Potassium Permanganate & Koi 13 December 2019

Disclaimer : This article is only available as an opinion. It is absolutely you’re (the user) choice to read, adopt or use any opinion contained within this article. Utopia Koi and the company directors accept no responsibility for loss, damage, death or other that occurs to either you, another person, you’re fish or your property because you chose to read, use or adopt any opinions contained within this article. Potassium Permanganate is a very dangerous chemical that can cause illness, blindness or even death. If you are in any doubt about Potassium Permanganate (KMnO4) or when using Potassium Permanganate follow the instructions on the product packaging given by the manufacturer.

If you do not accept this disclaimer do not read, adopt or use any opinions contained in this article.

Utopia Koi always recommends consulting a professional veterinary partitioner prior to the treatment of any live animal.

Kusuri Potassium Permanganate

So lets start off with a few simple Potassium Permanganate facts 
  • Potassium Permanganate is one of the most potent pond treatments available for use within a Koi pond
  • Potassium Permanganate has been readily available for over 200 years and is one of the most widely used treatments in commercial fish farms
  • Potassium Permanganate requires a high level of respect when being used and can be very dangerous if care is not taken
  • Potassium Permanganate is a sledgehammer that will kill external pathogens with ease when used in the correct manor the correct dosage rate
  • Potassium Permanganate has an unlimited shelf life and can not become out of date
  • Always make sure you have enough Hydrogen peroxide available incase of difficulties during KMnO4 pond treatments
  • Always use eye protection when using potassium Permanganate
What is Potassium Permanganate?

Potassium permanganate KMnO4 is a caustic alkaline that destroys organic materials through direct oxidation.

In its dry state it looks like deep purple crystals.

It is available in different purities and we would strongly recommend that you purchase Potassium Permanganate in crystal form from a reputable supplier who should guarantee a good level of purity.

What Can You Use Potassium Permanganate for?

KMnO4 is a useful treatment against most types of parasites in a pond.

KMnO4 is a superb treatment to lower bad bacteria in a Koi pond as a disinfectant

KMnO4 is a superb water treatment to reduce dissolved organic compounds in ponds. Keeping the level of dissolved organic compounds to a minimum in a Koi pond will greatly help the overall water quality whilst making the appearance of the water much clearer.

Is Potassium Permanganate dangerous?

KMnO4 is a very dangerous chemical and great care should always be taken when using it. Eye protection should be worn at all times.

Use Protective gloves when handling KMnO4 because it will kill skin staining it dark brown for several days. It will burn skin in the same manner as concentrated acid but It is not a carcinogenic and it is not a toxic substances.

KMnO4 is an irritant. The use of a dust mask gives good protection to the respiratory system and is recommended whilst KMnO4 is being prepared from its crystal form.

Does Potassium Permanganate harm my biological filtration?

YES When treating a Koi pond with KMnO4 the biological stage of your filtration system should be bypassed or isolated.

After a Koi Pond has been treated with KMnO4 we recommend topping up your good bacteria in your biological filer with a high quality live bacteria such as an Evolution Aqua Pond Bomb.


KMn04 should only be used in accurate measurements. You need to know the volume of your pond and you also need a set of accurate gram scales. If you treat KMnO4 with respect and use it correctly is not harmful to your fish. miss use it or use it with out the respect it deserves and it is quite possible to kill everything in your pond.

When using Potassium Permanganate it is strongly recommended to add additional aeration to your pond

  • Never use where the water is above 25 degrees.
  • Never use when there is low of insufficient aeration.
  • Never use in a pond with poor water turnover.
  • Never use if the pond water column is not accurately known.
  • Never use an unmeasured amount of Potassium Permanganate.
  • Never use when the pond can not be attended for the full duration of the treatment.

Part Per Million

  • Parts Per Million which is an equivalent to milligrams per litre or grams per cubic meter.
  • 1 gram per 1 cubic meter of water is 1PPM
  • 220 UK imperial gallons represents 1 cubic meter
  • 220 UK imperial gallons represents 1000 Litres


1 PPM is considered a safe dose, provided that the recommendations are followed. Its very difficult to damage anything except a few parasites or reducing the bacteria level in the pond. This is the minimum dose of KMnO4 and although effective as a broad spectrum bactericide it will fail to kill tougher pathogens.


1.5 PPM is the general recommendation for KMn04 treatments within a koi pond and is the maximum safe dose if sturgeon are kept in the pond.

2 PPM to 3 PPM

2 PPM to 3 PPM is an effective dosage rate against a large number or parasites and bacteria although at this level caries a mortality risk. This dosage is safe in the hand of the more experienced pond owner if care is taken.

