Columnaris is a bacterial infection of the fish which is caused by the Flexibacter Columnaris bacteria. This type of infection is often mistaken for a fungal infection. Catfish and other cultured fishes are those that are infected with Columnaris. Fishes that are stressed a lot with their environment are those that get easily infected by Columnaris. Fishes that live in bad quality water, improper handling and shipping, and that have inadequate diet will be affected by Flexibacter Columnaris. This disease will easily spread to the other fishes as it is contagious. Food, the container in which they have been and the nets are those that might pass on this disease to other fishes.

The way in which Columnaris affects could be acute or chronic. In the acute cases of Columnaris it would spread so quickly that the entire population would be affected and all of them would be dead in a few hours. If the temperature of the water is high the disease will spread very quickly. In the chronic cases of the infections the progression of the infection is slow and might take a few days for the fish to die.

You can identify the infection the fish by Columnaris if you see white spots on the scales of the fish. The mouth of the fish is also infected and you can find some white cotton like growth on the mouth. The edges of the fins would also disintegrate if the infections are found. Once the fish is infected with Columnaris other infections like the fungal infections are also possible in the skin. If the gills are infected by Columnaris gill flapping will be faster. This is due to the difficulty the fish faces in breathing. Sometimes you can also find lesions on the dorsal fins. During the initial stages of the infections you can find white spots in different areas of the body of the fish like gills, fins, scales, and the head. In the next stage the while spots become pale and then yellow or brown in color as the lesion develops. A saddle like appearance is seen if the infections are on the top of the fish. External symptoms are seen mostly than the internal symptoms.

There are many treatments available for the infections due to Columnaris. One of the treatments is to change the water in the aquarium. You can also add salt to the water as a part of the treatment. This form of treatment will improve the gill functions of the fish. Take precautions while treating catfish with this method as it is very sensitive to salt. For the external infections treating the fish with chemicals like copper sulfate is also done. Using antibiotics like Terramycin, Acriflavine and Furan in the treatment of Columnaris is also effective.

As with the saying '''prevention is better than cure''', it is better to know how to prevent the infections of Columnaris instead of spending your valuable time in treating this disease. Good quality of water in the aquarium is one of the effective methods to prevent infection of Columnaris. Give a good diet for the fishes and do not add any new fish before isolating them for about 15 days. All the equipments and the accessories that come in contact with your fishes should be disinfected regularly.