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Koi Health: The Things You Wish You Learned Before You Discovered a Problem - Play It Koi

Having your favorite pet Koi fish get sick is every pond owners worst nightmare. Let's face it, these beautiful calm creatures are like kids to some of us. What's worse is that one sick Koi left untreated, often leads to many more, and the effects on your entire pond stock can be devastating.  The old saying that an ounce of prevention is worth a pound of cure is absolutely true. I hope every Koi keeper and potential Koi keeper carefully eqiups themselves with knowledge and some basic tools before going too deep into the hobby. 

Below is an excerpt taken from one of my favorite authors KoiValley, from the Koiphen community. I think it is an excellent read and am very appreciative for his contributions and sharing of knowledge. 




The information given here is based on many year's experience; the experience of koi keepers, wholesalers, breeders and importers. In most cases you will be given some treatment options. You must do your homework, form your own opinion and do what is best for your fish in your situation. Once you have established a treatment program follow it through to the end unless it becomes obvious that a change is needed. Keep an open mind. Treatments have and will continue to change as we travel the journey of the koi kichi.

If you have not done so, it would also be helpful to establish a relationship with your local veterinarian. Doing so immediately may help in obtaining some local advice as well as antibiotics if needed.

Part One/Water Quality:

All fish have immune systems and will protect themselves when the water quality is excellent and consistent. Your pond and quarantine tank water should be tested frequently to ensure the quality of the water and thus the health of the fish.

Stability of Ph:

Test the Ph of your tap or well water. Test the Ph of your pond. Make comparisons over a few days to establish what Ph your pond water should be on average. Pond Ph may be 7.0 to 9.0 but should be stable in a range of + or - 0.3. If your pond tests at 7.5 it should maintain that level or similar to a low of 7.2 and a high of 7.8 over 24 to 48 hours.

Ph crashes are generally caused by a low level of carbonate hardness (kH). Carbonate hardness or Kh levels above 100 ppt will prevent such Ph crashes and protect the health of your fish. Kh levels of 200 are required for bead filters. kH is one of the most important water parameters to be monitored in koi keeping, but often is most overlooked. Be sure to pick yourself up a good kH test kit and this should be one of the first parameters checked if you are experiencing issues with keeping your koi healthy. API makes a good kH Test kit and this is probably the most common. You should be aiming for at least 6 drops when using this test kit. It doesn't come with their standard Master Pond Test kit, so must be purchased separately.  

Stability of carbonate hardness(Kh):

Carbonate Hardness = Total Alkalinity. Test the Kh of the tap or well water. Test the Kh of the pond. Make comparisons over a few weeks to establish your Kh average. Kh is the buffering ability of your water to hold the pH at a safe level. Kh should test no less than 100. In the event of low Kh readings baking soda works exceedingly well to maintain proper levels, and can be added without fear of harming the fish as long as done in small doses. In addition, crushed oyster shells or crushed coral can be bagged and placed in filters or in water current areas to buffer the water on a long term basis. Just remember that shells and coral are "slow-release" and a fairly large quantity must be used for any effect at all. Baking soda: See instructions below.

One further note: If you have a bead filter in your filtration system, the Kh must be a minimum of 100 ppm or more for it to function properly.

Baking soda: 2 to 3lbs per 1000 gallons will raise and stabilize Kh levels and keep the pH at 8.3 to 8.4. Raise your pH/Kh slowly over several days. Do NOT put all in at one time, do small microdoses over a period of several days to raise it. For instance, in our 6k gallon pond, when our kH is low, we will add no more than 1 cup every 12 hours until it is raised to acceptable levels. Use maintenance doses of baking soda to keep them at the desired level. Lowering kH shouldn't be necessary but if you ever need to the only way to do so safely is through water changes. 

Good water quality ensures koi health. Establish a baseline by testing your "raw or tap water". Then periodically test your pond water. In the event of a koi behavioral problem or fatality, testing is very important. In addition, water samples may need to be sent to an outside lab for further testing.

Water test kits should include Ammonia, Nitrite, Nitrate, pH, General Hardness, and Carbonate Hardness (aka. kH or total alkalinity) at a minimum. At Play It Koi, we use the following: 

Part Two/Water Tests and Associated Information

Raw water test parameters (water you use to change and/or add water to the pond):
GH-general hardness
KH-carbonate hardness or total alkalinity
City or well water? This can make a difference due to nutrient levels and chlorine additives.

Pond Water Parameters:
GH-general hardness
KH-carbonate hardness or total alkalinity
Pond temperature.

Part Three/Ideal Water Parameter Guidelines

Source water varies so make sure that you test it to give you a baseline to work with. Pond water can vary depending on the load, the filtration type and how well the pond is managed including water changes.

Here are some guidelines but your pond may not fit exactly within them. It is important to note that consistency is equal if not more important than the test "ideal levels".

PH: Between 7.2 to 8.3 but consistent and not a lot of swing.

Ammonia: The ideal is "0" but some mains water have small amounts. Less than .25% is generally considered harmless. Ammonia can cause the gills to be burned, the fins to become frayed, and the fish may begin to gasp at the surface. High ammonia levels can cause bacterial infections to develop due to stress and of course, eventually will kill the koi. It needs to be monitored closely.

If you are using a formaldehyde product to treat your koi, the ammonia reading will be slightly high as formaldehyde reads as ammonia for about 24 hours.

Nitrite: A small amount of nitrite is not dangerous, but as a filter system cycles it may become intolerable to the koi. At high nitrite levels (more than 1.5) they will develop "brown blood disease" as they will "absorb it" rather than the oxygen they need so nitrite needs to be monitored closely. I have found Pond Prime binds Nitrite and helps to "detoxify" high levels of nitrite while the filter matures and is able to digest these levels. When using Pond Prime make sure to increase aeration to much higher than might be considered normal. Salt may also be used to prevent nitrite poisoning. A rate of .15 to .3% works well.

