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Japanese Koi Carp at sensible prices

Dormer Cottage, Spurgrove Lane, Little Frieth,

Nr. Henley on Thames, Bucks, RG9 6NU

Phone/Fax: 01494 882600

Order Hotline: 07814 011357

last updated 16th May 2021

Medications and Their Uses

At Koi Water Garden, we offer not only all the medications and health products you should ever need for your Koi, but also advice on how to use each medication - why, when, which one and how much.


Virkon Aquatic


  • Virkon is the most proven livestock disinfectant in the world.
  • Fast acting- 1% solution independently proven to kill bacteria and fungi in less than 5 minutes and parvovirus in less than 10 minutes.
  • Independently proven effective on porous surfaces such as wood, against organic challenge, in hard water and at low temperature.
  • High levels of surfactancy with acidic and oxidising power provide superior destruction of biofilms.
  • UK Defra approved at exceptionally high dilutions:- Friendly to man, animals and the environment.
  • Non-tainting, no environmental residue problems, of exceptionally low toxicity.
  • A powder for easy storage and transportation and accurate dilution - readily soluble in tepid water.




  • Complete control - aerial, surface and water system disinfectant.
  • Can be applied to surfaces and equipment to clean and disinfect in a one step operation - passes AOAC detergent sanitizer test at 1:200 dilution.
  • Suitable for use in all types of poultry and animal housing, fish farms, greenhouses and veterinary surgeries.


Chemical and physical properties


  • COMPOSITION: A balanced, stabilised blend of peroxygen compounds, surfactant, organic acids, and an inorganic buffer system.
  • APPEARANCE: Pink/grey powder (yellow/orange in US). ODOUR: Faint lemon odour.
  • ACTIVITY: Strong oxidising system.
  • STABILITY: Powder: 2.3% average loss of initial activity after 36 months at 20°C.
  • 1% solution: only 10% loss of initial activity after 7 days in 350ppm hard water.
  • SOLUBILITY: Readily soluble in tepid water giving a clear pink solution (yellow in US).
  • CORROSIVITY: No corrosive effects on mild or stainless steel when used as directed.
  • HYDROGEN ION CONCENTRATION: 1% solution - pH2.6.

Environmental Impact


  • Ecotoxity: "Non toxic" according to EU standards for soil toxicity; lower aquatic toxicity than peracetic acid and will not present a threat to sewage treatment facilities when used as directed. Water Research Council UK.
  • Environmental effect: "In the dilution normally encountered all of the Virkon ingredients are either decomposed and/or biodegraded and are comparatively harmless. The triple salt of potassium monopersulphate will decompose into harmless by-products. In the aqueous environment the product will eventually degrade and should pose no problem to sewage treatment processes" Anglian Water, August 1994
  • Biochemical Oxygen Demand: In a 5 day Biochemical Oxygen Demand test carried out by Anglian Water a 1% solution of Virkon (subsequently diluted to a level typically found in effluent streams) did not inhibit the BOD test. From this it can be concluded that Virkon was degradable under the conditions of test and as such would not affect the functioning of sewage treatment plants.
  • Biodegradability: Virkon consists mainly of inorganic salts which decompose into harmless by-products. The surfactant is a salt of a straight chain alkyl benzene sulphonate complying with EEC directive 82/243, giving more than 90% biodegradibility under OECD test conditions.




Exposure: No occupational exposure limits are specified for Virkon components according to the requirements laid down in Health and Safety Executive Guidance Note EH 40/95 under the Control of Substances Hazardous to Health, (COSHH) Regulations, 1994.

Irritancy: At 1% in use dilution Virkon is classified as:- Non-irritant to skin, Non-irritant to eyes, when tested according to EU Directive 67/548/EEC.


Dose. See table below For pond treatment. May be used on a weekly basis whilst bacterial or Viral problems are suspected at 1 to 2 grams per 220 gallons. In tablet form - each tablet weighs 5 grams.



