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Koi Diagnosis and Treatment Guide

Koi Diagnosis and Treatment Guide

Your Koi rely on you to provide a healthy environment in their pond and to ensure that their lives are stress free. Many diseases and even parasites in koi usually result from the following issues:

  • High ammonia levels In the water
  • Parasites
  • Poor water quality
  • Overcrowding
  • Handling the fish
  • Stress
  • Toxic chemicals
  • Sharp edges In and around the pond
  • Inadequate or Incorrect nutrition
  • Predators, Heroin and Otters

We would recommend a basic kit to use to help identify what might be wrong with your koi this would include the following

It is essential that you identify the signs of disease or infection at the earliest opportunity and then take the appropriate steps to tackle any condition that you discover.

We would also recommend keeping some essential treatments just incase you need a solution quickly

Below are some of the most common diseases, parasites and infections you should look out for.

Parasitic Infections

Ich / White Spot 

Also known as White Spot Disease. The first symptoms of Ich are the appearance of small white parasites on your fish. These look like grains of salt. Ich is usually the result of poor water quality and you will need to address both the disease and its causes.

The symptoms of Itch are tiny white cysts on the Koi’s skin and fins, Koi often have clamped fins and  Koi may flash or itch themselves on things within the pond. The Koi’s gill movement may have increased this would then be a sign of gill irritation also the Koi may be showing signs of reduced activity levels and they may also eat less than usual or may not eat at all

To treat Ich you should first increase the salt concentration of your  at a 1/2 oz to a gallon of water over a period of a few days. The water temperature should be increased to around 26°C and aeration should be improved. Alternatively you can address Ich using Malachite Green and Formalin. Follow the dosage and administration instructions provided by the manufacturer carefully. Treat the infected fish in the quarantine tank or your pond, and continue the treatment for the recommended period of time.

Cleanliness is the key when it comes to managing an Ich outbreak. Increase the frequency of water changes to maintain optimal water quality and keep the recommended water parameter’s  It’s recommended to perform daily water changes of at least 20% during the outbreak period. Keep on top of your filter cleans as well

Chilodonella

This condition can be fatal and is caused by a leaf shaped protozoan parasite.

Chilodonella are microscopic, so you will need a  microscope to see these and preform a skin scrape. Water samples should be looked at with a water test kit  as well as skin mucus scrapings from your Koi  always scrape gently so as to not cause as little stress as possible or any further harm to the Koi.

Symptom’s of Chilodonella are, The koi may appear to have cloudy parts on there skin this is due to them producing more mucus as they try to protect themselves from the parasite. The Koi may be flashing or rubbing on things within the pond like the bottom drain, pump or the walls of the pond  this will be to relive there selves from itching or any discomfort they may be in. They may be gasping for air at the ponds surface and they may be off there food or not eat all. your Koi may also be lethargic and appear to not be moving very much

Treatments:

A mixture of malachite green and formalin have been shown to be the most effective against Chilodonella.

You could use Potassium permanganate which is a chemical but you do need to follow the manufactures instructions on the packet properly  It’s highly oxidative, breaking down living tissues. When dosed appropriately, this does not harm fish or plants, but will break down the tissues and cells of parasites, bacteria and fungi.

Please ensure that you read and understand and follow, all Health and Safety guidelines on the packet.

Anchor Worm

Anchor worm is also known as Lernea and is a crustacean parasite which is clearly visible to the naked eye. This parasite burrows its head into the Koi’s tissue, under a scale and only the body and tail are normally visible.