Nitrate: "Some is always present". A trace is fine. More than that: do a water change. Nitrate is called the silent killer. It is usually not monitored very well by the average koi keeper. If the levels slowly become high due to lack of water changes it will cause ulcer disease and death. Symptoms are often called "dropsy". The most common reason for Nitrates to rise is 1) the lack of water changes 2) lack of aeration 3) or lack of pond plants. These 3 elements are the only known way to get rid of Nitrate. If your Nitrate tests high, add an aerator, add some plants, and do water changes. 

KH: Carbonate hardness/Total Alkalinity: Most water has a certain amount of buffering from the total alkalinity. 100+ppm if using bead filters. KH stabilizes(buffers) the pH and prevents any crashes. Baking soda works well for this if dosed regularly. If your hardness is 15-30 grains of hardness, or 256.5ppm to 513ppm hardness you probably will never have to worry about adding anything to supplement the stability of your pond as long as you continue to do regular water changes.

GH: General hardness is measured in grains or ppm. "0" hardness is soft water. Although there are those who might disagree, any hardness IS hard water. It's just a matter of degree. Although hardness can be altered, it can be expensive and it can reduce the overall stability of the pond. Better to monitor the GH level and refrain from trying to tinker with it. Keepers of show quality koi like to alter hardness of the water as they believe it will encourage skin quality and color. Most koi keepers just use the water they have and maintain the quality through water changes and the best filtration for their situation.

Other tests worth looking at:
Dissolved Oxygen

Part Four/Hydrogen Peroxide for algae control:

Algae control in ornamental ponds took a turn for the better with the introduction of 35% hydrogen peroxide used as an oxidizer for all types of algae. Used correctly, it safely controls algae growth giving pond owners a simple inexpensive method to use even with koi present.

35% Hydrogen peroxide is dangerous! Wear protective gloves and clothing! Wear goggles/eye protection! Touching a drop of this material will turn your skin white! It will burn! Store this chemical in a cool dry place. Read all label safety instructions! Used properly and stored safely 35% hydrogen peroxide does the job on algae.

Some guidelines:

Algae must be present. (any type of algae which you want to control)
Dosing is one cup (8 ounces) per 1000 gallons. This is a starting point. Increase dosage slightly only if algae remains present. Dosage is every three to five days. Once you have established the amount needed for your pond, then back off until the algae begins to reappear. The objective is not to eradicate it but to keep it in check.

Where streams or water fall areas need to be treated mix eight ounces (based on a 1000 gallon pond) of hydrogen peroxide with eight ounces of water. Place in a pump-up sprayer that has not been used for weed killer. Turn off the water flow and spray the areas thoroughly. Let stand for 60 minutes. Restart water.

Hydrogen peroxide is available at local pool stores. It is known as Baquacil. It is 27%. The pool people will tell you that it will kill the fish. This is true only if you overdose or treat a pond that has little if any algae.

I found that the veterinary supply stores have 35% hydrogen peroxide available in 5 gallon totes. However, it must be dispensed carefully. It will burn skin and any other living tissue it comes in contact with at full strength.

I have used and continue to use Baquacil/veterinary hydrogen peroxide with several collections of koi. I know of several hobbyists using it successfully. But these are all careful people who pay attention to the presence of algae and the proper dosage. Use this method at your own risk. Done correctly it is indeed safe for fish and produces wonderful algae-free ponds.

One further note: It is wise to obtain a Taylor hydrogen peroxide test kit. That way you can control the ppm and note if it is active for more than a day or two. If it is still active after two days make a fairly large water change to dilute it out.

I like to treat my four waterfalls with 1/2gallon hydrogen peroxide mixed with 1/2gallon water. I use a pump-up sprayer marked for this use. Once they have been thoroughly sprayed I let them stand for about an hour. Then I restart the filter and water falls pumps. After about three hours I start cleaning the skimmer brushes, the S&Gs, the Alpha One media Low Head filter, and finally the AES spherical media polisher. That way the detritus which was flushed out from the falls is collected by the skimmers and filters before I begin my weekly cleanup.

Part Five/Water changes/filtration etc:

Consistent and frequent water changes are required for nearly every pond, quarantine tank or aquarium. 10% to 15% weekly water changes are considered customary depending on the number and size of the fish and the size of the vessel. This is also the only way besides filtration to reduce the concentration of contaminants in the pond, especially dissolved organics and nitrates. Recently, several types of freshwater foam fractionators have been introduced which do a nice job of reducing DOCs. Whether DIY or commercial, they all seem to work pretty well.

Almost any pond with fish needs adequate filtration as well as aeration for the health of the fish. These two issues must be addressed but the type of filtration and how aeration is accomplished is better considered before building rather than after the fact. Waterer changes may require a dechlorinator as most mains water contains at least some chlorine and/or chloramine. Treat accordingly and dose it at the same time in the same manner every time so that it becomes a habit and is not forgotten. Sodium thiosulfate crystals are a very inexpensive way to dechlorinate. Mixing 1&1/2 lbs of the crystals with one gallon of water will yield enough dechlorinator to treat about 85,000 gallons.

Water changes means actually pumping or siphoning out a percentage of the existing pond water-not just adding to it-and making sure the new water temperature matches that of the pond or tank involved. To ensure success, it is best to connect a timer so that when you forget to turn off the hose it is done for you! Again: a reminder to add dechlorinator if your water has been treated with it.

Part Six/Test Kits:

Hach Chemical Company

Hach Company
P.O. Box 389
Loveland, CO. 80539

LaMotte Company
P.O. Box 329
802 Washington Avenue
Chestertown, MD. 26120

Taylor Technologies, Inc.
31 Loveton Circle
Sparks, MD. 21152-9206

All three of the above named companies are known for their excellent test kits. If you want to use the best and protect your wet investments call one of them and "get it started". They will all use total alkalinity test kits as Kh or carbonate hardness.

