Koi Health Info

Koi are often aptly named "living jewels" because of their exquisite markings and patterns. They are lovable aquatic animals, each with its own personality and quirks. However, because of usually high stocking densities in often barren ponds, koi keeping can be demanding. The hobby has flourished in the past few decades, creating one of the most unique and interesting niches in the world. Each year, thousands of ponds are constructed in backyards. Koi keeping in itself is an art form; use this website to expand your knowledge. A degree of skill and expertise is required to maintain optimum conditions and prevent diseases. 

Koi require good water quality. The water must be tested often with a water testing kit which you can purchase from our accessories tab..

They need an adequate filtration system and lots of aeration. "Look after the water and the fish will look after themselves." That just about sums up just how important water quality is to fish health. Indeed, unless conditions are right, fish health problems, disease and fish losses will follow as sure as night follows day. Koi's oxygen requirement is generally believed to be a concentration of around 6 parts per million (PPM) of oxygen in the water. In 1959, A. Krogh, in his "The Comparative Physiology of Respiratory Mechanisms", showed that a 200 gram Koi requires 100 millilitres of oxygen per kilogram per hour. His tests on a 70,000 gram man showed we require 200 millilitres of oxygen per kilogram per hour at rest, which jumps to 4,000 ml/kg/hr at maximum work levels.

So.... Koi need a lot of oxygen!! Almost as much as we do when resting!!!

Ammonia and Nitrite should always be tested at 0. If the test reads above this level, a 20% water change should be carried out every other day until the levels reach 0 again. The reason for Ammonia and Nitrite levels rising must be discovered ASAP. Just a few suggestions that could be put forward as the reason for this issue could be because of overfeeding, because filter system is immature - (on new ponds), filtration inadequate, decomposing fallen leaves or debris on pond floor or overstocking.

We are often asked about 'SAFE' stocking levels. This really depends on so many factors - not least of all the skill and experience of the pond-keeper! However, it is important to realise that as stocking levels increase, the safety margin between good and poor health and conditions decreases. As densities increase, so does the need for constant water-testing, health monitoring and system maintenance. It is these considerations along with initial pond and filter design that really determine how many fish you can keep. As a very general guide, a safe (ish) stocking level would be around 8-12ft of fish per 1000 gallons (UK 4,500 litres) - assuming adequate filtration etc. Once you go over this level you start to move into "intensive" stocking levels! Here are a few basic pointers of which you should be checking regularly. 

Daily Tasks

1. Feed - frequency depends on time of year.

2. Check all aeration, UV and filter systems to ensure all are functioning.

3. Check all koi for signs of behavioural change or physical damage.

Weekly Tasks

1. Check skimmer functioning and empty waste basket, this should be done more regularly in Autumn.

2. On both pump and gravity fed systems, any mechanical filter media such as brushes or foam should be cleaned at least once a week to allow good flow of water through the filter.

3. Test your water.

4. Any Koi that show physical damage or infections will require topical treatment and should be netted and treated at least once a week. In some cases you will need to treat twice a week until enough improvement is seen, then you can reduce treatment frequency.

Monthly Tasks

1. Between Autumn and Winter any aeration to the pond should be decreased to limit the effect of water chilling by reducing the amount of cold air which can defuse in to the pond. Also turn down or off any waterfalls or fountains for the same reason.

2. When spring returns and starts to move in to summer you should re-commence these as well as the air pumps to increase oxygen levels in the pond as the water temperature starts to rise.

3. Check and clean filters as required.

Yearly Tasks

1. Change your UV in spring.

Essentials for Koi keeping are as follows...... nets, a well balanced Koi feed, salt (to administer salt baths) Water Testing Kit. One of the most useful pieces of koi keeping equipment you will ever need is a Koi first aid kit. Koi can suffer from a whole range of health problems and diseases including hypoxia, gas bubble disease, dropsy and general lumps and bumps. Being prepared for such health issues can often be the difference between life and death. More often than not, a primary health problem, which is easily treatable, develops in to a more serious secondary issue that can cause loss of your Koi. You can put together your own little Koi first aid kit....you will need Iodine, scissors, tweezers, hydrogen peroxide 3% solution, malachite green, cotton buds, Koi sedation, top sealer, Orahesive powder, towels, top sealer, kitchen roll and microscope for parasite detection.

