Pond Fish Information » Bacterial Koi Diseases

Columnaris (Flexibacter columnaris) or Cotton Wool Disease is another bacterial infection. The common name comes from the white tufts that develop around the mouth and spread to the body and fins, often leading to ulcers and a thin appearance.

Often mistaken for a fungal infection because of its mold-like lesions, Columnaris is a common bacterial infection in cultured fish, particularly livebearing fish and catfish. Its name is derived from columnar shaped bacteria, which are present in virtually all pond environments.

The bacteria are most likely to infect fish that have been stressed by such conditions as poor water quality, inadequate diet, or handling and shipping. Columnaris can enter the fish through the gills, mouth, or via small wounds on the skin. The disease is highly contagious and may be spread through contaminated nets, specimen containers, and even food.

Treatment with anti bacterial medicine is usually effective.

Raised scales (rather like a pine cone) and eyes standing out from the head.

Dropsy itself is not a disease, but rather a result of some other cause. Dropsy is a term given to the swelling that occurs internally in the fish. There are multiple possible causes. Sometimes it's not contageous, but sick fish should be isolated and treated since determining the actual cause may be impossible, and also because this will be easier on the fish.

The fish's body will become swelled with fluid it is unable to expel. Eventually the swelling will cause the scales to raise, giving the fish what is called the "pine-cone" appearance.

Diagnosis, One of these situations may be the cause:

• Sudden swelling: A bacterial infection will cause internal bleeding.
• Slow swelling: Growing tumors, or even parasites, in the fish may cause it to swell.
• Slow swelling: Mycobacterium tuberculosis. Highly contageous!

Bacterial dropsy is infectious so treat with an anti bacterial remedy and if possible isolate affected Koi.

A number of bacteria are associated with finrot, lesions and internal hemorrhaging, notably Aeromonas and Pseudomonas. Ulcers usually start at the site of an injury, the bacteria then infect it causing further damage, and fungal infection can also occur.

Such holes result in osmoregulatory problems, leading to damaged kidneys and death if not treated. It is worth adding a weak salt solution to the pond as well as anti bacterial remedy, a concentration of 3gm per litter will help to restore the osmotic balance and reduce strain on the kidneys (make sure that the salt is fully dissolved before you add it to the pond).

Fin rot is easily noticeable, the fins and/or tail look chewed and are red at the edges. Secondary bacterial and fungal infections can develop.

This is a disease which is not difficult to treat, and fish usually will survive. Most common in the fancy varieties of goldfish and Bettas, fin rot can occur as a result of an injury, as a secondary infection once the fish has been weakened by another disease, or in some cases, as a primary infection (bacterial (Pseudomonas fluorescens) ).

Fin rot can be the result of a bacterial infection (which causes a more ragged rotting), or as a fungal infection (which rots the tail more evenly and is more likely to produce a white 'edge'). Sometimes, both types of infection are seen together. Infection is commonly brought on by bad water conditions, injury, poor diet, or outwintering fancy goldfish (who should live in warmer temperatures).

Fin rot starts at the edge of the fins, and destroys more and more tissue until it reaches the fin base. If it does reach the fin base, the fish will never be able to regenerate the lost tissue. At this point, the disease may attack the fish's body directly. This infection can happen overnight without warning.

The treatment is to do a major water change, add aquarium salt (salt without iodine, often called sea salt), and make sure that you are providing a healthy balanced diet with a lot of vitamins. Medications should be added as the main treatment.