Aquarium Pharmaceuticals and Tetra test kits are available at most pet shops and pond suppliers.

Note: If the test kit looks old or dusty, it has probably been on the shelf far too long and is outdated. Check for dating before you buy. Liquid reagents have a shelf life of one year. Powdered reagents have a shelf life of up to four years.

Part Seven/Common Abbreviations:

Kh=carbonate hardness, or for many hobbiests, total alkalinity. It is usually measured in PPM.
PPM=parts per million.
GH=general hardness of your tap or pond water. It is measured in grains or in PPM
PP=potassium permanganate (KMn04). A strong oxidizer. It is used for parasite control and reduction of organics.
FMG=formaldehyde and malachite green. ProformC, Broad Spectrum Disease Treatement (BSDT), and Terminate are common trade names. It is used for parasite control. The product will read as "ammonia" if you test the water.
FMC=formaldehyde, malachite green and methylene blue. Parasite control-especially Ich.
ANN=ammonia, nitrite and nitrate. The primary tests for water problems.
IP=intraperitoneal injection. The injection site in front of the vent behind the ventral fins and just off to the side of an imaginary "centerline", at approximately 15 degrees with the needle pointed toward the head.
IM=Injection site in the muscular region of the body either side of the dorsal. Not for the untrained.
SAP=Saprolegnia. The genus of water molds responsible for significant fungal infections of freshwater fish and eggs.
PCS=Plastic Cover Slip
ST=sodium thiosulfate. A dechlorinator commonly in crystal form but also in liquid. Goes by many trade names but most do about the same thing.
DIY=do it yourself.
GFCI=A moisture-sensitive circuit breaker. A very good thing to have in the electrical box for pond use. In most areas it is code. Another device commonly used is a GFCI receptacle. This is the wall mounted one which you will commonly find in the bathrooms of many homes. It has a reset button on it. These are known for their short lifespan and the inability to hold a circuit as they age.
Scrape and Scope=A procedure which can help identify parasites with a microscope. A microscope is equally as valuable as medications, perfect water conditions, and your most expensive fish. Expect to pay about $400.00 for one which can be used to identify parasites.

Part Eight/Behavioral Symptoms Which Should Send The Alarm:

There are many unusual behaviors which can cause concern. Observe for those which repeatedly occur. Isolating from the rest of the herd, laying on the bottom especially if the fins are clamped to the body, a head down attutude, a head up attitude, dark pigmentation, sandpaper-like skin, breaching(partially jumping above the water surface), repeatedly flashing or rubbing against the pond floor or walls, a slimy-white excess slime coat, not eating, spitting, coughing, shaking of the head and so forth.

Part Nine/Quarantine?

If you haven't and you're reading this it's probably too late. The next time you acquire a new fish it should be quarantined for at least six to eight weeks in water from your pond or from your mains supply. In addition, it is always good to place one of your present collection with the newcomer. A buddy is always good, and it ensures that the existing population will not be adversely affected by the newcomer's bugs. I assure you, they will have bugs. There is No such thing as a Sanitized fish! 

Quarantine tanks are a necessity. Many people sadly relate their experiences of putting a new fish in with the existing population and watching as they all begin to behave in unusual ways and one by one begin to die.

During quarantine, many collectors wisely treat their new arrivals with a standard parasite treatment such as FMG & AquaMeds AquaPrazi for flukes. The customary protocol calls for 100ml FMG or 150ml ProformC per 1000 gallons. Begin by increasing the aeration significantly. Three consecutive treatments of FMG or ProformC over three days. Small water changes such as 20% should be made to enhance the performance of the chemical.

Then, after making a water change, measure and add an appropriate dosage of AquaMeds AquaPrazi and allow it to stay in the tank for 7 days. Repeat this as a second and final treatment.

Part Ten/Scrape and Scope Parasites Common To Koi And Other Ornamental Fish:

Most hobbyiests will never use a microscope. A higher percentage of hobbyiests will use a micrscope if they are members here and are members of a koi club. Still that will amount to a very small fraction of the koi hobbyists. But I will emphasize this point: A proper scrape and scope of skin and gill samples from your koi will probably save their lives.

You'll need a microscope with 10X oculars, and three objective lenses such as 10X 20X and 40X. A box of glass slides and a box of plastic coverslips are needed for taking samples. I learned how to do it without any hands-on instructions so I would imagine you can do it as well.

Use the plastic cover slips for taking samples. To get a gill sample it is important to sedate the fish so read that section again. Once sedated the fish should be placed on a wet terry towel. If possible have an assistant to do things like revive the fish. 

Carefully open the outer gill plate far enough to slide a plastic coverslip in toward the white cartilage at the front of the gills. Then gently but firmly press down with the PCS and pull it back toward you. Hopefully you will see a fairly bloody red, mucousy sample on the edge of the PCS. Take this sample and carefully turn it face down on a glass slide. Press very gently to spread it out. Do not add water. If you place the coverslip in a vertical fashion using the glass slide as East/West the leading edge of the coverslip will be plainly visible when you focus the 'scope and you will be able to move the slide up and down, while also moving the slide from leading edge inward.

It would be wise to get two or three more gill sample as flukes and other little animals have a habit of only populating one area and sometimes are not on both sides. While skin/slime samples can be valuable, I have seen it time and time again that the parasites are in the gills.

A microscope is needed to view these:

Ichthyobodo Necatrix - Costia----------300X-400X:

Costia reproduces quickly when conditions are right. Reproduction is by binary fission. The symptoms are varied. Lethargic, disoriented, dark pigmentation, clamped fins, reddening at the base of the dorsal, thin slime coat or sandpaper like feel are all indicators. More advanced cases will produce a notch above the mouth and the eyes will become sunken. Infections of costia commonly occur around the base of the dorsal fin.

