Home Problems & Solutions Can Fish Have Cancer? (Yes.. Here’s the Healing Guide)

Can Fish Have Cancer? (Yes.. Here’s the Healing Guide)

by gvald

We know the sometimes disastrous effects of ultraviolet rays (UV) for humans and some mammals (dogs, cats…) when they lead to the appearance of melanomas, we now discover that fish can suffer from the same ills.


If you are on this page, you probably wondered if fish can also have cancer, and yes, unfortunately it is the case, and many have already contracted it.


How is a fish tumor called ?

Lymphocystis is caused by a virus, of the iridoviridae (DNA virus) family. Iridoviridae affect insects, frogs, fish and mollusks. This virus forms nodules, cysts (depending on what you want to call these growths), on the skin of the fish. It is a long-lasting disease, the cysts often grow slowly. At the beginning of the infection the fish does not show any particular signs of fatigue, it can take up to 1 year before the fish becomes weak.


This virus is not highly contagious, but it is better to isolate the patient for treatment. If a nodule breaks through it can spread the virus into the aquarium water.


This disease causes an abnormal growth of skin cells. There may also be several cysts in different places on the fish’s body.


How do you remove a fish tumor?

If the tumor is large enough, it may be possible to take your fish to the veterinarian, but you should not do the operation yourself.


However, as in humans, the tumor may come back.


How do you know if a fish has cancer?

As in humans, tumors may be visible on the body of the fish. It will also not be uncommon to see abnormal lumps in internal tumors.


Lymphocystosis occurs when the lymphocyte virus is introduced into the fish. It is usually brought in through an injury, and/or poor quality water contaminated with the virus. An important stress of the fish (acclimatization, transport…) seems also to favor the development of the virus. A new fish, healthy carrier, may also have transmitted it to a weaker fish in the aquarium or pond.


This disease is more frequent in garden ponds because the water is more easily contaminated by rainwater and wild animals.


Benign tumors may bother the fish but do not kill it. However, in some cases, they can be painful. Malignant tumors, on the other hand, are fatal.


Does a fish have cancer if it has a tumor?

This is not necessarily the case, and far from it. Most cancers diagnosed in fish are skin cancers. This is still to be verified, because both diseases can be fatal for your aquatic companion.


It is more rare to see cases of skin cancer in fish in aquariums, most cases are tumors related to not clean enough water.


What to do if fish has a tumor?

There are two methods to treat this disease, but they are not foolproof. Indeed, even after a cure, the fish may relapse, several months or years later.


Treat your fish with daily baths in a hospital tank. Leave your fish 6 to 8 hours a day in a hospital tank with a treatment containing acriflavine. Buy one of the medications I recommend below and follow the instructions in the package insert for dosage.


Between baths, return the fish to its aquarium (if it is alone) or to its hospital isolation tank. Do not exceed 1 week of treatment. Normally the ball will transform and change color (green). Then disappear with time.


Note however that fishes that are big enough can be operated by a veterinarian. As in humans, the tumor can still reappear. If the fish seems to suffer from it (abnormal behaviors etc…), it may be necessary to consider euthanasia.


If your fish is in an aquarium with other fish, it is imperative to change the water and to check if the others do not have the beginning of a tumor either. However, be careful with water changes, no sudden temperature changes, this could also be fatal for your fish!


How many fish are affected by cancer?

15% of a species of fish, living in the Pacific Ocean, would be affected by skin cancer. The holes in the ozone layer could be the cause.


Unfortunately, the number of fish affected by the disease could be more important than initially estimated. This is because organisms with advanced cancer are certainly less active than their healthy counterparts or those with superficial lesions. They probably feed less and are therefore less likely to be captured since they do not attack the bait. The 15% incidence may therefore be an underestimate.

You may also like