Identification of Koi parasites.
Most koi parasites are not visible to the naked eye. In order to correctly identify any koi parasites you will need a microscope with built in light and a magnification of 400 times.
These are simple to use and are an essential piece of kit for any koi keeper.
To accurately detect any koi parasite causing an infestation of your koi, you will need to take a skin scrape. This involves using a microscope slide to carefully remove a small quantity of mucus from one of your koi. The mucus is then sandwiched between the slide and a cover slip and inspected through the microscope. We would recommend that upon purchasing your microscope, you ask your koi dealer to demonstrate this technique to you. This will help avoid causing any possible damage to your koi.
If you suspect you have a koi parasite problem, skin scrapes need only be taken from two or three koi, if parasites are found, it is safe to assume all koi are infested by the parasite and therefore the entire pond will require treatment.
Before any parasite treatment is used in your koi pond, it is vital that you know the exact volume of water and temperature, and that adequate filtration and aeration is provided. Parasite treatments will lower the dissolved oxygen levels in the pond so we recommend adding additional aeration when using any chemicals in your koi pond. You must also switch off any ultra violet sterilisers / clarifiers and ozone equipment.
Caused by Ichthyopthirius multifiliis. The white spots on the skin, gills and fins are individual protozoan cells that are under the skin and feed on the body fluids and cells. They then punch out of the skin and fall to the bottom of the pond, collect together and begin breeding, the offspring then re-invest the fish.
As well as white spots symptoms are scratching and swimming into the water inlet, failure to feed and lethargy. It is fatal if untreated. Fortunately commercial white spot remedies are widely available.
Classed as a large protozoan parasite, white spot must initially be detected through the use of a microscope, however if left, its effects becomes identifiable with the naked eye. Koi infected by white spot appear to be covered in white spots the size of salt grains, where the parasite has burrowed through the outer skin layer.
To multiply the adult parasite leaves the host koi, it then forms a capsule around itself. Within the capsule it divides and multiplies producing up to 1000 tomites (babies). These are then released as free swimming parasites to go in search of a new host koi.
This reproductive cycle is rapid and so early detection of this koi parasite is essential.
To effectively eradicate this koi parasite we recommend using a treatment which is a mix of formaldehyde and malachite green. Pre-mix solutions are available, but it is better to mix your own as the dose rate of formaldehyde should be altered dependant upon pond water temperature.
Trichodina is one of the easiest protozoan parasites to detect under the microscope as it is almost perfectly round with hundreds of hooks which resemble cilia found its periphery and it constantly rotates as it moves through the mucus, causing tissues damage.
It attacks both skin and gill tissues of our Koi, and can often cause more damage to gills than realized.
Classed as a warm water parasite, it can survive for some time without a host. It causes vegetation of the skin giving rise to a grey white opaque appearance on the body of infected Koi which exhibit the classic symptoms of flashing, rubbing and lethargy.
Trichodina is another small protozoan parasite which is commonly found on koi. Microscope identification is necessary, as it has an average size of 0.07mm in diameter.
This parasite is circular in appearance, and is often seen spinning and moving very quickly when viewed through the microscope. The parasite attaches to the koi using tiny hooks and holding discs.
The koi parasite Trichodina can quickly cause severe damage to the skin of a koi (as can all parasites) leaving the koi open to secondary infection from bacteria such as Aeromonas. Trichodina can swim well and therefore this koi parasite can quickly infest an entire pond of koi, especially when the stocking level of koi is high. Trichodina multiplies by division.
A magnification of 100 to 200 x is required to view this parasite.
Recommended treatments are Potassium Permanganate.
Trichodina Video Clip 1 Trichodina Video Clip 2
Gill and Skin flukes are two of the family of monogenetic trematode genera, all of which are characterised by the large grappling hooks which are used to attach themselves to their victims.
Affected Koi often exhibit classic signs of irritation and flash, jump or rub themselves against objects in the pond in an attempt to rid themselves of their attackers.
Flukes are not visible with the naked eye. When viewed under a microscope, the parasites are clearly visible as nearly transparent and worm like, and the hooks are clearly visible.
This koi parasite reproduces live young. Being hermaphrodites, all of the adults are capable of producing young, and each one will carry a single larval parasite in its abdomen. Further more, this unborn parasite is also developing a larval parasite in its abdomen before they are even born, and in as little as one day after being born, those young can also give birth. So it’s easy to see that this koi parasite is very prolific, and one individual is capable of reproducing into thousands in a short period of time. When viewing this parasite under a microscope you can often see 3 or 4 developing parasites within each other.