Under the microscope Costia looks somewhat teardrop shaped and moves with the irregularity of bumper cars at the county fair. Cell streams are sometimes mistaken for costia. Cell streams all move in the same direction. They vary in speed but are not to be mistaken for costia.

Costia can be eradicated by applying heat but it takes several days. At 87*F. Costia is immobilized and can no longer reproduce. Unfortunately most pond settings do not allow for heat to be applied to this degree. For those situations either FMG or FMC will work well. Prior to dosing a 25% water change is advised to reduce the organics and improve performance of the chemical. I would advise using 37% formaldehyde mixed with malachite green at a rate of one-gallon formaldehyde and 15 grams of malachite green. The dosage for costia is100ml per 1000 gallons. Weaker products such as ProformC require 150ml per 1000 gallons. Two dosages about 18 hours apart seems to be effective but with higher organics present a third dose may be required.

FMG is made from readily available stock ingredients. But beware! This is not something to take lightly. Neither chemical are particularly friendly to your eyes, nose, mouth or skin. The formula is listed below. Formaldehyde will read as ammonia during the first 24 hours of treatment.

FMG: To one gallon of 37% formaldehyde, add 15 grams of Malachite Green. That's it. Cover it securely and shake it to dissolve the MG powder. Wear protective eyewear. a breathing mask and gloves. Malachite Green migrates easily in even the slightest bit of air movement so be careful.

FMC: An older formula developed in 1978. To one gallon of 37% formaldehyde, add 12 grams of malachite green and 12 grams of methylene blue. This is particularly effective against Ich. Again, be careful with these materials none of them are "exactly" safe.


This is placed under the Ithyobodo Necatrix/Costia heading for a reason:

Many suspected KHV cases are actually Costia infestations. Because Costia reproduces so rapidly and is so devastating to the gills and slime coat it sometimes presents itself as Koi Herpes Virus.

If you suspect that your fish are suffering from KHV due to decimated gills and a thick milky slime coat, here are the steps to take:

1. Treat your pond with 100ml Formaldehyde and malachite green per 1000 gallons of water immediately.
2. Obtain sterile swabs with shipping tubes from you veterinarian. Veterinarians get these free from their suppliers so don't hesitate to ask for them.
3. Swab the gills and body of the affected koi with the sterile swabs. Place the swabs in the tube and refrigerate it.
4. At the earliest convenience send the swabs to the University of Arkansas/ Dr. Andy Goodwin, for analysis. Google the address. It isn't difficult.
5. After 18 hours retreat your pond with FMG.
6. Consider repeating this a third time but if the fish appear to be recovering, just add salt at a rate of .3%
7. Await the result of the tests.

If it was Costia the symptoms and the losses will be minimized. If not and the test results are positive you will have some serious choices to make.

Chilodonella -Chilo--------------------200X:

Chilodonella has a distinctive round shape. It moves like the mother ship in space. Fairly slow under the scope, and cilliates wave from it's outer ring. When using a microscope to find flukes, Chilodonella is easily identified.

Chilo is easily eradicated with either salt at .6% or 100ml FMG per 1000gal. The salt treatment has an overall duration of 14 days, so the only reason to use it is if no FMG is available. There are no ill effects using salt at this level. After the treatment is complete a series of water changes should be completed to slowly reduce the salt level to just that of the raw(incoming)water.

Either treatment will be effective but in the case of FMG it is important that the organics (dirty water-poor water quality) be removed somewhat with a minimum 25% water change to improve the performance of the chemical.

Trichodina -tricky---------------------200X: FMG or FMC treatments work well.

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 tissue 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.

Salt will kill this parasite but it has to be in a strong enough dose. Salt at .6% will kill Trichodina. The salt must stay in the water for at least 14 days to kill any baby trichodina. FMG would be the more desirable treatment as it acts quickly. FMG or FMC can be used if your water is 55 degrees or abouve

Ichthyophthirius multifilils -ick----------200X:

Known as white spot. Easily seen on the body with the naked eye. The problem often experienced with koi is that it is only on the gills and so is not observed except for symptoms of flashing like so many other parasite infestations. Salt at .6% along with an increase in temperatures usually is enough to eradicate them. Either FMG or FMC are effective treatments made even more effective with an increase in temperature. Ich also is known to become quite active during barometric swings. The Florida fish farmers nearly always treat their fish for Ich following a strong thunderstorm.

Take note:

Salt may be used with ProformC, FMG or FMC with absolutely no adverse reaction. If you don't believe that, talk to a fish pathologist.


Hexamita Specific Treatment

Make your own Hexamita specific medicated food using Metronidazole:

Using a medium size bowl, mix 1/2 teaspoon of knox Gelatin in 1/2 cup of warm water. Then add 1/2 teaspoon of Metronidazole powder. Mix thoroughly. Then add one pound koi food pellets into the mixing bowl. Mix this concoction thoroughly. Pour this mixture onto waxpaper and let completely air dry. Overnight drying should be sufficient. Store your new medicated food in air tight bags and refrigerate.

Feed this medicated food ONLY(no other foods) for 10 days. Feed generously, but make sure the food is gone in about five minutes or less.

Note: If you wish you can make a fecal squash for microscopy both before and after the feeding protocol to insure success. Otherwise, regard this as a shotgun type treatment and observe the fecal waste of the fish for brown (normal) segments.

Metronidazole powder is available at FTFFA.

Dactylogyrus - gill flukes---------------100X:

This parasite as well as skin flukes rarely kills koi, but don't be fooled. Infestations of the gills by either gill or skin flukes can cause irrepairable damage. It is a known carrier of aeomonas and pseudmonas bacteria which it injects while feeding on the gills and body of the fish, and if left untreated that WILL kill koi.

