What is it?

It's a "fungal" infection (that is really a bacteria, but people tend to classify it as a fungus) known as flexibacter columnaris. It particularly prevalent in rainbowfish. Do a google search or search here on AC for more info.

Many of the rainbows I have/have had came with initial outbreaks of columnaris. I have successfully treated all cases of it with no casualties with Binox. It's commonly available, in powder form, very concentrated. If i recall, 1/4 tsp treats something like 20 gallons for four or five days. I dosed a little over the recommended dosage.

If possible, lower the tank temps a few degrees - very gradually - because it doesn't like the cooler temps. Keep treating until well after you think it has gone back. This has been the cause of frustration for many, myself included. You think it goes away, you stop treating, it's back. Sort of like ich.

As with anything else, keep the water clean, very low nitrates. It apparently does not do well in higher oxygen saturations, so adding an airstone may help speed the recovery.
 
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Leopardess said:
It's a "fungal" infection (that is really a bacteria, but people tend to classify it as a fungus) known as flexibacter columnaris. It particularly prevalent in rainbowfish. .
Well, thats nice to know since I was planning to stock my next tank with bows. Now I will be prepared.

That's what I love about this site, you can find info you need without even knowing you need to look for it. cool, huh?
 
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