4 PPM 

4 PPM is a sledge hammer. In a short space of time it is possible to get very impressive bacterial and parasitic reductions.

A high level of care is an absolute must at this dosage rate. This dosage rate must not be used by novice koi keepers or those that are unused too treating koi ponds with KMnO4. Guidance is recommended from a qualified vet prior to considering the use of KMn04 at this dosage rate.


Potassium Permanganate is a very cost effective treatment against fungal infections, Parasitic infestations and bacterial issues.

Potassium Permanganate is a very useful treatment when moving fish from one pond to another ponds a precautionary treatment.

Potassium Permanganate when used as a short-term bath or dip MUST be measured precisely or fish mortality (Death) is a very high probability.

A dosage rate for a short term bath used by experienced Koi keepers is often 100PPM per 10 litres of water. This equates to 1 gram per 10 litres of water.

The maximum amount of time a Koi should be treated in the bath should be 3 minutes so it is imperative that the person carrying out the treatment is well organised and that the event is timed accurately to avoid damage or fatality to the Koi.


Carefully measure the desired amount of KMnO4 with a set of gram scales.

Carefully empty the measured KMn04 into a plastic bucket or similar that is clean and ready for use.

Carefully mix the KMnO4 crystals with warm water and stir with a wooden or plastic spoon.

Please note that Potassium Permanganate can have a strong reaction to metal so it is strongly advised to use a wooden or plastic mixer

Once mixed disperse the KMnO4 across the surface of the pond. Take several minutes to add the Potassium Permanganate to the pond so that the fish are not shocked. you don’t want your Koi swimming through a cloud of concentrated KMnO4.

Please note that the Potassium Permanganate is active in the pond whilst the water is pink / purple in colour. When the water changes to a brown colour the Potassium Permanganate has been depleted.


This really depends on the type of issue you are trying to resolve and the severity of the issue along with the overall condition of the Koi.

If you have weak fish then a milder shorter first treatment will be required to reduce the problem and hopefully allow the fish to recover a little and then stronger, longer treatment protocols can be adopted. Please note if the fish are weak and they are subjected to a very strong KMnO4 treatment for and extended period of time there is a high probability that there will be high levels of mortality.

As a general guide KMnO4 is used for between 4 and 12 hours.

If your desire is to thoroughly sterilise the pond removing as many bacterial and parasitic infestations as possible an initial dose of 4 ppm can be adopted

4ppm is a sledge hammer and extreme caution needs to be used with this dose rate but it is a supremely effective treatment at this dosage rate.

The pond and Koi need to be monitored for the full duration of the treatment which in general is 6 hours at this dosage rate. never leave unattended.

If the water changes from pinky purple to brown during the treatment duration this simply means that the KMnO4 has been depleted.

If required re-dosing during the desired treatment duration can be carried out but a weaker dosage rate would generally be adopted. The KMnO4 top up can be carried out at a dosage rate of 2 ppm to maintain the active state of the KMnO4 for the full chosen duration of the treatment.

If the Koi exhibit signs of stress during the treatment duration it is advisable to reverse the active state of the KMnO4 with the use of Hydrogen Peroxide


Yes of course different treatment regimes can be used.

You can exchange a stronger / short dose for a weaker / longer dose, and kill just as many parasites which will cause less stress to the fish.

If you consider yourself a less experienced Koi keeper or have less experience using KMnO4 it may be worth adopting a weaker dosage rate and allow the treatment to carry on longer.


Dosage rates are very flexible. The strength of the first dose is flexible as is the strength of the re- dose. Some people choose to dose weaker dosage rates for longer periods of time and dose daily. Some dose stronger dosage rates for short amounts of time leaving a day or two between treatments.

This all depends on the strength of the Koi in the pond and the issue you are trying to resolve.

Some parasites or bacteria die quickly using a short strong dose, while others are better able to withstand strong short treatments and need a longer period of time in the active KMnO4. Other parasites die quickly with a strong first dose, but leave eggs or larvae which hatch after several days recreating the initial problem.

In essence each issue requiring treatment requires a bespoke approach determined by the specific issue you are trying to resolve.

Successful treatment begins with successful and precise identification of the issue requiring treatment.


Confused ? Yes we understand that. Is it pink ? Is it Purple or is that a brown orange colour?

Take a white plastic disposable party beaker and fill the beaker with pond water and observe the colour. If you see pink, purple, red, then the KMnO4 is still active

If you are not sure caution is advisable and do not re dose.

  • Maximum water temperature – 25 degrees
  • Minimum water temperature – Under 12 degrees it is advisable to use a lower dosage rate for a longer time period
  • Turn off ultra violet clarifiers

The following procedure is capable of resolving many issues and could be adopted as a baseline treatment regime. Remove any sturgeon from the pond prior to KMnO4 treatment.