It is easily seen at minimum magnification and is distinctive due to it's eye spots and it's stretching and contracting of the body while feeding. Gill flukes are egglayers. Colder water means a longer gestation period. Most of the time I find that treating for a period of two to four weeks is not out of the question and in fact is necessary to "catch" those eggs which must be hatched to accomplish control if not complete eradication.

Treatments are indicated below. Praziquantel is very effective but the water must be in the mid-seventies to improve the medication's abilities. Some say that potassium permanganate will work. I believe it is more correct to say that it may temporarily knock them back but they will recover. Salt has little effect. Kusuri Fluke-M is easily the most effective and yet the most benign of all fluke treatments.

Gyrodactylus - skin flukes--------------100X:

Skin flukes are similar to gill flukes but lack the distinctive eye spots. They may be named skin flukes but they nearly always appear in the gills as well. These are live bearers and so their life cycle is somewhat shorter and they seem to be easier to eradicate. Nevertheless they are dangerous simply because they are carriers just like gill flukes.

Treatments are as above with gill flukes.

A scrape and scope is needed to find flukes. The most likely area to find them is on the gills. Take two samples from each side of the gill tissue. One from the upper edge and one from the lower edge. It is not uncommon to find them only on one side and sometimes on the upper or lower area only. To say that you've only found one or two so the infestation is not severe is simply not correct. When you consider the tiny sample if you find a couple, just imagine how many more there probably are. Scrape and scope: Be complete! A single sample will not give the needed information as to how far the infestation has progressed, and many times a single sample does not take into account the previously described variability in where they happen to congregate.

Argulus - fish lice---------------close visual inspection/Diflubenzuron, several trade names for this. The best I've found is Adept. It is commonly used in the greenhouse trade and is readily available.

Lernaea - anchor worm---------close visual inspection/Diflubenzuron. Adept is one of the trade names.

At best, parasites open the doors for bacterial infection. At worst, they are carriers of it. That is why it is so important to try to identify them and treat for them properly.

Part Eleven/Topical Treatments for koi and goldfish:

While treating for parasites is very important, treating the resultant ulcerated area is equally important. Some will say to use hydrogen peroxide, then iodine, then dental adhesive to cover the wound. I have no argument with using all three, if they are available and you're proficient treating with all of them so the koi is not left on the table too long. Most people are not that proficient. I've treated many many koi and until recently the only topical I've ever used was iodine. It is extremely effective. Swab the wound thoroughly making sure to get underneath the skin and/or scaled edges. Remove any loose scales during this treatment as they will fall off anyway. This is generally a one time treatment.

Further swabbing if any healing is evident will injure the new tissue which is slowly forming around the wound(pale pink to white in color). Further deterioration of the ulcered area after a thorough swabbing indicates the need for a more accurate parasite discovery or a more accurate dose of antibiotic or a change in the antibiotic used.

An alternative to iodine is gentian violet. This seems to work equally well and since it initially colors the area and then fades as it wears off is equally as valuable as iodine as an indicator of healing. Gentian Violet is available as a non-prescription med at most Walgreen/CVS pharmacies.

The third method which I have used and have had extremely good success when nothing else seemed to work is a 50/50 mix of Tricide Neo and Silvadene(a burn cream). This mixture works where most other topicals will not. Silvadene is a prescription product. Work this mixture in slowly and allow it to "stand" for a total of five minutes. Wipe off the paste at that point and revive. Inject an appropriate antibiotic such as Fortaz at this time, along with an single injection of vitamin C. Although the common thought is that injectible vitamin C boosts the immune system, the truth of the matter is that vitamin C is primarily used to reduce the pH of the body thus weakening the bacterial infection primarily to the effects of the antibiotic.

A fourth method is a drop of water on a tiny number of potassium permanganate crystals is only suggested if everything else seems to have failed. This not only kills any bacteria in the area but has a detrimental effect on the flesh which it touches. It kills tissue in the area, so be careful how far you swab with this. I have used it in extremely difficult cases where it becomes a kill or cure situation. I have had very good success using it but I have only used it after I've tried everything else. The area treated takes up to several months to recover where areas treated with iodine or gentian violet are a few weeks.

Potassium Permanganate is an Oxidizer! It is a dangerous chemical if used improperly! Use protective clothing and gloves. Wear goggles/eye protection!

1. Iodine first.
2. Gentian Violet second.
3. Tricide Neo and Silvadene third.
4. Potassium Permanganate fourth.

Swabbing is generally done with Q-tips. Where the surrounding scales are deteriorating I pull them, clean and treat the area to hasten the healing process. A strong tweasers is needed to pull scales.

Part Twelve/Stocking the medicine chest for parasite and disease control:

To start with, a plastic tool box from a big box store will do for keeping all your supplies in one place.

Here's a list which will get you started:

