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Potassium Permanganate

Keywords: Koi, Goldfish & Pond Health Potassium permanganate KMnO4 caustic alkali organics oxidizer PP for koi diseases parasites fungi

What It Is:
Potassium permanganate is a purple granular powder. It can stain your hands brown if contacted directly.

What It's Good At:
Potassium Permanganate (KMnO4) kills 99.9% of exposed pathogenic bacteria, kills most ciliate parasites, most fluke parasitisms, fungal infections and potassium permanganate oxidizes organics in the water, leaving it cleaner and fresher than before treatment.
Note: Here are some guidelines:

  1. For flukes you should treat every third or fourth day for three or four treatments.

Note: Aqua Prazi is a much safer treatment for flukes and more  effective. Does not set back your filter.


  1. For ciliate parasites you should treat every day for five treatments.

Powerful oxidizer clears many ciliated protozoans, flukes, fungi and bacterial infections. Dosage and interval are critical. Use caution and dose carefully, avoid contact with skin, eyes or mucous membranes. Bypass filter and increase aeration and circulation. Can be neutralized with dechlorinator or hydrogen peroxide. Full details with product.

There's hardly anything with such a broad spectrum and this can be used in extremely cold water.

If carelessly overdosed, it will kill your fish. In addition to waxing most exposed pathogenic bacteria, it also kills 99.9% of exposed beneficial bacteria so you're advised to avoid letting it pass through your filter.

Wear protective eyeware and keep away from children and pets.

  • Fungus
  • Ciliated protozoans
  • Trematodes/Flukes
  • Immature forms of lernea
  • Argulus
  • Bacterial ulcerations
The chemical is perfect for applications where salt will not be used, cannot be used, or should not be used, and balances perfectly where salt leaves off. While salt may spare some Trichodiniids, Flukes, fungus and bacteria, PP does not.
PP added to the system drops bacterial counts by as much as 99%, but that also includes your filter, so be sure to stop water flow through the bio filter.
Once added to the system, PP oxidizes organic material, and parasites, and bacteria, into harmless particles, and manganese dioxide, which is a brown precipitate. It is recommneded that you execute a massive waterchange and re-start the filter as soon as you let the water turn brown. That is, the water should be kept pinkl or wine colored by repeated application of PP until ten hours has elapsed, then a massive waterchange is undertaken to remove the suspended brown oxidized debris.
PP is toxic to the fish above 4 ppm and so your volume estimate should be nearly exact, or underdosage should be done, with repeat applications as necessary to keep the water pink.
For example, I have treated ponds with high organics at 4 ppm. Within 45 minutes, I had to add another 2 ppm to maintain a pink hue, and within an hour of that I had to add another 2 ppm. So, the pond took a total of 8ppm over the first ten hours, but not all at once.
As soon as the water turns brown, the filter can be re-started without feear for your bio bacteria.
PP disinfects wounds, very efeectively asnd can be used as the sole treatment for superficial infections. In cases of sepsis, where the fish is becoming generally reddened, the PP is only a useful adjunnct, and injection should be sought.

I do not recommend feeding during the treatment because the fish may ingest too much of the PP with the food particles.

Dosing 4 ppm is by adding one gram PP per hundred gallons of water.
To do slightly less, e.g. 3 ppm, then simply dose less than a gram per hundred.
The only time to dose 2 ppm is in a low crowding situation in quite clean water, as in a holding vat. 2 ppm doses are also the usual supplementa dose size, after an initial dose has been applied.
To apply the chemical, dissolve the compound in water, and then splash this around the surface of the pond, avoiding the formation of "hotspots". Do not come in direct contact withn this aggressive, staining compound.
I recommend treating at 3 ppm initially in the morning so you have all day to observe the tank or pond. Then add 2 ppm doses as needed.
Lilies are unharmed by this, as are iris and Hyacinth, all survive the treatment handily.
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