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Koi Diseases & Parasites

Occassionally, even though conditions seem to be ideal, ailments will still occur. We have listed below a few of the common ailments that can be recognized and treated by the everyday Koi owner. Please take special note that delayed and/or incorrect diagnosis and/or treatment are a common cause of death so get a professional opinion if you are at all in doubt.

It is important that any new fish that are to be introduced to your pond environment be quarantined before they are introduced to ensure that the fish are free from disease and are indeed healthy. By quarantining your fish, any ailments can be treated easily and efficiently without endangering the other fish in your pond environment. It is also important that your quarantine/isolation pond/tank not be connected to the same filter system as your pond environment. Ideally only one fish should be kept per tank. A simple foam filter and air stone is all that is required. Do not introduce any live plants.

As mentioned elsewhere, knowing your Koi's actions will assist you in diagnosing and recognizing a problem early and may actually save the life of your Koi. Also a good idea is to know the Koi Clubs and Societies and Koi Professionals in your local area.

ANCHOR WORM
Anchor worms are tiny threadlike crustaceans that bury themselves under the scales of Koi, which then become parasitic. Anchor worms can greatly reduce the Koi's strength and increase the change of a secondary infection. They can be seen with the naked eye however may be overlooked as an Anchor worm. The use of a magnifying glass will help confirm that Anchor worms are present.

The treatment for Anchor worm is usually with a proprietary solution which is best recommended by your local Koi Supplier or Koi Club. Once the Anchor worms have died, the dead parasites must be removed from the fish otherwise infection may occur. You may need to repeat the treatment several times to ensure that all Anchor worms and/or larva are killed. Contamination can be caused by birds eating infected fish and then infecting another pond with its faeces, thus causing the larva/Anchor worm cycle to start again.

BLACK SPOT
Black spot appears as tiny black spots all over the body, just as the name suggests. These black spots are actualy the cysts of a fluke which lives in the intestines of various birds. The eggs of the flukes pass to the pond via the faeces where they hatch and infest snails. From here they progress to other fish within the pond burying themselves into the other layer of skin forming a black casing around themselves. As the fish within the pond enviroment are the host carriers for the flukes, they don't cause much harm to the fish. If the koi are eaten by birds, the cycle is complete and will start again.

To help prevent black spot, try to keep birds away from the pond, and remove all water snails from the pond. This will help to interrupt the life-cycle and eventually get rid of your problem of black spot. Otherwise you can purchase a commerical product from your local koi supplier or koi keeper / professional.

CARP POX
Carp pox appears in the form smooth whitish grayish waxy bumps which increase in size until they eventualy merge together. Carp pox is usally caused by dirty water conditions (unclean / insufficient filtration) and/or overcrowding within the pond and is the result of a viral infection of a dermatological nature. Carp Pox is usally not fatal and there is no known cure, however if the water conditions / overcrowding is corrected the problem will usally rectify itself over a number weeks. If the condition is left a secondary infection may occur causing further problems. Most of the time, it will go away by itself without any treatment, but do monitor the condition closely.

CLOUDY EYE Cloudy eye is a condition in which the eye appears to be cover with an opaque film. Cloudy Eye is thought to be a result of a bacterial infection and not as a result of dirty water conditions.

Treatment can include the addition of salt to the pond, which may help prevent Cloudy Eye, or by treating the koi in an anti-Bacterial bath have help with a cure.

CUTS Cuts or abrasions can be treated by painted the wound with mercurochrome or similar solution every 3-5 days until the wound has healed. Major wounds should be treated by a professional. Another alternative to treating minor cuts and abrasions is to place the injured fish into an isolation tank containing a suitable solution for the treatment of the wound. This may be as simple as adding salt to reduce the risk of infection. However, do not treat any fish without the advice of an experienced keeper.

DROPSY
Dropsy, also known as Bloater or Pinecone disease, can be recognide by the scales starting to come away from the body of the fish, similar to a pine cone opening. Fish suffering from Dropsy will have difficulty swimming, find it difficult to breathe and have a swollen abdomen. The cause of the disease is not yet understood fully and it may well be the cause of both a bacterial amd viral infection at the same time, and may actually be an infection of the kidney. The infected fish will retain liquid within body cells and the problem is linked to the blood circulatory system. In an advanced form Dropsy is usually fatal.

Due to the nature of Dropsy, infected fish must be isolated immediatley and the pond must be cleansed with the addition of salt or other treatment. The infected fish should be given a salt bath and/or one of the antibacterial treatments.

