially given that we are now fairly sure that fish can feel pain, and certainly can experience stress.