The parasite can cause damage and infection to the koi where it penetrates the tissue. These wounds sometimes heal very slowly and if not treated quickly and effectively can become infected with bacteria and fungus, it is these secondary infections that cause the most risk to the koi

Treatment for Anchor worm is to remove the parasite with some tweezers making sure the whole worm is removed this will need to be done while the Koi is sedated with koi sedate  

To be sure the complete removal dip a cotton bud in to a strong potassium permanganate solution the Anchor worm will then release its grip immediately, enabling you to remove it and dispose of carefully

Flukes

There are two types of Flukes koi can get the first one is a Skin Fluke ( Gyodactylus) and the second one is Gill Flukes (Dactylogyrus) both are microscopic and will need to be identified using a mucus scrape and a microscope

Both skin and gill fluke have grappling hocks which attach to the koi and are egg layers and live bearers

Symptom’s of Flukes:

The main symptoms of flukes are  irritation, Flashing or rubbing there selves on things within the pond like your bottom drain pump or sides of the pond, Koi may be jumping, You may notice the Koi moving its gills more than normal and they may swimming erratically you may also see the Koi flicking or twitching there fins

Treatment:

If you have Koi afflicted by flukes Gill or skin then the entire pond could be affected and must be treated with one of the following treatments. Lernex – Lernex Pro,  Kusuri Fluke S or Fluke M and NT Labs Flukasol Suspension are a few of the different Fluke treatments we stock at Cotswold Koi

Please always follow the manufactures instruction and dosage rates

Argulus/ Fish Lice

Argulus or fish lice are parasites which cause irritation to Koi this can lead to bacterial infections if not treated quickly and affectively. You will be able to see these with the naked eye the size of these varies between 1mm and 5mm, Fish lice attach themselves to the koi with sucker, they will cause damage to the skin at the attachment area and they also inject a poison into the koi which causes information and can protentional cause a secondary infection. Argulus must be treated quickly as this parasite can cause physical damage  to the koi’s skin which often results in ulceration of the infected. The irritation will cause the Koi to rub or flash themselves against objects to gain relief.

The best treatment is to physically removal the lice from the koi before a chemical treatment is done with Potassium permanganate or  NT LAB Permanganate

 

Velvet Disease

This is a condition caused by Oodinium parasites. Your koi will acquire a velvety golden dusting and may lose some of there scales. This is a rare condition which can be treated by adding Formalin to the water.

Never add  Formalin to a pond which has a salt content.

Costia

Costia are tiny parasites microscopic which reproduce rapidly. you would need to identify these with a mucus scrape and microscope

Koi generally do not suffer from Costia unless there immune system is already compromised in some way. Costia would be a secondary infection. If Koi are affected then this usually happens in the spring. Koi will seem lethargic not swimming around much and will try to rub, flick or flash against the sides of the pond. The affected areas take on a whiteish, grey cloudy hue and the Koi’s fins may be red. If the parasites effect the gills the fish may be seen gasping at the surface of the water and may move there gill excessively.

Costia can be treated by adding Malachite Green and Formalin to the pond but you must ensure that there is no salt in the water prior to treatment. You could also consider using Acriflavine. this would also be to the pond if you discover Costia you would treat the whole pond not a single fish

Never add Formalin to a pond which has a salt content.

Leeches

Leeches feed on the koi’s blood and will eventually kill the fish if left untreated. They also transmit the disease SVC (spring Viraemia of carp).The leech is a pale brownie colour about 1mm in width and can measure up to 25mm long. The leeches will be visible on the body of the koi

Treatment would be salt  it’s crucial to use salt responsibly to avoid disrupting the pond ecosystem. Using salt in a controlled way can be used to get rid of leeches without harming your Koi if administered properly. We would recommend adding  salt at a 1/2 oz to a gallon of water this can deter leeches while keeping the pond environment safe for your Koi.

In cases of leech attachment to a Koi a mild antibacterial treatment might be needed to prevent secondary infections. Remember, chemical methods should always be a last resort and used in accordance with dosage and manufacturing instructions.

Trichodynia

This is a protozoan parasite which causes Koi to display a grey/white opaque appearance to there slim coat The parasite damages the Koi’s tissues and trichodynia can effect the koi’s skin and there gills. Trichodynia will appear in a pond due to poor water quality and overcrowding with to many fish. If found in a healthy pond, they were likely introduced via a new fish that was raised in less than ideal conditions (such as an overstocked pond) They can also be interduce to a pond via a new plant that you may have just purchased.

Trichodynia is microscopic and will need to be seen under a microscope after taking a skin mucus scrape.