1. Sharp tweasers.
2. Blunt heavy duty tweasers.
3. Small sharp scissors.
4. Scraping device such as exacto knives.
4a. Cotton bath/hand towels used wet in a flat pan or tote lid-holds the fish nicely.
5. Q-tips.
6. Bottle of Iodine.
6a. Clove Oil for sedation.
7. Bottle of Gentian Violet.
8. Small packet of Tricide Neo used as a paste with 8a.
8a. Silvadene-a burn cream which aids healing when mixed with Tricide Neo as a paste.
9. Nitrile, plastic or latex gloves.
9a. Suturing kits for split fins. Braided silk is my favorite.
10. KUSURI fluke-M-by far the best treatment for flukes-also kills snails!
10a. Praziquantel (flukes treatment). Very good flukes treatment. Just takes a couple more treatments.
11. FMG/ProformC/FMC (other microscopic parasite treatment).
12. Dimilin/diflubenzuron (fish lice and anchor worm treatment).
13. Digital Gram scale (eBay-Oldwillknott site).
14. Small cups for measuring.
15. Assorted syringes(no needles)for measuring(10-60CC).
16. Thermometers(aquarium style-at least two).
17. Test kits-Ammonia, Nitrite, Nitrate, Salt, Ph, GH, Kh.
18. Hydrogen peroxide.
19. Oxolinic acid for short baths.
19a. ChloramineT for bacterial gill infections used as a short bath.
20. Flashlight and a new pack of batteries.
21. Assorted syringes for antibiotics and injectible VitaminC.
22. A microscope with slides and plastic coverslips for identifying parasites.
23. An injectible antibiotic such as Fortaz which can be kept in the freezer and reconstituted
at a later date.
24. Water softener salt.
25. An understanding and cooperative veterinarian.
Part Thirteen/Medications:

Be aware that there are companies and individuals who are marketing remedies which purport immediate healing just by dumping it into the pond. The labels will say it will cure just about anything and smell good doing it. Label claims such as this should make you wary; for good reason. These products generally don't work. Yet they are packaged and sold in nearly every garden store across this country. Go figure. If you find a product which states it will do just about everything, don't count on it.

KMno4 - Potassium Permanganate:
Potassium permanganate is capable of doing great things in terms of parasite control, but it is also capable of rapidly killing all your fish if used improperly. This is a poison. The "dip", which is described further on in the Sticky is very effective and is fairly safe because of it's precise nature. PP, when used in a pond setting is only as good as the person using it. Too strong and the fish will suffer and die. Too weak and the parasites will laugh at it. PP is an oxidizer! Wear protective clothing/gloves! Wear eye protection! Wear breathing mask!

For it to be effective in a pond the pond itself must be in fairly good shape, clean and free from organics(waste-plant debris etc.). The pond capacity(gallons) must be known. No guesswork on this.

For microscopic parasites excluding flukes use 2ppm KMNo4(potassium permanganate) in a clean pond. Two consecutive days and do not reverse the chemical. Add aeration. Be prepared to reverse the treatment with dechlorinator if you notice the fish in obvious discomfort. Before you do this treatment for the first time it would be wise to discuss it on this forum. Start a thread. There is some evidence that PP has a negative effect on smaller koi-fry.

The Dip
A dip of 8 grams KMN04 per 40 litres of mid-seventy degree water can be used but for no more than 2.5 minutes. Precise measurement is critical. Aerate. This dip requires several containers as well as an uncontaminated pond or q-tank to place the treated specimens. Pre-dip and post-dip containers are a must. Make sure they can be covered securely. This is a bit over 200ppm! Dips only work if the container(pond)the treated fish are being returned to is parasite free.

A gram scale is required to measure this chemical. Please calibrate it frequently.

For 1000 US gallons here is a brief chart:

PPM---------------Grams needed:


Any dechlorinator or hydrogen peroxide will reverse this chemical. Make sure you have enough to neutralize at least twice the amount used.

ProformC or Formaldehyde and Malachite Green:

This treatment is safe at temperatures of 50*F to 80*F.
FMG is effective on all microscopic parasites except flukes. This is a poison. It is dosed in amounts which will effectively kill the parasites without killing the host. Overdosing may damage or kill your fish. Formaldehyde is generally available from farm supply stores. It is 37% formaldehyde and 11~14% methanol. Malachite green is available from The FTFFA store online. The formula is one gallon of 37% formaldehyde and 15 grams of malachite green.

Commercial mixes such as ProformC are available from pond and koi suppliers. While it is a bit weaker it still works well. It also gives the end user a larger margin for error. It is 22% formaldehyde and about 7.5% methanol mixed with a proprietary amount of malachite green.

The following treatment is suggested by many: Three treatments, daily with 25% water changes before each treatment. 100ml per 1000 gallons FMG or 150ml per 1000 gallons ProformC is considered the best as well as the safest dosage. On the third dose combine FMG or ProformC and Praziquantel and allow to stand for seven days Another treatment should be considered after seven days AFTER a 25% water change. See the paragraph below for Fluke Specific treatment. Salt in the water will not significantly affect the treatment or the fish. This treatment is for all parasites and it is temperature/life cycle dependent. Flukes can take 30 days to eradicate if the water is in the low sixties. This takes several retreatments. Warmer waters reduces the time frame.

Malachite Green Stock Solution
15 grams makes one gallon. Thereafter use one drop per gallon. This is a great Ich treatment when combined with increased temperature for a few days. It has been used for many years by accomplished aquarists on their collections as well as fish farmers in Florida. For those with planted aquaria or ponds the plants seem to suffer no harm. Malachite Green should only be used/mixed when wearing eye protection, a good breathing mask and protective clothing! Malachite Green dust easily migrates with air movement. Be careful!

Praziquantel: Gill and Skin Flukes:

A trematodicide. Praziquantel induces a rapid contraction of schistosomes(a worm or fluke)by a specific effect on the permeability of the cell membrane. The drug further causes vacuolization(causes more and larger spaces or cavities within each individual cell)and disintegration of the cells as well as the Schistosome tegument(the fluke body covering). Bursting or breakdown of the cell walls might be a much simpler way of describing it and may be equally correct.

Praziquantel must be ingested by the fluke to work. The dosage is one gram per 100 gallons of water. Currently the directions suggest using level tablespoons to measure the product. That is a mistake. In my experience a level tablespoon may hold anywhere from 2.5 to 4.5 grams of product. Not only is this wasteful and inaccurate; it is also very expensive. Please use a gram scale. Calibrate it often.

