Columnaris (i was way off)
Columnaris spp.is a simple pathogenic gram negative bacteria. It is commonly found in soil, water and on healthy and sick fish.Its 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.
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 thru the air to another tank, more likely by equipment and a persons own hands during cleaning. But is still does not spread to all fish in the tank if the tank is cleaned, regularly water changes, no stress conditions , and plenty of dissolved oxygen. Its numbers would still have to be great to over come a healthy fishes immune system.
IMO and IME 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. Heres 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 speed up the reproduction of bacteria. Higher temps 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 info you can find. Its not the dreaded disease its been made out to be on these forums. Its preventable, and treatable if contracted and recognized. Quaranteens are extremely useful as its 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..
so what do you use to treat it ?
1) potassium permanganate is highly effective as a dip and tank treatment.
2) Doxycycline and tetra cycle work well also, but will trash bio filters and should be used sparingly to prevent resistent strain from forming.
3) High salt concentrations, as in 1 tablespoon / 1 gal water... watch the fish for signs of stress, and cutback the salt if you see any. salt does not kill columnaris , but it can slow it down significantly.
4)Water changes... The more water you remove the more bacteria you theoretically remove. Concentrate on cleanliness. Columnaris is a substrate bacteria, it thrives on foods and feces.
5) Increase aeration.... most severe out breaks occur in low oxygen waters.... Avoid increasing water temp, its like adding miracle grow to a weed.
6) do not use a cocktail med. Shot gun medications cause far more harm than good.... A good specific Gram negative antibiotic should be used , and all direction followed. Resistence to meds is a growing problem. It comes from using the wrong meds for the wrong time course.