Water Hardness: Terms and Conversion mg/l CaCO3 German Degrees of Hardness Described as Dose per 220 gallons
0-50 0-3 soft 2gm
50-100 3-6 fairly soft 3gm
100-200 6-12 slightly hard 5gm
200-300 12-18 moderately hard 8gm
300-540 18-30 hard 10gm
Above 540 30 Plus very hard 12gm
1 German degree of hardness = approx 18 mg/l CaCO3   



Potassium Permanganate


An old treatment but still one of the most popular bactericides available, cheap and effective, can be used at any temperature (see below) and reduces bacteria count and can clean up external wounds on our koi very effectively. Has the added benefit that it kills many common parasites as well. However Potassium should always be used with great caution as it is a powerful oxidising agent and as such will 'oxidise' any organic material in the pond, be that bacteria, parasites, Algae and plant life. In addition it leaves a nasty residue of Managanese dioxide behind, which can stick to and damage the gills of treated fish. It should NEVER be repeated more than twice in any week, as despite what you might read - it is probably one of the most toxic pond treatments which will, without doubt, damage gills of Koi with repeated usage and in addition will certainly damage the biomasss in your filter.


Correct dosing is always problematic, as the required dosage must take account of just how much organic material is present in the pond. So for example, and old mature pond, heavily planted, and with a layer of silt over the bottom of the pond and heavily stocked will require a much higher dose of Potassium than a new, pristine pond with few Koi. Additionally, it is more toxic at higher pH levels, but far less toxic in hard water! So actually calculating the correct dosing of Potassium is almost impossible.


Which is why this treatment is easily underdosed - resulting in its ineffectiveness, or easily overdosed - resulting in damage to or even the death of the treated Koi! The ONLY effective way of calculating a correct dose of Potassium is to use a Redox or ORP meter, which measures the oxidising effect of the treatment in the pond concerned. We would be looking to achieve a Redox level of around 450mv for a short time, at which level the treatment will be effective against our chosen pathogens, but will not detrimentally affect our Koi.


Potassium tends to be effective in the water for only 4 - 6 hours, but despite this the water will go brown and scummy for a day or so after treatment. This seems to have led to a very 'fashionable' trend now to dose the Pond with Hydrogen Peroxide in order to a/ clear the water of the Potassium residue and b/ reoxygenate the water. We DO NOT subscribe to this approach - Hydrogen Peroxide is also a powerful oxidising agent, and whilst it will add back oxygen to the water and clear it quickly, it is also just as potentially toxic to the fish as Potassium and its use is completely unnecessary and potentially adding further risk to the treated Koi. In addition ponds should always be adequately oxygenated for and chemical treatment and we should NEVER use another chemical for this purpose.



Effective against Gill and Body Fluke, Costia, Chilodonella and Trichodina. Aggressive pond disinfectant.


Dose 1.5gm to 2.5gm per ton (220 gallons or 1000 litres). Between temperatures of 5 Deg. C and 18 Deg. A 'standard' dose in hard water is 2gm per 220 gallons or 1000 litres with good aeration, especially for parasite treatment. We would recommend that Potassium is not used at this level when the pond water is over 18 Deg. C. Mix with warm water and leave to stand for 30 minutes before use. Switch off UV. May be repeated after 5 days, depending on temperature. Can be used safely with salt up to ½ oz per gallon.


Chloramine T


Very similar to Potassium, another powerful oxidising agent, slightly more expensive, but like potassium kills bacteria and many parasites.


Must be used above 12.5 Deg. C. Mix with warm water and use immediately.


Switch off UV. Best used in the evenings (breaks down very quickly in strong sunlight)Effective against Gill and Body Fluke, Costia, Chilodonella. Excellent pond disinfectant. Dose dependent on water hardness. See table below Use three treatments, one every other day.


May safely be used with salt at 1/2 oz per gallon.



Water Hardness: Terms and Conversion mg/l CaCO3 German Degrees of Hardness Described as Dose per 220 gallons
0-50 0-3 soft 2gm
50-100 3-6 fairly soft 2.5gm
100-200 6-12 slightly hard 3gm
200-300 12-18 moderately hard 3.5gm
300-540 18-30 hard 4gm
Above 540 30 Plus very hard 5gm
1 degree of hardness = approx 18 mg/l CaCO3   



Malachite Green


Powerful fungicide and mild bactericide that can be used with salt at 1/2 oz per gallon to kill Whitespot very effectively. Use against all fungal diseases as a pond treatment. Used with Formalin as a parasite treatment which can be effective against a range of parasites. Do not use with more salt at more than 1/2oz per gallon (0.33%) if using with Formalin. Use at temperatures over 12.5 deg C.


