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Goldfish Diseases,
Symptoms and Possible Cures

There is a huge range of Goldfish Diseases and Goldfish illnesses such as parasites and infections. These effects are usually increased by overcrowding and not sufficient aquarium care. We will highlight here a few of the diseases particularly relevant to the goldfish. While most can be prevented, it can occur in even the best kept tanks.


FUNGUS Goldfish diseases

This is caused by (Achyla and Saprolegnia) and is a common disease to aquarium fishes, but usually only effect fish that are already in a poor condition (the reason for this is not clear). The spores that give rise to this infection are quite common in water, and can only get access to the skin of fishes that's been damaged by rough handling, fighting or attack by other parasites.

When not treated the white/grey cotton wool-like fungal can increase and spread all over the body. This goldfish diseases will eventually kill the fish if not treated with a fungus remedy. Always first try to treat the fish by adding medication to the water. As a last resort in very bad cases you can dip the fish into a strong solution of the fungal treatment, avoiding dipping the eyes also.


This disease is related to the presence of large numbers of parasites on the fishes skin and gills like Costia, Ichtyobodo, Chilodonella, and Gyrodactylus, or a combination of them. In some cases Ichthyophthirius (Ich) may also be present. It will irritate the skin of the fish, causing excess mucus production - hence the name of the disease.

Affected fishes will become agitated and rub against the gravel or decorations in their tank. Other symptoms may include spotty red areas on the body, closed fins and increased gill movements. Sliminess of the skin can cause death of the fish, or can weaken the fish in such a way that it is acceptable to other disease organisms. It can be treated at the appropriate time with a white-spot remedy or a broad spectrum anti-parasite medication.

FIN or Tail rot

Fin or tail rot is usually the result of a local bacterial infection which can be brought on by a number of factors, including overcrowding, unhygienic tank conditions and if the water temperature conditions is too low.

You will recognize these goldfish diseases by the appearance of split and torn fins, and may be streaked with blood and/or show reddening at the fin bases. Like all the diseases quick treatment is very important and a number of brands of general fish tonics are effective against Fin rot. Both Fin rot and fungus infections require immediate attention and is a good indication of unsatisfactory aquarium conditions.

TOP: Symptoms of Fin rot and Mouth Fungus

MOUTH FUNGUS (Cotton-wool disease)

Mouth Fungus are Goldfish diseases caused by the bacterium Flexibacter, and often occurs with new fishes or those who are kept in unhygienic conditions. Mouth fungus disease can destroy the mouth and that’s why quick treatment is essential and vital. It may respond to a treatment of proprietary remedies from a aquarium shop, but in more difficult cases it is advisable to be treated by adding antibiotics to the water.

WHITE-SPOT also called "Ich"(Ichthyophthirius miltifiliis)

This Goldfish diseases is transmitted by a protozoan parasite and is transferred directly from fish to fish, and therefore it can quickly build up in a well-stocked aquarium. It is very easy to diagnose the disease, as it appears as white dots or spots on the skin, gills and fins. It typically looks like white sugar grains.

Heavily infected fishes will scrape themselves against rocks and other decorations in the tank. White-spot is usually introduced into aquariums with new fishes, live foods or new plants. We suggest that you quarantine all new fish and plants for two to three weeks with a proper treatment of white spot remedy. A good product range are now freely available on the market and white-spot can be treated very effectively.

TOP: Ich or also called White-spot, clearly visible


This is one of the Goldfish diseases that are often caused by a systematic bacterial infection. This spreads through the body of the fish and manifests itself as ulcers, reddened areas on the skin, raised boils and reddening at the fin bases and the vent. Loss of appetite, tiredness and listless behavior is some of the other symptoms.

This Goldfish diseases can be brought on by incorrect care, and recently spawned fish as well as new fish. When they show signs of the disease they should be isolated from other fish. You can treat them by feeding them antibiotic medicated flaked food, or by adding some antibiotics to the water. Once the symptoms decrease and the fish start behaving normal, it can be returned to the aquarium.

TOP: Clear signs of Ulcer disease, a bacterial infection


This is a rather uncommon parasite and Goldfish diseases, but can be a serious problem if not treated. Not only do they feed on the blood and tissue fluids of a fish, but they can also transmit certain diseases between fish, leaving it acceptable to secondary invasion of fungus and other bacteria.

Not all leeches are parasites. When you see parasitic leeches on your fish, make sure you take speedy action before the leeches build up in numbers. Because of their powerful suckers it can’t be easily removed.

You can remove the serious infected fish to a treatment bath containing a three percent solution of cooking salt and water (30gram salt per liter of water / 24 level teaspoons salt per gallon of water). Leave the fish for about ten minutes in the solution. Those leeches which do not fall of the fish can be removed with tongs.

The leeches you removed with the tongs can be killed by throwing in hot water. Some anti-parasite medication may prove effective against leeches.

TOP: LEECHES are parasites feeding on the hosts blood and body tissues.

FISH LICE (Argulus sp.)