Once this parasite is attached to a host koi, it lives and feeds on the mucus skin and blood of the koi. The parasite is capable of surviving without a host koi for five days.
This koi parasite can be treated using Kusuri Fluke M.
Dactylogyrus (gill fluke)
This koi parasite is very similar to Gyrodactylus in appearance. It has a set of hooks with which to attach itself to the host koi and these are surrounded by a number of smaller hooks.
The two parasites differ however in their method of reproduction, this koi parasite is an egg layer, and can lay up to two- dozen eggs per hour. Water temperature is important as the reproductive rate increases in warmer water, and decreases in colder water. The same applies to the time required for the eggs to hatch. In warmer water hatching can take only four days, whilst in colder water it may take as long as thirty days. This is a very important fact to remember when treating this koi parasite as most treatments will not kill the eggs, and they can hatch even after treatment and re-infect the fish. For this reason either the initial treatment has to stay active for at least four days, or you must do a second dose of the treatment.
To treat koi infested with this parasite you will need to use Kusuri Fluke M, take further skin scrapes to ensure all parasites have been eradicated.
Dactylogyrus Video Clip 1 Dactylogyrus Video Clip 2
Ichthyobodo necator (Costia)
This koi parasite is extreamly small (10-20 microns long) and a magnification of 100 times is the absolute minimum required to identify costia, 400 times is ideal. When taking a skin scrape and looking for Costia, try to avoid using a thick layer of mucus and add a drop or two of water to the slide. Costia is a very fast moving parasite and looks in shape similar to a comma, search the entire slide carefully but you will often find it easiest to identify this parasite along the edge of the mucus layer where this meets water.
Costia affects both the skin and gills of koi, and left undetected will multiply at an alarming rate and can soon cause mortalities of koi.
Symptoms of infection include excess mucus production, respiratory distress, and general debilitation, the eyes of your koi may also appear sunken.
The koi parasite Costia has a very simple life cycle, using a process known as binary fission, meaning each parasite divides into two.
Costia infestations can be treated using a mixture of Malachite Green and Formaldehyde at the same dose rate as described above for white spot. Another effective treatment is potassium permanganate
Costia is a minute Flagellate with 3-4 flagella. It affects both the skin and gills of Koi, and reproduces itself by binary fission. Infestations of this parasite can appear very rapidly indeed, and Koi suffering infestations exhibit the classic symptoms of lethargy, clamped fins, rubbing and flashing and the skin can take on a grey white opaqueness.
Costia normally only affects fish that have already been debilitated by some other cause, and can often be seen on Koi as a secondary parasite.
Remember a high magnification must be used to view these parasites (400 x) and staining is recommended for positive identification.
Costia Video Clip
Chilodonella is another protozoan parasite which effects the skin and gills of koi.
This koi parasite is typically between 40 and 70 microns in length and is oval in shape. Again, identification of this parasite can only be achieved through the use of a microscope.
The parasite multiplies quickly through division, although from time to time a pairing of two individuals takes place where some genetic material is exchanged, this process is known as conjugation.
As this koi parasite is an efficient swimmer, infection from koi to koi can also spread quickly, especially in overstocked ponds.
Effective treatment of this koi parasite can again be achieved through the use of Malachite green and formaldehyde mixed together, at the same dose rate as for White spot and Costia. In many cases, one dose is enough, however further skin scrapes should always be taken and secondary doses applied if required.
This koi parasite is most commonly found on newly imported koi, and should be dealt with by your koi dealer, it is rarely a problem for the koi hobbyist. It is visible to the naked eye and the adult parasite may reach 12mm in length, with anchor like appendages at the head. It attaches to the koi and the anchor penetrates under the scale and into the muscle of the fish, where it feeds. This parasite reproduces by laying eggs, two egg sacs are produced at the end of the females body, the larvae hatch from these egg sacs and swim freely until they come into contact with a koi, they then commence the cycle again.
Crustacean parasite, Lernaea - Anchor worm is a common parasite on our Koi which is clearly visible to the naked eye. The parasite burrows its head into the Koi's tissue, under a scale and only the body and tail are normally visible.
The juvenile stages settle in the gills of Koi, when they mature they mate and the male leaves the Koi, the fertilized female settles on the body of the Koi and continues to grow, becoming the familiar worm shape.
The female buries into the skin and underlying tissue to hold on. The damage caused can become a target for bacterial or fungal infection which can spread.
Lernaea lay eggs which can lay undetected in the pond and can hatch when conditions and water temperatures are right.
The parasite can cause serious damage to the koi where it penetrates the tissue. These wounds sometimes heal very slowly and if untreated become infected with bacteria and fungus, it is these secondary infections that cause the most risk to the koi.