Dose as recommended by manufacturer.  




Powerful bactericide and parasite killer that can be very toxic indeed - indiscriminate killer of much organic life forms in a pond - only ever use as a parasite treatment as instructed in combination with Malachite Green. Never use this chemical on its own.  Do not use with salt at more than 1/2 oz per gallon (0.33%. Use at temperatures over 12.5 deg C.


Dose as recommended by manufacturer. Warning - Never use Formalin on it's own.



The great tonic, great supportive treatment when treating koi for a wide variety of ailments, can be used as a dip and can be used to kill parasites and bacteria at high strength. Helps lessen the burden on the Koi’s osmoregulatory system (helps keep the koi’s fluid bodily level in balance).


Cannot be used with all chemicals, notably potassium and chloramine T at high strength. Max recommended dosage with these chemicals is ½ ounce per gallon (0.33%)


Dose – For use as a general supportive treatment and ‘tonic’ – ½ ounce per gallon (0.33%). As a supportive when treating bacterial infection with other treatments, such as Acriflavine – ¾ ounce per gallon (0.50%). As a dip – 4 ounces per gallon (2.64%) for 10 - 15 minutes OR until the koi shows signs of distress – whichever is the shorter.


Warning. Must never be used with Formalin or Anaesthsetics.


Acriflavine and Acriflavine derivates


Great non-aggressive treatment for bacterial disease, and like potassium and chloramine, cleans up external wounds very well, and can be used with salt. One of the only recognised cures for dropsy when used in conjunction with salt. May be safely overdosed, and whilst at high strengths it will affect your filter, it will not harm your fish. Super one hit treatment for all Protozoa, Costia, Trichodena, Chilodonella and Whitespot when used in conjunction with salt. Unfortunately due to legislation, Acriflavine in liquid form can only be sold at a maximum 2% strength solution. For this reason, to be effective, it must usually be used at a much higher strength than recommended - we use it at least 10 x stronger dosage than recommended. But here you will have to make your own decision.....!


Dose – Liquid form use as per manufacturers' recommendations - or.... For Dropsy use at least 10 x strength with Salt at 1 ounce per gallon. As powder use at 3 - 5gm per 220 gallons. .


Proflavine Hemisulphate


Excellent bactericide can be used with salt and, like Acriflavine non-aggressive. Acts systemically, (internally) unlike the drugs above, and can therefore be effective against septicemia and internal infections, including dropsy. Ideal treatment therefore where antibiotics cannot be used. Like Acriflavine can be overdosed without harming your koi. Its only drawback is it’s cost and it is therefore ideal for hospital tanks and quarantine systems.


Dose – 4.5gm per 1000 gallons. Use with Salt at ¾ ounce (0,50%) for best results and at temperatures over 16 Deg. C. Repeat treatment every seven days or until symptoms improve. Complete 25% water changes between treatments. .




Used by the Japanese for many years but strangely little used in the UK. Excellent mild fungicide and bactericide. Ideal treatment to help prevent cross infection, for transporting fish and can be used with salt. Great de-stressor, non-aggressive and can be used as a dip and overdosed with safety. Perfect treatment to be used as a gill wash and therefore is much used for helping newly imported koi recover from their journey. Great alternative to Malachite and much less aggressive. Again the only drawback is the cost.


Dose – As a long term pond treatment for stress – 5gm to 10gm per ton (220 gallons). To help prevent cross infection in the pond 10gm per ton. As a dip and gill wash – 20 gm. per ton (220 gallons) for 30 minutes with good aeration. Mix with warm water and use immediately. Switch off UV.  


Tea Tree Oil


Sold as Melafix, a natural product – not a drug, excellent for curing surface ulcers on our koi, can be used with salt, can be safely overdosed and does not affect filters and therefore helps keep water quality in peak condition. Once again the only drawback is its relatively high cost. Therefore ideal for hospital tanks and quarantine systems.