Fish lice are another type of large fish disease that an aquarist can easily diagnose. These disc shaped crustacean parasite can be found on the skin and fins of the infected fish and is about 0.5cm (0.2inch)in size. The lice can move about on the body of the fish and also away from the host for short periods of time.

With their piercing and sucking mouth parts they can irritate their host to such extremes, that heavily infested individuals, will often jump out of the water to get rid of the lice. These lice also transmit different microbial diseases, and the wounds left by their mouth parts can get invaded by fungus. It’s quite easy to treat by using broad spectrum anti-parasite medicines.


Especially newly acquired fish sometimes have this relative of Argulus (fish lice) found on them. Hanging from the flanks, head area or fin bases of the fish like small tubes 1-2cm (0.4-0.8in) long, it is relatively easy to spot.

Heavy infestation will debilitate the host and signs are a reddened boil-like lesion developing at the point of attachment. The best way of treatment is to remove the parasites with a pair of tweezers. Hold the fish in a damp cloth when doing this. Disinfect the aquarium afterwards with a suitable remedy available from your pet shop.

FISH POX Goldfish diseases

Although this disease mainly affects Koi fish it also seems to be found less frequently in goldfish and other species. A white, light pink and also sometimes a greyish waxy growth on the skin and fins are symptoms of this. The growth tends to appear, develop and then disappear again.

The growth is caused by a viral infection in the cells of the fish’s body. It seems that fish pox is not very infectious and don’t pass between fish. This is about all known so far about this disease and is more unsightly than dangerous to the fish. No reliable treatment is available so far and the fish keeper must learn to accept it for the time being.

DROPSY (Pinecone disease)

This Goldfish diseases is commonly confused with kidney bloat but caused usually by bacteria Pseudonomas or Aeromonas. The bacteria profoundly attack the fish’s kidneys. There is a distinct difference apart from that it also causes swelling of the abdomen and is combined with 100% scale protruding over the body and bulging of the eyes.

This is usually an untreatable disease and best be destroying the fish painlessly as soon as possible.

TOP: Dropsy - Protruding scales, swollen belly and bulging eyes as one of the Goldfish diseases

KIDNEY BLOAT (Mitraspora cyprini)Goldfish diseases

Another parasite infection known as Kidney bloat (that’s where the kidneys are swelling and the belly of the fish becomes grossly distended) is infectious and can’t be treated. Kidney bloat and a tumor are easily confused, because both are showing growths, either on one side or both sides of the fish.

Investigate the scales of the fish to see if 100% of the scales are protruding from the body. If this is the case, it’s most likely not a tumour or kidney bloat but probably Dropsy.

That’s why it’s wise to isolate these fish from the other when you see this kind of symptoms. So long as the fish is feeding and behave normally, keep it in isolation and look for signs of improvement. But if it looks like the fish is suffering you can rather destroy it painlessly.

TOP: Kidney bloat caused by Mitraspora as one of the Goldfish diseases

VELVET DISEASE (oodinium or O.pillularis)

This disease is very similar to Ich in its life cycle. Symptoms is a golden velvety coating usually first seen on the back of the fish. It gradually spreads over the whole body of the fish. This is a very small yellowish parasite not easy to detect. The best medication to use is Acriflavine and obtainable from your fish shop.


SWIM BLADDER DISORDER Goldfish illnesses

The infected fish can easily be recognized by the fishes position in the tank. It either floats to the surface or sinks to the bottom of the tank. Hasty changes in temperature are often cited as a cause of the swim bladder disorders. The Fancy goldfish seem mostly prone to the problem, and this may be related to the deformed swim bladder shape of them.

The condition does not appear to be infectious. There is no cure for this. Some relief can be offered to the fish by keeping the fish in shallow water and at a few degrees warmer than the aquarium water. Fish showing Swim bladder disorder should not be used for breeding, and those that are no longer able to feed should be destroyed painlessly.

POP-EYE (Exophthalmia)Goldfish diseases

It’s pertinent for a condition in which one or both eyes stick out (protrude)from the head of the fish. (You must note that certain fancy varieties of gold fish are purposely bred to have protruding eyes.) The problem is rarely infectious and causes the fish very little discomfort. There is no reliable treatment and along as the fish feed and behave normally, there is no need to take any action.

GROWTHS or TUMORS as Goldfish illnesses

They appear as obvious lumps on the outside of the body or as hard swelling among the internal organs. External tumors can be removed surgically by your veterinarian, but the treatment of an internal growth is basically impossible. This is usually not infectious.

TOP: Skin tumors are Goldfish illnesses uncommon and can usually be removed surgically by a veterinarian

IMPORTANT NOTE: Although we give here some explanation of Goldfish diseases and Goldfish illnesses and how to resolve or cure them, we would recommend on getting expert advise from a veterinarian if the problems persist. This should not be necessary if good care is taken in maintaining your tanks.

For a Expert diagnosis and recommendations, ask our vet's.

Return to Fresh Water Aquarium Fish from Goldfish Diseases

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Read all about correct Goldfish Feeding

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