Symptom’s of Trichodynia Koi may appear lethargic and will rub or flash themselves on the side of the pond. Excess mucus may be noticeable. The koi may have red patches on its body and there fins, you may also notice white patches of skin this will be the attachment sights of the Trichodynia.

Trichodynia can be treated by raising salinity to 0.6%. in the pond or by giving the Koi a salt bath using 1/2 oz to a gallon of water or 14g to 4 litters of water.

You can also use Potassium Permanganate or a course of Formalin. Always follow the instruction on any treatment

Do not use salt with Potassium Permanganate or Formalin

Gill Maggot

This parasite often attacks the Koi’s gills and has a maggot like appearance. They are typically several mm long and are visible with the naked eye. The obvious sign after seeing the Gill Maggots themselves is damaged to the gills. The gills will become yellow or red and tattered looking they will also be swollen and coated in mucus than normal  you may see painful red blisters developing. The Koi may also have difficulty in breathing you may notice they have excessively more movement to the gills. Gill maggots will also causes irritation to the Koi often Koi will flash or be flicking of the sides or bottom of the pond. There may also be signs of a secondary infection

Treatment would be a salt bath at 1/2 oz to 1 gallon of water or 14g to 4 litters of water  for no more than 10 minutes then repeat for 3 consecutive days and than increase to up to 6 days if needed also increase aeration to the pond. Improving the water quality by maybe doing 10% water changes daily or 20 to 25% weekly and by providing good nutrition’s Koi food 

All these things will help get rid of Gill Maggots

Diseases

Dropsy

Dropsy is also known as Pine cone Disease, This is due to the swelling of the body due to fluid retention and is generally the result of poor water quality it can also be parasitic viral or bacterial infections. Koi suffering from Dropsy often show swelling or lifting of the scales. ( pine cone appearance) Their eyes may also bulge and they may have less swimming buoyancy. It is best to quarantine any affected koi if you can although the condition is not highly contagious. Dropsy is so difficult to cure especially in its later stages But there are things you can try.

Treatment quick identification is the key with Dropsy and will depend on the underlying cause of Dropsy it is very difficult to identify were and why it has been caused, (fungal, parasitic or bacterial ) So treatment would be to treat the fish for both Anti Parasitic and anti bacterial.  We would suggest Chloramine T  for the bacterial or Potassium Permanganate for the Bacterial and parasites and also Cytofex for external bacteria (fungal)

Tail Rot and Fin Rot

Tail rot and fin rot are secondary conditions caused from an underline condition  normally by stress, poor water quality or a bacterial infection, some times it can be caused by a fungal infection as either can compromise the immune system. bacterial infection will present there selves in an uneven pattern which looks like the fins are slowly rotting away and it will start from the edges and a fungal infection will be more even in shape and will produce a white colour along the edges of the fins and tail,  Symptom’s are fraying or rotting edges to the fins and tall, Discoloration of the fins, inflammation and missing fins, changes in behaviour like Flashing or rubbing, hiding away isolating themselves from all other fish and changes in colour to the koi it self.( look at the whites of the koi do the look pink or red)

Treatment would be Cytofex or Alparex as both will treat the cause as well as help the symptom’s

Mouth Rot

This condition causes sores in the Koi’s mouth and is often caused by poor water quality. You will need to start by doing a 30 % water change as soon as you notice mouth rot, cleaning your filter and monitoring your water parameters using a water test kit will also help.

Treatment for mouth rot, we would recommend a salt bath using 1/2 oz to a gallon of water or 14g to 4 litters of water for 5 to 10 minutes, You could also use Cytofex or Alparex .treating your whole pond and you can also treat the mouth directly with anti bac or even hydrogen peroxide using a cotton bud and dabbing a small amount on to the sore while the koi is sedated

Infections and Virus’s

Aeromonas And Pseudomonas Bacterial Infections

Aeromonas and  Pseudomonas are the most common bacteria found in all pond water. Even if you keep your pump and filter as clean as possible, there are still Aeromonas and Pseudomonas in the pond,

Aeromonas and Pseudomonas symptoms are ulcers on the koi, fin rot, mouth rot and tail rot. and koi may also have changes in there behaviour for instance your koi may be sluggish or lethargic and they may not be not feeding The can also isolate  there selves away from other koi in the pond.