FIN ROT
Fin rot is caused by a parasitic bacteria and its is essential that it is treated promptly before the rot spreads to the body of the koi. In the inital stages fo the infection the inter-fin ray membrane becomes opaque and then starts to rot thus exposing the fin rays which then in turn begin to rot. The infection with continue to spread along the fins or tail until it reaches the body, at which in most cases the koi will most likely die. Fin rot is usally associated with fish that have had there fins badly handled or dirty water conditions (unclean or insufficient filtration).

If in the early stages of infection, it may be possible to treat the koi with one of the commerical anti-bacterial products that is avaliable on the market. However. Remember is is important to ensure that the water condition is OK before treating the pond with a antibacterial product, otherwise it will be a waste of time. If the rot is quite bad it may be possible to have a veterinarian cut away the rotted portions of the fin(s).

FUNGUS DISEASE
Fungus will appear as strans of cottonwool like filaments hanging from the koi. These strands may have a green apperance due to agal growth on the fungus. The cause of these fungal growths usally starts with fungus feeding on the small wound on the koi and eventualy spreading over more and more of the koi's body. Fungus diseases are usally associated with dirty water conditions (unclean or insufficient filtration) and/or overcrowding within the pond.

Treatment of fungal growths is with either a salt bath, malachite green or one of the many antifungal products on the market. Once the fungus has been removed from the koi the wound should then be treated as per the "Cuts" Section as listed above and the water condition or overcrowding problem rectified.

GILL & SKIN FLUKES
Flukes are rarely fatal, except to the smallest of koi. They are trematode worms (a parasitic flatworm with one or more suckers), oftern microscopic. Flukes may well live within all koi, without possing any problems. Flukes, can become a problem if the fish becomes ill or stressed at which point the flukes can multiply and create fatal situations. Gill flukes can cause the gills can become swollen, causing the koi to having problems breathing, thus gasping for air at the surface. Skin flukes affect koi in much the same fassion. Many flukes can repoduce asexually and spend there whole life within one host.

Treatment for Gill and Skin flukes is usally with a salt bath or with one of the commerical antibacterial products.

LEECHES
There are over 250 species of leeches ranging in size from small only a few millimeters to large several centimeters that can easily be seen with the human eye. Leeches attach themselves to a host an suck large quantities of blood, this debiliating (making weak) the koi. They may also be carries of blood flagellates, which are ting creatures that produce sleeping sickness in Koi, sleeping sickness will make the koi appear listless. The wounds, where the leeches have attached themselves to the koi will attract bacteria and/or fungi, thus increasing the risk of a secondary infection.

If you notice a leech on a koi, remove the koi from the pond and treat the fish in a salt bath. The leech will either fall off or it will loosen the grip of the leech, which can then be removed with a pair of tweezers. The wound should then be treated as per the Cuts Section as listed above. If the pond has a bad case of infestation it may be better to re-house the koi and clean the pond with bleach or simiular product, as the cleansing products on the market are not always that effective. Remember that plants etc in the pond may be the harboring leechs so check them throughly. Once, the pond has been drained and cleaned, refilled and allowed to stand for 5 - 10 days (with the filters running) so the whole system is cleansed throughly. When transfering the koi back to the pond take the time to inspect the koi for another other signs or ailments or diseases.

VELVET DISEASE
Velvet Disease appears as a mass of yellowish white velvety dots on the fins and body of koi. If the fish are left untreated Velvet Disease will be fatal. It is reported that this may not clear with salt, if a salt bath doesn't clear the disease then there are a number of medications avaliable, of which many have a copper sulfate base. Velvet Disease very rarely in Koi. It would be more common in freshwater aquariums or on recently purchased Goldfish. Once the mature organism falls from the fish to the floor of the pond, it devlopes a protective cyst. Within the protection of the cyst, which can be visable for several months, the organism multiples and then the cyst bursts releasing many more parasites into the pond to effect the fish. If these newly release parasites don't find a host within 24 hours they will die.

WHITE SPOT or ICH
White Spot / Ich can be seen as white spots that are dotted about the fins and body. White spot are tiny ciliates (fine haired like parastic organisms) which swim around the pond looking for a host. Once a host is found they bury themselves into the dermis where they feed the bodies cells. They they don't find a host within 24 hours they will die. After approx three weeks they fall of the host and reproduce as cysts on the bottom of the pond.

There are many commerical treatments avaliable. Some treatments attack the ciliates at the swimming stage, other treatments attack the ciliates actually on the koi. Treatments may need to be repeated. Please consult your local koi supplier or koi keeper / professional for advise on the exact treatment.

There are many other conditons / diseases that can effect koi and fish in general. These include Lice, Common Colds, Cottonwool Disease (also known as Mouth Fungus), Internal & External Tumors just to name a few. For those people that are interested in the health of your fish or just want to gain further information there are a number of good books available on the market dealing specifical with disease and aliments within Koi and various fish.

Koi Diseases