Al Sabetta April 5, 2002

Columnaris spp. is a simple pathogenic gram negative bacteria. It is commonly found in soil, water and on healthy and sick fish. It's an opportunistic bacteria attacking sickened, weakened, immuno-compromised fish. Fish that are weakened by toxic ammonia as can occur in shipping, poorly cycled tanks, overstocked tanks, poor water quality, physically damaged fish, higher temperatures, low dissolved oxygen, high pH or any combination of these.

Photo 1: White spots on skin and scale margins in a Columnaris infection.

In nature outbreaks only occur in lakes and streams during oxygen depravation times such as droughts and high temperatures of the summer months. The rest of the time it doesn't just disappear, but if the fish are healthy its not a problem.

In a tank it has the potential to spread through the air to another tank, more likely by equipment and a person's own hands during cleaning. But is still does not spread to all fish in the tank if the tank is cleaned, has regular water changes, no stress conditions, and plenty of dissolved oxygen. Its numbers would still have to be great to overcome a healthy fishes' immune system.

In my opinion and in my experience, the number one mistake people make with columnaris is they mistreat it because most don't take the time to even learn what it is. Here's the way not to treat it- jack up the temperature. Sure it works to help a fish get its immune system going a little, but it speeds up the reproduction of bacteria. Higher temperatures also decrease oxygen in the water, speed up fish metabolism and subsequent waste productions. Then start dumping in every antibacterial you can think of, stress you fish out a little more, this gives columnaris even more of a chance to multiply.

Incidentally, the more pathogenic strains thrive at pH of around 8.0. Acidic water and tannins are inhibitory, salt has been shown to inhibit its reproduction as well. It has also been shown to thrive on uneaten fish foods and wastes.

If you are really concerned about the disease, read the attached and any other information you can find. It's not the dreaded disease its been made out to be on these forums. It's preventable, and treatable if contracted and recognized. Quarantines are extremely useful as it allows you the opportunity to recognize an ACUTE infection in the fish. Acute infections can release large numbers of bacteria into the water and overwhelm other fish. You have to know what you are dealing with though in order to treat any illness.

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