If  this infection is left untreated the damage they can inflict will eventually kill the koi

Aeromonas and/or Pseudomonas exist in almost every Koi pond in the world. it is possible for Koi to be around these bacteria and NOT be infected because Koi have a defence mechanism This defence is made up of their slime coat  mucus and their immune system. both of these help to protect them against these bacteria infections.

To diagnose a pond with Aeromonas or Pseudomonas a water sample and or mucus sample  will need to be taken and sent away for analysing and a treatment plain more than likely be an antibiotic that will need to be injected in to the fish this  would also need to be prescribed by a Aquatic Vet on a prescription.

Erythrodermatitis

Erythrodermatitis is also known as Spring Viraemia, SVC, and Viraemia. it mainly happens in cooler temperatures, so in the winter through to the spring and shows as red spots on the fins of the Koi other symptoms can be  a swollen abdomen, lethargic behaviour and possibly clamped fins and be on the bottom of the pond. This virus is contagious. it is also worth noting that even if a Koi survives this virus it can still spread it to other koi.

The disease spreads through the waste of infected koi, Also Blood-sucking parasites in and around your ponds can also pass this virus on to your koi

Because there’s no specific medication or treatment for erythrodermatitis, The only thing you could try is feeding your koi a vitamin-enriched food like Medikoi Health If you able to control the water temperature within your pond by keeping it warmer you can also prevent erythrodermatitis.

A fish that survives erythrodermatitis will develop immunity against the virus.

Exophthalmos/ Pop eye

This fish disease is also know as pop eye because one or both the eyes of the Koi will pop out ( budging eyes). It’s easy to see the symptoms of exophthalmos, as it is a lot harder to pinpoint exactly how it was caused.

One reason would be water quality. If you notice exophthalmos in your Koi check the pH, ammonium, nitrate, and nitrite levels in your pond water and pond pH levels with a water test kit they should fall between 6.0 and 8.0. If they’re off, at all you will need to balance them by doing a 10% water change to start with then using the correct product to aid in lowering or increasing the reading we would recommend Microbe-lift treatments

Another reason for the cause of exophthalmos is vitamin deficiency. If your koi aren’t getting the nutrients they need, their body’s might overcompensate and cause pop eyes. Feeding them a food with added vitamins and nutrients is a very good way to solve this possibility. You also need to check and ensure your using Koi food that has been stored properly once opened and before it best before date.

You might notice that new Koi experience exophthalmos when they’re added to your pond. In this case, it usually means that they’re stressed from the change of environment.  Its worth noting that moving home for Koi can be very stressful and could be an underline cause

Koi can often make a full recovery in 7 to 10 days as they acclimate to your pond, as long as all other conditions are favourable.

If only a few koi in your pond seem affected by exophthalmos, You can conclude that it’s most likely a bacterial infection, which isn’t widespread throughout your pond right away. This gives you a chance to quarantine the infected fish and nurse them back to health in a separate tank to save your other koi.

Koi Herpesvirus/ KHV (also know as carp pox)

Carp pox, or koi pox, is an inherited gene passed down through koi and wild carp which causes outbreaks of the herpes virus Cyprinid Herpesvirus 1, or “CyHV-1”.

Although this is contagious between koi, the virus lays dormant within the carriers of the herpes gene. Usually it develops during periods of stress or lower immune activity, or when koi are still young and growing

The virus can be present in a fish which is born with the carrier gene, and will be with them throughout their entire life in varying degrees of severity.

Unlike the highly deadly herpes viruses CyHV-2 and  CyHV-3, the inherited CyHV-1 herpesvirus is not dangerous and  koi usually outgrow their symptoms as their immune system matures as they age.