Dose as per manufacturers' instructions. Use over 16 Deg. C with salt at ½ ounce per gallon for best results. Switch off UV.  




A completely natural product, a bi-product of honey production and used by bees to line the inside of the hive. Reputed to be natures own perfect antibiotic and it is claimed that bacteria cannot become resistant to Propolis. Has actually been used in human health since Roman times and is still used today in dentistry in certain countries to treat mouth ulcers. Also used to treat skin problems and can be found in a cream as well as in a liquid form. Used by koi keepers as a food additive (some foods are now including Propolis in their standard recipes). When used in this form helps to boost the koi’s own immune system, and therefore their disease resistance. Can also be used to treat ulcers directly, and is an ideal topical treatment to clean and treat wounds. One of the best topical treatments available today (just look at it’s uses through history) and will stick to Mucus and wet koi like you have never seen. Excellent treatment for mouth ulcers, and round the eyes and gills where you would not want to use nasty chemicals. Try pouring a little into a dry glass jar, leave for a few seconds, and then try washing it off! Even if you use soap and warm water a residue can normally plainly be seen sticking to even the smoothest container. A zillion times better as a topical treatment in our humble view than most of the bottled junk available today. If you don’t like using it on your koi you can add it to your tea! It will probably increase your sex life by a good ten years!!


Propolis is another one of the great products the bees produce that science cannot. It is a resinous substance that the bees gather from tree leaves and bark, and combine with nectar, wax, pollen, and bee bread to make a natural "glue" type substance. This glue is used to seal cracks and holes and to line the inside of the hive It is also placed at the entrance to the beehive, where incoming worker bees have to brush up against it as they enter the hive. This sterilises the bees from infection, and may disinfect them upon entry as well. Beehives are more sterile than the most modern hospitals.


Propolis is also used to line the birthing chamber where the queen lays her eggs, thereby providing a clean, sterile environment for the developing eggs.


Propolis contains all the known vitamins except for vitamin K. Of all the fourteen minerals the human body requires for normal function, propolis contains all but one, sulphur. It contains a number of unidentifiable compounds that create a perfectly balanced food substance. It also has 16 amino acids that have been identified, and more bioflavanoids (necessary for anti-inflammatory action within the human body) than found in oranges. It is antibacterial, antiviral, antioxidant, antifungal, and anti-inflammatory.


This substance has been used throughout the centuries for its natural antibiotic capabilities. Propolis is still able to effectively combat bacterial strains which have become resistant to modern synthetic antibiotics. The bee is the only insect ever to have been found to be bacteria free, due to the action of the propolis, and science believe that no known bacteria can form a resistance to propolis.


Propolis has no known side effects. It boosts the immune system while fighting invading pathogens, something prescription antibiotics cannot. It also has demonstrated a remarkable ability to disable viruses. When prescription antibiotics must be used, propolis has proven to boost the effectiveness of the prescription, while helping to drastically reduce recovery times in human medicine.


Propolis is still given to patients in Russia before and after surgery to aid in healing and prevent infection, and to boost energy levels during the recovery process. It is often mixed with garlic to make a powerful infection fighter, killing viruses and bacterial invaders without harming the beneficial bacteria needed by the body to function properly.


The bioflavanoids in propolis make it a superb anti-inflammatory. It also enables it to be so effective in boosting the body’s own immune system. Propolis is very useful in treating allergies, ulcers, skin ailments (internal and external), cancers, infections of all sorts, colds, flu, bronchitis, ear problems, gum disease, headaches, acne, sunburn, respiratory problems, fatigue, sore throats, skin diseases, and even Parkinson's disease, according to extensive European studies. It is still used extensively in dentistry in parts of Europe as a most effective mouth wash


Propolis is a safe diet supplement, producing no negative side effects, and taken regularly can actually create a positive reaction to almost any disease. In today's world where antibiotics are routinely over-prescribed, this natural product can be your very best first line of defence against illness and chronic diseases.