Dropsy

With this disease, the fish's body swells up, the eyes bulge out and some or all of the scales may stand out from the body, making your Koi reassemble a pine cone. This disease is serious and often there is no way back. Antibiotics should be administered in case the problem is bacterial. If there are no signs of improvement after the course of antibiotics, the kindest thing you can do is to put your Koi to sleep.

Lumps, bumps and scrapes

Koi seem to develop bumps and scrapes overnight! The causes can be the result of many different factors. Firstly you need to work out whether the lump is on the skin surface or underneath. Under the skin lumps can indicate the beginning of a bacterial infection or tumor either way you should seek the advice of your specialist aquatic vet asap.

Carp pox

Carp pox is a common complaint. It appears as waxy like growths anywhere on the Koi's body. Usually it affects the fins. Carp pox is a herpes virus. A lot like cold sores, Carp Pox never goes away, it just hides for a while but it will go away with warm water temps. With most viral infections there is a risk of recurrence.

Flashing

Flashing is a common cause of bumps and scrapes. The term flashing is used when the Koi flicks its body against the sides of your pond. This is a sign that the Koi is irritated. This could be because of high Ammonia and Nitrite levels or perhaps a parasite attack. If you do see any odd behaviour or flashing the first thing to check is your water, test ammonia, nitrite, nitrate and ph. If all is ok do a 15% water change and leave them for a day, if something is still troubling them a skin scrape is needed to check for parasite.

How to take a skin scrape

1. Catch the koi and put it in a bowl

2. Get the Koi against the side of the bowl, raise the koi out the water against the side of the bowl so the area you want to scrape is above the water level.

3. Take a blunt instrument (wooden spatula or plastic card) and run it from head to tail along the Koi in the area which you want to take the sample from, never go tail to head.

4. When you have collected some mucus you can then transfer the collected mucus onto a microscope slide ready for examination and put your koi back in the pond, always scrap about 4-6 fish.

Parasites

White Spot                                                                           

To eradicate white spot we recommend using Malachite green & Formalin (Formalin can not be used if there is salt in the water your treating) A second dose will need to be applied five days later, and you should take another skin scrapes three days later to ensure the White spot has been eradicated.

Costia

Costia is extremely small a magnification of 100 times is the minimum required to identify costia, 300 to 400 times is ideal. Costia is a very fast moving parasite and looks in shape similar to a comma and is one of the deadliest, smallest parasites that affect koi. A treatment of Malachite green & Formalin should wipe them out in one, a scrape 5 days later will confirm this.   

Gill Flukes                                                                                                                          

Treat with Fluke-M, apply the second dose after five days and take further skin scrapes to ensure all parasites have been eradicated.

Skin flukes

Treat with Fluke-M, one treatment should be enough to eradicate them, re-scrape 7 days after treatment to confirm they have been eradicated.

Chilodonella

Like costia chilodonella are microscopic and hard to spot under a microscope, symptoms are similar to those caused by costia. One treatment should be enough to eradicate them, re-scrape 7 days after treatment to confirm they have been eradicated.

Trichodina

Trichodina, is often seen spinning and moving very quickly when viewed through the microscope, a Treatment of Potassium Permanganate should be enough to eradicate them, re-scrape 7 days after treatment to confirm they have been eradicated.

Hypoxiaget

Hypoxia is lack of dissolved gases. You will find that your fish are gasping for air and congregate around the point of water entering the pond where oxygen is forced from splashing. You can test the water for dissolved oxygen to make sure its at the correct level. If your aerating plants aren't doing the job then adding a couple of air stones to your pond should correct the problem. 

Gas bubble disease

This is the opposite problem to hypoxia. It is caused by too many dissolved gases. You will notice air bubbles in the eyes, gills and sometimes in the skin. Again you can test the water to make sure the dissolved gases are at a safe level.

Fin rot

Fin rot can start from a number of thing the number one cause is stress.

How to treat fin rot.

1. Sedate your Koi.

2. Get a sterile pair of scissors and cut a few mil behind the infected area, you may need to cut the bone if the fins badly infected.

3. Spray the area with Roccal wound cleaner dab of firmly with kitchen roll. 

4. Apply Anti-bacterial spray (iodine) to the fin and wipe clean.

5. Cover the edge of the fin with malachite green.

6. Then apply Orahesive powder over the malachite green blow, of the excess.

7. Now spray with a top coat sealer.

This treatment should only need doing two or three times and after 4-6 weeks the fin should have grown back.