“CyHV-1”. symptoms

Symptoms of the common CyHV-1 virus are mostly cosmetic causing a slight swelling almost like a spot  which is white in colour and they are hard to touch.  This usually disappear as the virus is reduced by the immune systems response. As a koi’s immune system matures with age The virus lesions and this is why some koi keepers state their Koi “out grow” the virus after reaching full adult maturity.

The common herpes virus, CyHV-1, often presents as white or pinkish waxy spots, most commonly on the fins, head and tail of the fish, it  looks similar to candle wax in appearance. They are semi-translucent waxy lumps and may look unsightly but they are typically harmless and do not need any direct treatment. These waxy spots or lumps are the single most common symptom of the CyHV-1 herpes virus. if you notice them on your koi you can safely assume you have the common carp pox virus and not the deadly CyHV-2 and  CyHV-3,  sub-type varieties and allow them to disappear on there own as the koi matures

This koi fish disease CyHV-2 and  CyHV-3, KHV  is known to be a very infectious and deadly disease, even if your pond is clean and not overcrowded and safe from predators.

The virus reproduces in cooler water and only affects koi, so if you have goldfish and other fish in your pond, they’ll likely not to be effected.

CyHV-2 and  CyHV-3,

The two dangerous herpes virus sub-types, CyHV-2 and CyHV-3  also known as KHV, attack the blood producing internal organs of the koi, the kidneys the liver and the spleen. The mortality rate of these sub-types is as high as 90%, and displays as red sores and lesions over the koi’s body creating a rash-like appearance.

There is no cure for any type of carp pox, but luckily the deadly sub-types CyHV-2 and CyHV-3  are very rare  and in almost all cases your koi will display whiteish, pink spots which are almost a definitive sign of the non-deadly herpes virus, CyHV-1.

CyHV-2 and CyHV-3 KHV virus the dangerous herpes spreads from contact with an infected koi or from the fluids they secrete. Even mud and the water, and other surfaces that come in contact with infected carriers can transmit this disease.

KHV is a rapid killer, with death happening as quickly as 24 to 48 hours from onset. To catch herpesvirus as it starts you need to keep an eye on your koi when the water temperature is in the 50 to 80℉ range. (10c to 26c)

First, you will notice changes in their mucous membranes, which leads to severe gill decay. The gill decay makes the koi struggle for air, so we’re likely to see them at the surface of the pond, gasping for breath. Their eyes might also sink into their head as well.

Even if a koi survives herpes virus, they will still stay infectious for the rest of their lives. Therefore, the only viable solution to prevent spreading KHV is to eliminate the entire population of koi that could have the infection.

it is always a good idea to quarantine any new koi before adding them to your own pond.as well

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Identifying Bacterial Infection in Koi Fish

The signs that your Koi are sick aren’t always obvious and easy to identify. look for small changes in their behaviour, like:

  • Isolating there selves, staying away from other fish in the pond
  • Not coming to the surface for food at feeding times
  • Lethargic not swimming or moving much maybe just lead on the bottom often with clamped fins( holding  there fins tight into there body)

Noticing these behaviours in a Koi means you can quarantine the affected Koi so the disease won’t spread through your entire pond. Keeping the infected Koi in a smaller, controlled tank will give them the chance to heal and recover.

If the infections progress you will see visual  symptoms that will help you to identify the disease or infection, it is at that point you will be able to research the possible treatments that are available.

Depending on the type of bacterial infection you might see symptoms like:

  • red streaks or lines that appear on the fins
  • ragged fins and fin rot
  • Ulcers  and red sores on the body
  • white spots on the body

You can also check the koi’s mouth  for mouth fungus or mouth rot have a look at the koi’s eyes do they appear to have cloudy eyes, or bulging eyes. Look over their bodies for signs of fungus, ulcers, or leeches. These visible signs might show you that a virus is harming the fish internally, but they can also weaken the koi and make them more liable to an infection.

