tiger barb disease

Question
Hi Nick.   I have had aquariums for years and have dealt with a number of disease issues. I am experiencing something new however that i cannot find any info on.  I have a 55 gal tank with a few tiger barbs, a gold gourami, a rainbow shark, a couple cherry barbs, a pleco, a couple picus cats, and 3 giant danios.  I have noticed that the danios have came from the store with a mouth disease that looks more like a small white growth than a fungus but i could be wrong. Having a hard time getting that under control. Then i noticed that my tiger barbs were getting deformities of their mouth cavities that eventually gets them resembling the scary mask in the movie scream.  It sort of looks like a thickening of the lining or something that causes deformity until they can no longer eat and starve to death. The danios dont seem to progress this way or much at all. This isnt a fast progressing thing which makes it even more alarming.  Have you ever seen or heard of such a thing?  The other fish in the tank do not seem to be susseptable or just lucky i guess. PLEASE HELP!!

Answer
Hello Lori!

Yes, I have heard of this disease, and I am very surprised that you have not. It is easily one of the most common freshwater fish diseases, probably second next to ich, and it easily curable if caught early.

It is called columnaris, or mouth fungus. Caused by poor water quality and stress. It is not really a fungus, but a bacterial infection of the mouth and mouth area. The symptoms you described are textbook examples of mouth fungus.

There are many cures for mouth fungus. Early on you can use MelaFix+PimaFix, but as it gets most developed you will have to quarentine the effected fish and use an antibiotic. The ingredient you are looking for is Terramycin, or, ideally Erythromycin. The latter being preffered.

There are dozens of treatments, but my favourite is using Maracyn 1, it has the most concentrated amounts of Erythromycin, while not being overly powerful. It's very cheap too. Probably only around $6-$10.

Oh, and also, your danios should be in a school of at least 6, and the tiger barbs should be in a group of at least 15. This stress from being in soo small a school is likely what caused the disease in the first place. When one gets it, they all do.

Also, be careful if treating your cats, they don't take too well to meds.

-Nick