Day 1

2 ppm initial dosage rate, re dosing if the KMnO4 becomes depleted within 6 hours.

Do not treat the pond with Hydrogen peroxide. Simply allow the KMnO4 to become inactive after the 6 hour mark.

Day 2

1.5 ppm initial dosage rate, re dosing the KMnO4 if it becomes inactive within 6 hours.

After 6 Hours remove the KMnO4 with hydrogen peroxide.

Day 3

No Treatment

Day 4

No Treatment

Day 5

2 ppm initial dosage rate, re dose if the KMnO4 becomes depleted within 6 hours.

After 6 Hours remove the KMnO4 with hydrogen peroxide.

Day 6

No Treatment

Day 7

No Treatment

Day 8

1.5 ppm initial dosage rate, re dosing the KMnO4 if it becomes inactive within 6 hours.

After 6 Hours remove the KMnO4 with hydrogen peroxide.


Don’t panic but speed is of the essence.

Before you started treatment with KmNo4 it was advised to have large quantities of Hydrogen Peroxide available.

Hydrogen peroxide is generally sold as a Koi pond treatment at 6% strength. Use 100ml per cubic meter of pond water (220 UK gallons).

Alternatively Sodium thiosulfate Na2S2O3 can be used with great effect. As a general rule of thumb use 10 grams per cubic meter of pond water (220 UK gallons) will effectively remove KMnO4 very quickly.

If a large overdose has occurred and the overdose has been rectified with either hydrogen peroxide or sodium thiosulfate there will be a large amount of manganese salts in the pond water. The manganese salts may settle in the gills of the Koi which have more than likely just been burned leading to further difficulty for the koi to extract oxygen from the pond water. In a case of severe KMnO4 overdosing it is recommended that the Koi are removed and placed in a temporary holding vat or quarantine pond.

General do’s & dont’s


Can Potassium Permanganate and salt be used together ?

There is no reason why NaCl and KMnO4 cannot be used together. If you keep the salt does below 0.5% and the KMnO4 below 4 ppm then you should have no problem.

Trouble dissolving Potassium Permanganate ?

Ensure you are using warm water and a clean mixing vessel. If it takes more than 3 minutes to dissolve the KMnO4 then discard it. The chances are the KMnO4 is low grade and impure.

Can metal be used with Potassium Permanganate ?

No. KMnO4 is a very strong alkaline oxidant. Use plastic or wood

How do I get brown stains off my hands ?

Hydrogen Peroxide is very effective.Simply rise a nailbrush and give the brown stained areas a good scrub. If you choose to do nothing then the chances are it will wear off in a few days.


First and foremost don’t panic. Stay calm, assess the situation and then address the problem.

Brown foam on the pond surface 

This will disappear in a few hours and won’t hurt the fish. It is manganese salts, a residual product of depleted KMnO4.

The Koi look like they have brown spots ?

The brown spots or areas where parasites have been or areas of the fish that have been damaged. The KMnO4 has oxidised the area which stains the area brown in the process.

The brown spots will soon disappear as the Koi heals

Flashing and Jumping Koi

Koi do jump and dart around the pond from time to time. This is normal. They are living creatures that have a mad moment like all of us.

The pond has just be treated with a caustic alkaline which will have caused some irritation to the koi stripping all of the mucus layer away as well as killing lots of the parasitic / bacterial infestation.

It is important to observe the Koi and ensure that they do not jump out of the pond and damage themselves but a level of erratic behaviour is normal and to be expected.

My Koi are gasping for air at the surface ?

Try feeding the Koi a very small amount of food and see if they are simply looking for food. After all your at the pond side and they will assimilate your presence with food. Your just an “auto feeder”. If they eat great. If they ignore it, don’t panic but observe the gill movement of the Koi.

If the gill movement is rapid and constant, and if they open their mouth fully with each gill movement, then you have an oxygen problem. Add additional aeration to the pond water or if this is not available remove the KMnO4 with Hydrogen Peroxide

My Koi are facing down on the bottom of the pond ?

Look at the fish and observe if the Koi are facing the current in a line.

Look at the Koi and observe the gill movements. Are the gill movements slowly and even? Chances are the are simply dormant. The equivalent of fish sleep.

If the gill movement is fast and erratic or if the fish do not look good remove the KMnO4 with Hydrogen Peroxide.

Mucus is coming out of the Koi’s gills ?

The Koi may have parasites in its gills. Keep a careful eye on the fish. If it is obvious that the Koi is trying to get rid of the parasites in its gills then leave the Koi alone and let the KMnO4 do its job.

If the fish is in a state of distress stop the treatment immediately with Hydrogen Peroxide. 

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