Potassium Permanganate For The Treatment Of External Infections Of Fish

Day 11/05/2021

Usually, KMnO4 can be used at a concentration of 2 mg/L as a long-term bath (minimum 4 hours) in fresh or salt water system of fish. Fish culturists should run a small bioassay before treating the fish with KMnO4.

Some fish, including certain lake cichlids, are sensitive to KMnO4 and lower concentrations (1 mg/L) may be safer. Fish farmer may know the species sensitivity by seeing the behaviour of fish during treatment. This is especially important when treating a species for the first time.

If fish react adversely, immediate action (e.g., diluting KMnO4 with freshwater) should be taken. Because KMnO4 is deactivated by organic matter, it may be necessary to increase the amount added to ponds or other systems where organic material has been allowed to accumulate.

A safe way of doing this is to add KMnO4 to the system in 2 mg/L increments. If water colour changes from purple to brown in less than 4 hours from the start of the first treatment, an additional 2 mg/L should be added. If a total application of 6 mg/L KMnO4 does not result in maintenance of the purple colour for at least 4 hours, the system should be cleaned.

Most of the organisms that are treated with KMnO4 thrive in an organically rich environment; so the improved sanitation can have a tremendous impact on treatment efficacy.

Precautions When Using Potassium Permanganate

A few helpful reminders and precautions before using potassium permanganate include:
• Be sure you have a problem that warrants treatment.

• Potassium permanganate is a strong oxidizer and can burn skin, eyes, and other body parts. It will stain you and everything it touches brown. Always use safety protective gear including rubber gloves, goggles and old clothes. A dust mask is advisable to prevent irritation to your respiratory tract.

• Be sure to estimate water volume accurately, and disperse the chemical evenly over the entire pond to prevent hot spots, areas of the pond with excessive amounts of chemical.

• Potassium permanganate can kill algae. Low oxygen conditions can occur following treatment. Be prepared to aerate after treatment.

• Frequent treatment can harm fish. Wait at least four days before repeating treatment. If fish do not respond to treatment, reevaluate them to confirm the diagnosis.