Description

Symptoms: cottony patches around the mouth, white spots on mouth, whitish marks on the body and fins, the scales often appear to have white edges which is due to the cotton wool-like accumulations of bacteria. May be accompanied by clear stringy feces, a loss of appetite, and rapid gilling where gills are infected.

It is often called Mouth Fungus because it looks like a fungus attack of the mouth. It is actually caused from the bacterium Flavobacterium columnare, previously called Flexibacter columnaris, Bacillus columnaris, Chondrococcus columnaris, and Cytophaga columnaris. This is a common bacterial infection that affects freshwater aquarium fish, particularly livebearing fish and catfish. It is not seen in marine fish, they can be infected by myxobacterial diseases that are similar to columnaris, yet this is very uncommon in the aquarium.

Columnaris can enter the fish through the gills, mouth, or small wounds on the skin and results in an internal or external infection. It can have either a chronic progression of days or months or an acute progression with lesions spreading quickly, often wiping out whole populations of fish in just a few hours. It is highly contagious and may be spread through contaminated nets, specimen containers, and even food.

This disease is brought on by stress, injury, inadequate diet, and poor water quality, including an unstable pH. To prevent Columnaris maintain your water with good biological filtration and weekly water changes that include vacuuming the substrate. Keep the tank well aerated, provide your fish with a varied diet, and don't overstock.

Columnaris generally shows up first as a gray or white line around the lips and later as short tufts sprouting from the mouth like fungus. This bacterium produces protein and cartilage degrading enzymes that eat away at the fish and forms round or oval shapes with an open ulcer in the center. It may affect the fins, beginning with degradation at the edges, or as a lesion near the dorsal fin. The "saddleback" condition is a discolored gray patchy area near the dorsal fin and a pale white band encircling the body of the fish. A yellowish-brown ulcer develops in the center as it progresses. This coloring is caused by detritus particles trapped in the slime produced by thebacteria.

This is a quick acting disease and needs immediate treatment. The toxins produced and the inability to eat will be fatal unless treated at an early stage. This bacteria is often accompanied by a second infection of an Aeromonas bacteria and fungus often invades the affected skin. Be aware that some strains of this bacteria are becoming resistant to antibiotics. So ensure you treat for the full length of the medication.

Treatment

For the duration of use, any activated carbon should be removed from the filter. Switch off any UV-C appliances and CO₂ fertilizing appliances. Please also ensure that skimmers and ozonisers are switched off. 50 % of the water should be changed prior to application of medication. Aerate the aquarium using a diaphragm pump with air stone during the treatment. Feed the fish sparingly during the treatment. Because many of the pathogenic bacteria are able to survive in the filter media, we recommend a thorough cleaning of the filter or even a replacement of the filter media.

To rid the aquarium and fish of this disease, first increase the water quality and then begin treatment.

You can treat Columnaris with a gram-negative medication. However, other bacteria that are gram positive mimic the Columnaris Disease, so if you use a gram positive treatment and it worked, the affliction was NOT Columnaris disease. Some aquarists suggest using both the gram positive and negative together just in case you are not sure.

Several types of antibiotics and medications can be used to treat Columnaris:

• Penicillin: at 10,000 units per liter is a very effective treatment. Treat with a second dose in two days.
• Chloromycetin: You can use chloromycetin, 10 to 20 mg per liter, with a second dose in two days.
• Kanacyn (kanamycin): Kanacyn will treat both bacteria at once.
• Maracyn (erythromycin): Maracyn is effective against Columnaris, and using Maracyn 2 (minocycline) in conjunction with it will treat the Aeromonas bacteria as well.
• Others: Copper sulphate, Furan, Tetracycline, and Potassium permanganate. Nifurpirinol, Acriflavine, Chloramphenicol and Malachite green are also said to be effective.
• Medicated Foods: Feeding food dosed with Terramycin (Oxytetracycline) will help to internally treat this disease.

After the treatment

After the treatment, please filter the aquarium water for 24 hours using activated carbon to remove the residues of medication. Afterwards the activated carbon should be duly discarded. The addition of a bacterial starter to the aquarium water helps to replace any purifying bacteria which may have been affected. During the treatment and daily in the first days after the treatment please check the ammonium/ ammonia and nitrite values. With nitrite values of over 0.5 mg/l an immediate water change of 50% should be carried out and a bacterial starter added.