You can swab open wounds on your koi and send the specimen to a lab for a diagnosis. After you get the results back, You will be able to take them to a aquatic veterinarian for an antibiotic. you can also tack a mucus scrape from a koi this will allow you to see if there are any microscopic parasites on your koi you can then  identify what parasites your koi’s has and treat with the appropriate treatment

Treating and Preventing Bacterial Infection in Koi Fish

Keep your pond clean and safe to keep your Koi healthy is so important

Treating Koi Fish Disease’s

If you notice that your Koi seems to be sick or is behaving differently then you will need to  investigate why and treat the illness as soon as you possibly can. This will boost your koi’s health and ensure their safety. Feeding your koi probiotic food is a safe way to boost their immune systems whether you see signs of infection or not.

Always make sure you know what is plaguing our Koi before you start trying any thing to cure them. If for instance you think your water parameters are the reason and say you begin adding treatments for high PH levels or water temperatures with out actually knowing what the cause is  You could cause more harm than good always do a water test first .

Never treat unless you know what you are treating for

When just one or several fish seem sick, you can quarantine them in a large tank or pop up bowl  temporarily, If most of the fish in our pond seem ill, it’s best to treat the whole pond all at once.

Approved treatments for bacterial infection in koi fish include:

Treatment can be very effective but should always be your last resort when you have sick koi. Prevention is far more effective and is easily achievable It’s also healthier for the Koi as well as our ponds.

Preventing Koi Fish Diseases

A stressed Koi is more likely to fall ill and be more prone to infection disease and to parasites

  • keeping the water temperature even as much as possible Koi don’t like massive fluctuations in the water temperature
  • preventing  predator attacks from otters and heron which can cause serous injury to Koi
  • giving koi safe places to hide like some plants
  • not overcrowding the pond with to many fish
  • preventing water from being contaminated
  • looking after your water parameters taking regular water tests and improving and levels that are not right as quickly as possible
  • keeping a close eye on your Koi taking time daily to check they are ok observing there behaviour and acting on anything you might find quickly
  • Staying on top of your pond maintenance with regular filter cleans and water changes is vital
  • not over feed your Koi

Prevention isn’t difficult if you stay on top of  your pond maintenance and follow safe practices. Each pond differs depending on its location as well as the fish and plants you might have in your ponds. but if  you can do all the above regularly you and you fish should be pretty safe.

Safely Introducing New Koi Fish

Take care when your adding new koi to your pond. You must not introduce new koi if your worried that one of your original koi is maybe battling an infection or parasite.

Before you add new fish if possible quarantine them for at least 30 days. Keep them in a large tank or separate pond that’s far enough from your main pond where water won’t splash between the two. Always make sure any quarantine tank or pond has enough oxygen with a simple air pump and air stone at the very least,  you should also have some sort of filter on a quarantine tank or pond as well so to be able to keep the tank or pond clean and safe for the Koi

Always take the acclimation process slowly so the koi adapts to the water temperature and then the overall setting of your pond. This is called aqua mating ( floating the bag the new koi comes in on top of your pond water or quarantine tank or pond itself) This reduces the stress they’d feel otherwise and allows them to slowly get used to any water temperature differences which will keeps them healthy and prevents their immune system from getting compromised.

Even after you have added new koi into your pond you still need to keep a close eye on them. you need to keep an eye on them to make sure that they are adjusting well. If you notice any signs that could indicate that they may have a infection or a parasite you can then quickly address this using the above guidelines

We have included a link below to a great book that we sell and would recommended, this book will be able to help you with al sorts of Koi health problems and a be great asset to any koi hobbyist

The Koi Doctor

The Koi Doctor is an essential overview of all aspects of koi keeping. This guide is intended for hobbyists who care deeply about their ornamental fish. The innumerable tips in this book are indispensable for anyone who wants to keep their Koi in the best conditions possible. The Koi Doctor enlists and describes the most common problems in Koi keeping and presents simple solutions if possible.

Maarten Lammens presents information on water quality and disease in koi, in a clear and concise format without overload.

A good resource for anyone wishing to learn more about parasites and treatment of koi ponds.

Full of infographics and real photos of koi and garden pond treatments.

The Koi Doctor (Maarten Lammens) – Cotswold Koi

If we can help with any of the above at Cotswold Koi please do get in touch

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