Potassium Permanganate for Fish

Fish diseases often start as external issues. If not treated, the problem can become systemic and can prove fatal to the fish. Potassium permanganate is an effective measure to control external infectious agents before they go systemic. It is a broad spectrum treatment that eliminates many of the parasites that cause fish illness.

  1. What is Potassium Permanganate?

    • Potassium permanganate is a powerful oxidizing agent that is purchased in crystal form and has a purple color. The water turns a pinkish-purple when permanganate is added. As the chemical oxidizes, it turns brown.

    Background

    • Potassium permanganate kills ciliates, flukes, bacteria and fungi. However, it is a very caustic chemical that can be fatal to your fish if dosing is not done correctly. Permanganate also decreases the amount of organic matter in the water, improving water clarity.

    Potassium Permanganate and Fish Illness

    • This chemical is not a medication, rather it is a caustic alkaline material that is effective against many detrimental bacteria such as Costia, Trichodina and Chilodonella, all of which can be fatal to fish. It also eradicates skin and gill flukes, bacterial gill disease and skin ulcers.

    Potassium Permanganate Baths for Fish

    • A fish can be given a bath in potassium permanganate if you want to avoid exposing the entire tank to the chemical. After isolating the sick fish, you can apply a full strength swab to the affected area or dip the fish in a double strength bath for 30 minutes. Permanganate is an excellent choice to treat external wounds.

    Cautions

    • Permanganate is not to be used lightly. Overdosing a tank can lead to fish death. It is crucial to follow the dosing instructions and know the exact amount of water you are treating. Since it does not distinguish between good and bad bacteria, you should turn off your filter while treating the tank.

    Dosing Instructions

    • When dosing a tank with potassium permanganate, observation and diligence is needed to ensure the correct amount is used. The University of Florida IFAS Extension recommends 2 mg/L (milligrams per liter) for a whole tank treatment. The water should retain its pinkish-purple color for four to six hours to be considered effective. Treatment should not be repeated more than once a week.

    Personal Safety

    • Since potassium permanganate is such a strong oxidizer, caution should be used when handling the chemical. Wear rubber gloves, goggles, old clothes and a dust mask.