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Michaels Fish Room

Columnaris Treatment

Columnaris Treatment

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Regular price $14.99
Regular price Sale price $14.99
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What is Columnaris

Before we can use a columnaris treatment, we must know what we are dealing with! Columnaris (also referred to as cottonmouth) is a symptom of disease in fish that results from an infection caused by the Gram-negative, aerobic, rod-shaped bacterium Flavobacterium columnare. It was previously known as Bacillus columnaris, Chondrococcus columnaris, Cytophaga columnaris, and Flexibacter columnaris. The bacteria are ubiquitous in freshwater, and cultured fish reared in ponds or raceways are the primary concern – with the disease most prevalent in air temperatures above 12–14 °C. It is often mistaken for a fungal infection. The disease is highly contagious and the outcome is often fatal. It is not zoonotic.


Columnaris is a deadly and fast-moving infection that can wipe out an entire tank if not treated correctly and swiftly! Here at Michael's Fish Room we have tested many types of columnaris treatment and found Salt and Methylene Blue to be the most effective. See the video here.


  1. Turn off the heater and lower water temp to room temp. (68-72F)
  2. Do a 50% water change.
  3. If you use a water conditioner like Prime or Fritz Complete, wait 30 to 45 minutes before adding treatment.
  4. Add the salt and methylene blue to the tank.
  5. Wait for 7 to 10 days with no water changes.
  6. After 7 to 10 days do a 50% water change and check fish to be sure the Columnaris is cured.
  7. If it is not cured, a 2nd treatment may be needed at 50% of the original amount dosed and wait for another 5 to 7 days.
  8. If no sign of Columnaris, leave the 50% salt and meth blue in the tank until your next water change time. Doing 50% water changes at normal water change times until the blue is gone. Or you can add activated carbon media to a filter to remove the blue color from the water.

What is Included

Included in your purchase is the proper dose of aquarium-safe salt and methylene blue to treat up to a 10 gallon tank. Multiple doses can be added for larger tanks.


Most plants, some snails, and some fish cannot handle the amount of salt in this treatment. It is your responsibility to make sure other fish can handle the treatment. This treatment could kill your beneficial bacteria. It may also stain light-colored items in the tank a light blue color. (sand, decor, silicone seams) Treatment has been tested on these fish only: Guppies, Platys, Swords, Mollies, and Bristle Nose Plecos.

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