 For your koi use Propolis:-


  •  As a topical treatment for ulcers, sores, raised scales, especially useful round the mouth, eyes and gill area where the use of other medications would be inappropriate and even dangerous.
  •  As a food additive, mix one teaspoon full of propolis with approx 2 – 3 handfulls of food and a little warmed water in a suitable container. Leave to stand for 15 minutes or so or until the food has absorbed all the liquid and feed to your koi. Use all food treated in this way within 48 hours.
  •  Propolis will still work at lower temperatures, but for best results use at temperatures in excess of 13 deg C.
  •  Propolis is available in 100ml, 250ml and 500ml bottles and a 60ml spray.
  • Shake well before use.

Dose – As a food additive – mix 1 teaspoon with a little warmed water and then add approx. ½ kilo food. Leave to soak for 15 minutes before use. Do not store food when treated for longer than 48 hours before use. Store in Fridge – keep cool.


As a topical treatment - First clean the area to be treated with Hydrogen Peroxide, Potassium Permanganate or your favourite cleaner - then apply Propolis neat to the area with a cotton bud or similar, or use the spray versions now available.


Water Hardness and Osmoregulation


The hardness of water is related to the dissolved minerals it contains. The total hardness is usually regarded as consisting of two components: general hardness (GH) and carbonate hardness (KH). General hardness is caused by divalent metal ions, primarily calcium and magnesium. Carbonate hardness is due primarily to carbonate/bicarbonate ions, and represents the main 'buffering capacity' of the water, i.e. its ability to resist pH changes. KH and pH are therefore inter-related: if KH is high, the pH will be very stable (and difficult to alter), if KH is low (e.g. less than 3 degrees KH) then the pH will be less stable. and therefore low KH is to be avoided because of the possibility of pH fluctuation, which in itself can severely stress Koi.


Carbonate hardness is sometimes referred to as 'temporary' hardness, or Alkalinity because it can be removed by boiling, which precipitates the carbonates. The remaining hardness contributed by other salts of calcium and magnesium is then referred to as General hardness.


Note that a confusing number of units have been used to refer to hardness values, including different English, American, German and French degrees of hardness! (see table below)


Our Koi use the process of osmoregulation to transfer water and mineral salts contained in the pond water via the gill. The process of osmoregulation relates to the phenomena of a weaker solution moving across a semi permeable membrane (the gill) to a stronger one. Here the pond water is the weaker solution, and the fluid level in the body of the Koi is the stronger one. Koi and freshwater fish generally excrete water + salts from their body via the urine at up to 30% of their body weight per day in order to balance the fluid levels in their bodies. This process of osmoregulation is controlled by the kidneys. Koi also remove ammonia and carbon dioxide from their bodies via the gill, back into the water, so it can be seen how vital this transfer of water, minerals and gases in and out of the body is to our Koi. If the kidneys of our Koi fail or become infected, the Koi lose the ability to osmoregulate and their bodies can fill up with fluid and this can give rise to the condition we call Dropsy.


There are higher levels of mineral salts present in harder water, so the process of osmoregulation is easier for the Koi to manage - since there is less of a differential between the concentration of salts in the pond water and the fluid inside the body of our Koi. As the pond water becomes softer (and contains less mineral salts) the pond water becomes a "weaker" solution and the Koi has to work harder to osmoregulate and expel fluids from its body. In turn this means that the Kidneys are working harder and this can put the Koi under stress and more at risk from disease.


It is recommended that the KH and GH levels in our ponds are kept at a minimum of 6 degrees of German hardness or 100 mg/litre of dissolved salts.


Increasing Calcium hardness is normally fairly easy. Adding calcium based minerals such as Oyster shell to the water which will gradually leach hardening salts is one way. Specialised minerals are now commercially available and can also be used effectively.


Now you can also increase the General hardness of pond water by using specialised mineral salts, containing both Calcium and magnesium salts.


Note that normal table salt (sodium chloride), does not increase hardness. Although it will increase the overall mineral content of the water, it is not a hardening salt, like the salts of calcium and magnesium.   .



Water Hardness: Terms and Conversion mg/l CaCO3 German Degrees of Hardness Described as
0-50 0-3 soft
50-100 3-6 fairly soft
100-200 6-12 slightly hard
200-300 12-18 moderately hard
300-540 18-30 hard
Above 540 30 Plus very hard
1 degree of hardness = approx 18 mg/l CaCO3   



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