To treat Anchor Worm you must treat the pond to sterilize the adults, this treatment should be repeated after seven days to ensure any eggs that were unhatched at the first treatment are now sterilized after hatching. Now all reproduction has been stopped. The treatment used is Dimilin.
Now the adults must all be removed from the koi. To do this you will need to sedate each koi individually and carefully remove the parasite with tweezers, making sure you remove the entire thing including the anchor part. Each entry wound should then topically treated. Check every koi in the pond to ensure none are missed.
Treatment is by manual removal of the parasite with tweezers under anesthetic, ensuring that the whole parasite is removed. To be sure of complete removal, dip a cotton bud in strong potassium permanganate solution and dab the worm with this solution whereupon it will release its grip immediately. Pond treatments include Dimilin or Paradex.
Argulus another crustacean parasite, round and up to 1cm wide. They have a sucker to hold on to the Koi with needle-like mouth parts which they stick into the Koi and inject a toxin. This causes intense irritation to the Koi and they scratch and jump and can cause bacterial infection. The punctured areas of the koi will also be open to secondary bacterial infection.
This parasite can be introduced to the koi pond by visiting frogs and toads.
Argulus reproduce by laying eggs. After mating the female detaches from the host koi to deposit her fertilized eggs on the pond walls or any other surface. Upto 500 eggs may be laid. Dependent on water temperature the eggs take between two and four weeks to hatch. The newly hatched parasites will swim to find a host koi. They will reach sexual maturity after 20 to 50 days depending again on the water temperature of the pond, then the cycle starts again.
To treat an Argulus outbreak you will need to sedate and inspect every koi in the pond, removing all adult parasites with tweezers. The pond must then be treated to kill off the juveniles. This treatment should be repeated two or three times at intervals of seven to ten days. The most effective treatment is Masoten.
Raised scales (rather like a pine cone) and eyes standing out from the head.
Dropsy itself is not a disease, but rather a result of some other cause. Dropsy is a term given to the swelling that occurs internally in the fish. There are multiple possible causes. Sometimes it's not contageous, but sick fish should be isolated and treated since determining the actual cause may be impossible, and also because this will be easier on the fish.
The fish's body will become swelled with fluid it is unable to expel. Eventually the swelling will cause the scales to raise, giving the fish what is called the "pine-cone" appearance.
Diagnosis, One of these situations may be the cause:
- Sudden swelling: A bacterial infection will cause internal bleeding.
- Slow swelling: Growing tumors, or even parasites, in the fish may cause it to swell.
- Slow swelling: Mycobacterium tuberculosis. Highly contageous!
Bacterial dropsy is infectious so treat with an anti bacterial remedy and if possible isolate affected Koi.
The bacteria are most likely to infect fish that have been stressed by such conditions as poor water quality, inadequate diet, or handling and shipping. Columnaris can enter the fish through the gills, mouth, or via small wounds on the skin. The disease is highly contagious and may be spread through contaminated nets, specimen containers, and even food.
Treatment with anti bacterial medicine is usually effective.
A number of bacteria are associated with finrot, lesions and internal hemorrhaging, notably Aeromonas and Pseudomonas. Ulcers usually start at the site of an injury, the bacteria then infect it causing further damage, and fungal infection can also occur.
Such holes result in osmoregulatory problems, leading to damaged kidneys and death if not treated. It is worth adding a weak salt solution to the pond as well as anti bacterial remedy, a concentration of 0.3% or 1/2 once per gallon of salt will help to restore the osmotic balance and reduce strain on the kidneys (make sure that the salt is fully dissolved before you add it to the pond).
Finrot is easily noticeable, the fins and/or tail look chewed and are red at the edges. Secondary bacterial and fungal infections can develop.
Gill maggots are the mature females of the parasitic crustacean Ergasilus.
Ergasilus (gill maggots) will appear as grayish black and white parasites several millimeters long infesting the gills.
Heavy infestations can cause severe damage, eroding the gill filaments and allowing secondary infections to develop.
One of the most common fungal infections of Koi. The fungal spores will grow anywhere on the Koi, including the gills, initially germinating on dead tissue. Their threadlike hyphae release digestive juices which break down the tissue so the fungus can absorb it, as the fungus grows these juices start breaking down living tissue.
Fungus on the body appears as cotton wool like growths, it is hard to tell if a Koi has it in the gills, but if it hangs at the surface gulping for air it is likely.
Carp pox. A virus that produces solid waxy lumps on Koi. It will not kill Koi and is generally harmless, but can look unsightly. It is most often present in small Koi and in cold weather, clearing up disappearing when Koi grow and in the spring when water temperatures rise.