Since it does not mix readily with water a standard FMG dosage may be used, or it can be dosed with the FMG as part of the treatment described above. Once it is fully dissolved it does not seem to filter out or precipitate. It simply degrades over time. When using Praziquantel, the water temperature should be in the mid-seventiesF. The first and all succeeding treatments should last seven days each whether treating for gill flukes(Dactylogyrus) or skin flukes(Gyrodactylus). 25% water changes should be made between treatments. Redosing will immediately bring it to the strength needed to kill flukes. I strongly recommend a third or even fourth application of this product due to the life cycle of the flukes as well as the thickness of the slime coat on Koi. In colder waters (60*F to 70*F) a fourth application is usually necessary when treating for gill flukes. Because of the cost of Praziquantel and the reduced treatment time it is well worth the effort to bring the temperature up to optimum. Another way to reduce cost is to simply lower the water in the container or pond to be treated.

Praziquantel "It doesn't seem to be working":

Koi are bottom feeders. They excrete an abundance of slime to the gill area which protects the gills, as well as the parasitic gill and skin flukes-yes skin flukes are commonly found in the gills, from the debris passing through them. So repetition of the treatment is necessary to allow time for gill flukes, in particular, to ingest the "poison".

Kusuri Fluke-M

I've been working with this product for about four years. I can tell you that this is the best, safest water column medication for flukes that I have ever used. The directions are simple, and there is little problem with a mild over-dose.

After using the treatment on several collections, it appears that two treatments spaced seven days apart in waters about 70degreesF seems to be very very effective. My attempts at finding flukes on koi treated with Kusuri fluke-M have been futile----a very good thing!


Know that this product has been accused of burning fins and suppressing the immune system. This accusation has been substantiated by several members of Koiphen. In the UK, there are more reports surfacing regarding the long range effect on the immune system as they have been using it for several years longer than here in the US. Therefore I would strongly urge that it be avoided. There are several methods for reducing flukes which are much safer. It is not recommended here.

Organphosphates-Fluke Tabs:

Fluke Tabs work well in waters where the Kh is less than 170ppm. Above that the poison is bound by the water and becomes ineffective. Attempts at double and triple dosing in high Kh waters results in killing the flukes AND the fish.


An older type dewormer which seems to work at times, the dosage is 1 gram per 100 gallons and is used the same way as Praziquantel.

Chloramine T Dip:

For bacterial gill disease. This is very effective as a dip. Dosing is 1 gram per 10 gallons, five days consecutively for one hour. Do not mix this with any other treatments. Use old (conditioned) tank or pond water with aeration. I have not seen any printed directions for this, nor am I aware of any others who have used it this way. I have used it on several occasions including a shipment of 180 small Japanese imports. It has proven to be very effective yet appears to be completely safe. Using it in the pond or quarantine tank will kill the beneficial bacteria in the filtration system.

Diflubenzuron 25% wettable powder:

Diflubenzuron is a controlled and, usually registered, pesticide which requires a license to use, sell or distribute.

Diflubenzuron is commonly used as an insecticide for greenhouse use. This powder works well in eradicating anchor worm(Lernea)and fish lice(Argulus). One gram will treat 3000 gallons. It is quite forgiving and an overdose usually will not cause irrepairable harm. The parasites should be removed by soaking them in iodine and pulling them carefully with a tweezers. Sedating(described below)the fish will prevent uncontrolled thrashing and further damage to the fish during this process. No ill effect is noted from sedation.

There are liquid forms (Dimilin) on the market. Follow the label directions.

Part Fourteen/Salt:

Salt has been used on such a large scale and usually for no reason that most parasites are resistant to it. However it still has it's place. Using it at a .6% - .7% level is excellent when bringing in new fish to a quarantine tank. If your dealer suggests using salt then follow his or her directions. Salt is effective on all microscopic parasites at this level. At least it knocks them back a bit giving you some time to determine what further treatments, if any, which you might use. See statements below for an overview on salt:

Salt is known to protect fish from nitrites. The percentage of salt in this case is .15%. When adding fish to a pond or q-tank pay attention to ammonia and nitrites!

Salt is required, at least so the story goes, when using Elbagin(a Japanese water column antbacterial agent very similar to Nitrofurazone). The percentage of salt in this case is .6%.

Salt will aid in osmotic regulation of an immuno-depressed fish as well as koi with damaged gill tissue. It is used at a rate of .15% to .3%. New imports, as well as fish with bacterial infections are sometimes treated to aid their recovery. The percentage of salt used this way varies. I prefer .6% with new shipments of domestic butterflies and all goldfish. Be aware that salt may adversely affect some medications but has no adverse reaction with ProformC, FMG or FMC.

Several parasites can still be controlled successfully with salt. The percentage of salt in this case is .6%. The treatment is not too temperature dependent and the duration of the treatment should be 14 days. Some strains of microscopic parasites are no longer deterred by salt.

For informational purposes here is how to calculate salt:

.1% salt in 100 US gallons is .8333 pounds.
.1% salt in 1000 US gallons is 8.333 pounds.

.3% salt in 100 US gallons is 2.5 pounds.
.3% salt in 1000 US gallons is 25 pounds.

.6% salt in 100 US gallons is 5.0 pounds.
.6% salt in 1000 US gallons is 50 pounds.

.15% salt in one US ton(264 gallons) is 3.313 pounds.(preferred for reduced nitrite uptake)

Aquariums or qt - Apply one teaspoon of non iodized table salt per gallon of water every 12 hours for three treatments:
3 tsp per gallon for .3%.
6 tsp per gallon for .6%

Salt and Nitrites:

Dosage is .15%. Salt will slow if not stop the uptake of nitrites.

