Koi Treatment: Bacterial Ulcers

Koi Treatment: Bacterial Ulcers

An ulcer is usually a bacterial infection to the skin surface that has broken through the armor of the scale. It could be in the epidermis and even deeper all the way down to the muscle. The external enzymes that bacteria produce dissolve nutrients into a form that can be absorbed through the cell walls. In other words, the bacteria are “eating” the nutrients in the fish’s body, causing tissue damage and ulcers. Septicemia, or blood poisoning, can even occur if the damage is severe enough.

Preventing disease is always better than treating for it. If your koi continuously get ulcers, then you need to change something in your water gardening habits. Regularly cleaning filtration, keeping water quality up, quarantining new additions, feeding high quality foods, and avoiding overstocking all contribute to disease prevention. Not keeping up with any of these could be asking for disaster.

Bacterial pathogens require a source, a mode of transmission, entry, and a susceptible host. While bacterial pathogens are consistently present in water gardens, they do not have to exist in large quantities. Keeping the bottom of the pond free from debris and gravel as well as regularly maintaining filtration pads can reduce the amount of nutrients available for the bacterial pathogens to feed on, thereby reducing the number of them living in your pond. Other ways to prevent large numbers of pathogens are UV sterilizers, chemical filter media, water changes, and, of course, quarantining sick koi.

Chances of bacterial infection are increased when the slime coat of the fish has deteriorated. Buying dechlorinators with added slime coat protection, maintaining pristine water conditions, and feeding high quality foods can help preserve the fish’s slime coating. This prevents the disease. AquaLife Complete is the best water conditioner and slime coat product on the market. Koi foods from OSI and AqualLife Select will ensure koi have the best nutrition.

Recovery from an ulcer is possible, but full recovery depends on the developmental stage of the ulcer. The sooner you treat, the better. Results vary on the full return of scales and color. Younger koi are more likely than adults to avoid permanent scarring.

Debriding (removal of foreign matter from the wound and surgical excision of dead or contaminated tissue) with a swab, tweezers, scalpel, or scissors is one of the steps involved in ulcer treatment. This is usually done in conjunction with hydrogen peroxide, potassium permanganate, or other disinfecting chemicals. Be careful not to get these on the gills of the fish. It is a good idea to seal the wound after treatment, though success rates vary. Bio Bandage and many dip products will help such as Bacta Dip by AquaLife. Feeding medicated foods or foods treated with medications should also help. Treatments with Nitofurazone and Kanamycin have also proven to be effective when combined with cleaning of the wounds.

In most cases, the wound should be cleaned only once to avoid disturbing the healing process and accidentally removing regenerating tissue. A whitish color is a good sign that healing is occurring.

Water quality is, of course, vital during treatment. Warmer temperatures and salt can also serve to decrease stress, increase recovery chances, and reduce bacterial pathogens.

Source: Phillips, Dan. “Practical Guide to Treating Bacterial Ulcers on Koi.” Koi USA. Volume 31, Issue 3, November/December 2006, p. 52.

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