Flexibacter columnaris bacteria are gram-negative.  The fish will exhibit a fuzziness or cloudiness in its scales and fins.  When this disease attacks the fins, the soft tissue of the fins will disintegrate, leaving only the fin rays.  Quite often, the skin and gills will become infected by a secondary bacterial or fungal invader.  When this disease affects the gills, it is called bacterial gill rot.  If the disease is allowed to reach the gills, it is almost too late to save the fish as the response from the fish is to secrete extra mucus upon the gills.  This has the  effect of suffocating the fish.  A similar infection of the mouth is seen in the livebearers and other fish and is called mouth rot.  It is often incorrectly called mouth fungus.  The best course of treatment is to use nitrofuranzone at a dosage of 30 to 90 mg (active ingredient) per 2.6 gallons (10L) of water.