Part Fifteen/Fungal Infections

Sap or Saprolegnia is the main genus of water molds which can bring about significant fungal infections in fish and eggs. It's safe to say that all ponds have water molds in them. Unless the fish are compromised the slime coat will, in most cases, protect the fish from an invasion. Sap invades epidermal tissues In common with all molds, it does so by secreting digestive enzymes into the surrounding areas. Since enzymes in general break things down it's easy to understand that this secretion enables the fungi to more easily absorb nutrients from the affected area. SAP slowly is digesting the fish! at this point it is called saprolegniasis. It sometimes has a green haze which is the fungal infection combined with algae. It is best to scrape and remove this growth before topical treatments. A surgical scalpel works well for this purpose.

SAP can spread over the entire body, but is usually spotted as pale white or grey patches. Sometimes it will be green if algae has been caught in it. It is usually considered to be a secondary infection seen after damage to the fish skin or gills. However it can be primary as it is temperature dependant, occuring in cooler waters as a consquence of immune system shutdown.

SAP Treatment:

At one time it was generally agreed that Malachite Green was by far the most effective treatment. However, a treatment for topical bacterial ulcer disease has shown a very serious advantage. Tricide Neo, produced for dips and sprays has now been used for topical swabbing when simply mixed with the slime of the fish. It is important to continue to work this into and under the scales and flesh of the fish for about 5 minutes. Then simply wipe off and revive the fish. The results have been extremely good. It remains to be seen if this will become a staple in the medicine cabinet for SAP but it definitely has proven, in the short term, that it works.

The following is older information but Gentian Violet still is an important tool in the medicine cabinet.

Gentian Violet may also be used as it is antifungal. GV is available over the counter at most pharmacies. It is very inexpensive and easily applied without the mess of mixing or the dangers of Malachite Green.

Columnaris: Mouth Fungus; Fin Rot, Cottonmouth Disease:
This is not a fungus or a mold. This is a bacterial infection-gram negative. The problem is that it can somewhat resemble SAP. Symptoms include grayish white spot on the head, gills or body sometimes surrounded by a reddish tinge. It can be topically treated with Iodine and then given antibiotic injections per the charts listed in that section. I would, however, strongly suggest the use of Tricide Neo as the topical of choice when used as a paste mixed with either slime coat, or even better, Silvadene.

Part Sixteen/Dropsy:

The term "Dropsy" describes the symptoms of more than one kind of disease, but all of which share the same symptoms of a bloated body with protruding scales. The accumulations of fluid within the body causes bloating, that becomes more severe in a short time. The scales stand away from the body and the term "pine-coning" is used to describe it . As the internal bacterial disease progresses the eyes will be affected, causing them to protrude or bulge as well. Recovery under these conditions is very rare, and death is inevitable.

Part Seventeen/Sedating a fish for treatment:

Clove oil at a rate of 12 to 16 drops per gallon will calm a fish in a matter of minutes. Larger koi generally need more but each koi is different in the reaction to a sedative. Add the clove oil to a small container of water which can be shaken thoroughly. Then add it to the sedating bowl. DO NOT LEAVE THE FISH UNATTENDED DURING THIS TIME. Use only enough water to cover the fish. Aerate. When the fish lays over on your hand without flopping and while still having gill movement it is ready for treatment. Practice this a couple of times keeping a supply of fresh but aged water close by. If for any reason you feel the fish has become sedated too deeply, simply move it to fresh aerated water and assist the fish in using the gills and hold near aeration. Assist the gills by moving the fish back and forth forcing water to pass over the gills. Use your middle finger in the mouth with one hand and hold the tailstop gently with the other.

MS-222: Tricaine Methanesulfonate. This can be fairly tricky at first so practice is important. Using a gram scale measure out two grams of MS-222 and two grams of baking soda. MS-222 MUST be buffered. Without the buffer, the Ph of the water to be used will drop as far as 3.3! That is ACID. In a matter of a few minutes the gills will be compromised and after several more minutes the fish skin and gills may be permanently damaged.

Add the MS-222 and baking soda to five gallons of aged pond or q-tank water. Mix thoroughly and you are ready. DO NOT LEAVE THE FISH UNATTENDED DURING THIS TIME. As the fish becomes sedated it will lay over and become quiet and easy to handle. If at any time you think it is too far sedated revive it at once by holding it in a tub of fresh untreated water and move it back and forth assisting it in using the gills. Once sedated, a fish can be tabled for 5-10 minutes without worry. The first time is usually far more stressful on the owner than the fish.

I hope this information has been valuable & you can put it to good use. I'm often asked if I have a favorite book on Koi Health, and if you've made it this far in the blog, then I think you are deserving of that answer. While we don't currently sell it, this is one I enjoy the most. 
Koi Health & Disease 2: Beginner to Advanced Life Saving Technology, by Erik L. Johnson, D.V.M.  
There is also some good resources available on, including this Koi Health Advisory (KHA) article (PDF)
Koi health




Are you saying 256.5ppm to 513ppm hardness is KH and you well never have to add anything (I assume Baking Soda). To your pond. Try the number 125kh. Not the high numbers you have posted.



You say ulcer disease and dropsy occur with high levels of nitrate. Nope. Here are the symptoms. Loss of appetite
Rapid gill movement, high respiration rates
Listlessness, acting dazed
Loss of equilibrium, disorientation
Laying on the tank bottom
Curling head to tail (advanced stages



You say 200 level kh for bead filters.This is absolutely false. Mine worked great at 100 when I first cycled and some others I know experienced the same thing. Were did you get this misleading information? I talked to a bead filter company and asked them this question. He just laughed and said bio is bio and cycling requires about 90 for any system even bead filters. He was a water expert with a degree.



You say 1.5 are high levels for nitrite. However every article I have read says. .15 should be the limit for koi?



You say 1.5 are high levels for nitrite. However every article I have read says. .15 should be the limit for koi?

Larry Schultz

Larry Schultz

I am impressed with the thoroughness of this information!
Thank you

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