Ulcers

Ulcers can develop from something as minor as a scrape. An ulcer will form when a secondary bacterial infection has infected a cut, sore or scrape. These can be avoided by giving any Koi with a visible abrasion a salt bath until the area no longer looks red or inflamed. If you don't manage to catch the infection early and an ulcer does develop, adding salt to the pond will help de-stress your koi whilst undergoing treatment. 300gm per 100litres will be sufficient. Only add salt to the pond if you really need to. Once the Koi is better you will need to do a 10% water change every week until you have changed 100% of the water as salt is not degradable and has to be removed manually. 

To treat the ulcer you must firstly sedate your Koi. I use Kusuri Koi Sedate. Mix in a bowl 10ml of sedate per 9 litres of pond water, give it a good stir and make sure you have a net to go over the top of your bowl in case the Koi tries to jump out. It’s essential you have a working air stone in your sedation mix so the Koi is still receiving enough oxygen. After a couple of minutes your Koi will float on its side, when this happens you can take your Koi out the sedate solution. Place Koi on wet towel and cover over the Koi's eyes with part of the towel (this will help to keep it calm) then begin treatment.

1. Spray all the infected area with Roccal wound cleaner dab of firmly with kitchen roll. 

2.Check for dead scales around the wound they will feel like you are touching fine sand paper or if you run the back of the tweezers across them they will feel rough, these are infected scales and need to be removed with your tweezers. It is very important that you remove all infected scales because they will continue to infect healthy scales.

3. Take a cotton bud that has been soaked in hydrogen peroxide 3% solution and start to dab over the infected area be careful not to get any onto healthy scales, wait a few moments for the infected area to foam up this is the best part, it is now killing all the bacteria that is in the wound and making it lovely and clean. Be careful when wiping the foam from the wound wipe from the outer edge to the centre with clean kitchen roll to ensure you do not get any onto healthy scales. 

4. Now you can apply Anti-bacterial (i use iodine) with a cotton bud gently massaging into the wound.

5. Wipe off the Anti-bacterial then cover wound with malachite green then a liberal amount of Orahesive powder blow of the excess you will see that the wound looks sealed

6. Now apply the Top coat sealer. The combination of the two sealers gives the medication a longer time to soak into the wound.

Place into an aerated quarantine tank wait for the fish to recover then release. I hold my Koi with its face in the line of the air bubbles from the air stone, the Koi will come round quicker, this can still take about 5 minutes. The fish will start to try to swim away, just let it go but face away from tank sides so it doesn’t bump itself. Add ½ oz of salt per gallon. Add 5% pond Melafix at the rate of 25ml per 100 gallons, per day this has excellent anti bacterial properties and helps to promote tissue growth, bring the temperature up to 24c. When doing 25% weekly water changes in your quarantine tank, continue to use the melafix and maintain the salt level @ ½ oz per gallon. 

Depending on the severity of the wound this treatment needs to be administered three times every other day. Within four to five days you will start to see an improvement in your fish. In ten days the wound will be sealed do not be tempted at this stage to return the fish to the pond, give the fish at least two more weeks in quarantine. This gives the fish immune system more time to recover and the scar tissue will get stronger. If you do not have a quarantine tank place back into pond over an air stone wait for fish to recover and then release.

Viewing a pond and its koi can be very easy on the eye and restful to the mind. It’s no wonder the Japanese value it so highly. It invites you to take a few minutes out to just sit and watch while your thoughts drift away, before you know it your day dreaming in to a pool of colour and grace then you snap back to reality to find you have been sat for over half an hour!

Seeing a koi that is in your care thrive and become more beautiful as it matures, is undoubtedly one of the greatest joys of koi keeping. Just give it a try. Watching your koi as it develops is certain to draw you further and further into the world of koi.

My personal favourite time with our Koi is at feeding times. Watching our Koi come to the surface, all their vibrant colours mixing, the graceful traits of these magnificent creatures especially the ones that prefer to be hand fed (usually the Chagoi) makes the trial and error of learning to keep Koi all worthwhile. They grow old with you and often live to approx 45 years. It isn't unheard of for them to live up to 75 years and there are even tales of them living up to 200 years old. Koi are magical to keep, it is a fantastic and skilled hobby that is so easily turned in to an obsession.

DISCLAIMER

The information on Koi treatments provided on this page lists different ways and means your veterinarian may use to treat your Koi. This should never be used to treat Koi by anyone other than a qualified individual. This can be used to give an insight of what to expect from your vet and to make you more aware of signs of poor health. Always contact your vet or Koi specialist if any of the diseases/infections we have highlighted occur.