Using PP???????

Using PP???????


Potassium Permanganate Powder
How does it work?
And what are the dangers in using it?

Jim E. Quarles
Jan 10 2000

If you keep discus I am sure sooner or later you will hear about a product called Potassium Permanganate or just P.P.

And the purpose of this article is to make it perfectly clear how pp works when used as a fish medication, and the dangers of using it without proper controls and understanding of what it does and how it does it.

MAKE NO MISTAKE potassium permanganate is a DANGEROUS SUBSTANCE. (Kmn04) It is ineffective in the presence of organic matter.

It is corrosive. And it is not a spirochaetal agent. It can be explosive. And it is a toxic compound.

Now with that said, how does it work used as a bactericide? Just what are it's physical and chemical reactions with organic matter namely in this case the external surface of a fish and any bacteria and or parasites that might be found in its environment?

Potassium Permanganate is a very strong oxygenizing agent. It's effect upon organic matter is to oxidizes it, ( if effect burn it up). It removes and breaks down organic tissue. The effect is chemically different, but you could compare it to using fire to burn up any organic matter that comes into contact with it.

When used on discus the first thing that occurs is that the slime coat is attacked and oxidized. Once that protective coating is gone, if the solution is strong enough it will then start to oxidize the finer tissues exposed to it. The gill membranes and finer fin areas are next acted upon.

If the mis-use has gone this far, the fish is doomed in any event. But next the tissue that the pp starts to oxidized is the epithelial membrane or the epithelium of the gills.

If this stage is reached you have in effect fried the external body of the fish to a point it will not survive. But far short of that damage, if in deed that has happened, the usefulness of the fish has been greatly reduced, and more than likely caused it to suffer a good deal if it lives.

The natural defenses of the discus includes the mucus layer that covers the exterior surfaces of the fish, this mucus is a moving layer of protection against parasites and bacteria. By peristaltic action the mucus is moved from head to tail and then shed into the water to be replaced by renewed mucus. Parasites and bacteria must get past this layer in order to infect the fish. Under normal conditions most if not all the parasitic agents are caught in this mucus layer and expelled from the fish's body.

Now along comes the hobbyist, and mixes up some good old, Potassium Permanganate, and in some concentration or other dumps it into the tank. Now if the object of this exercise is to burn off the mucus layer of the fish or greatly reduce it, that's fine, because that is exactly what is going to happen.

This can be a useful event in very rare cases of massive attacks by parasites on the mucus, such as is the case with Discus Plague. In the case of plague you want to strip the mucus layer and let the fish resupply a fresh coat, thereby removing a high concentration of infectious agents. The treatment is followed by placing the treated fish in new fresh parasite free water.


To some extent it has the same effect on a pathogen that it has on the mucus layer of the fish. But it should be remembered that most parasites have their own defenses against attack, that allows them to survive and complete their own life cycle. The number one defense is to encapsulate when attacked by any agent. Once the parasite has become encapsulated its defenses are far stronger and harder to penetrate or oxidize then the epithelial membrane of the fish. Also, when some parasites encapsulate they embed themselves in the membranes of the host. So that if you are able to remove even a large number of parasites, you may be setting up conditions of later infections when the encapsulated parasite once again becomes active.

A general condition that is best remembered is that using any chemical it is easier to kill or damage the host long before you can cause the total removal of a parasite.

So Should you Ever Use Potassium Permanganate?

The answer to that is a qualified yes! I can think of two reasons and conditions under which the use of pp maybe justified.

  • If and when you wish to remove the mucus layer of the fish.
  • As a pre-conditioner of water to be used in an aquarium system.

I have already explained how the pp oxidizes and causes the loss of the mucus layer of a fish.

But what about choice # 2. Preconditioning water for aquarium use? How do you do that and why?

Used in the right concentration pp will oxidize all organic matter it comes into contact with. So you can see that if used in holding water, later to be used in fish tanks, any parasite or bacteria will be burned away or killed other than those who are able to encapsulate under those conditions.

The only problem with this is that the mixture must be such that the pp becomes inert once all organic substances are removed. This is a complex problem and at best guess work unless the color of the water turns a very light brown or you have a test kit that allows you to measure any remaining pp that is active as a oxidizer.

The point being made here other than to explain how pp works and why it works is to point out it is not a cure all for everything that you see and think are effecting the health of your discus.


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