Koi Ulcer Remedy

If you keep koi, otherwise known as Japanese carp, you have probably grown to treasure these brilliantly-colored, graceful fish, and understand why they have long been revered as symbols of love and friendship. If one or more of your koi has developed ulcers, it is important to act quickly to treat the infection. By correcting the water quality and giving the proper medication, you can restore your ornamental koi to their customary beauty and health.

  1. Koi Ulcer Features

    • Koi ulcers are holes that develop on the exterior of a fish--usually on the flanks or underbelly--caused by infection by the aeromonas bacteria, which in turn follows infestation by a parasite. Ulcers can also be caused by abrasions and scratches that have penetrated the fish's protective slime coat. They are found more frequently in the spring, when the koi's immune system is at its weakest, and in fish that have been resting on a pond bottom that is excessively rough, causing a "bed-sore" type of ulcer. Koi ulcers usually begin as a single raised, reddish scale, and then develop into open wounds that become progressively deeper and larger. Ulcers on your koi are usually an indication of poor water quality, which must be corrected in order for the fish to be able to heal.

    Water Quality

    • The main cause of fish becoming susceptible to parasites and bacterial infection is poor water quality. Prevent ulcers and maintain your koi in optimal health by keeping your pond well-planted with both marginal and surface plants, which aid water quality by absorbing dangerous ammonia and nitrites, as well as adding oxygen.

      Use a biofilter containing beneficial aerobic bacteria to further purify waste products in the water. Replace the filter as needed as your koi grow larger. To maintain the health of the aerobic bacteria, keep the filter running around the clock. To reduce teh amount of waste left from feeding your koi, use a high-quality commercial fish food with low ash levels, and offer small, frequent feedings.

      Be alert for fish gasping at the surface as a symptom of poor water quality; at the first sign of this behavior, stop feeding and test the water for ammonia and nitrite. Protect water quality further by pumping out small quantities and replenishing with fresh water on a weekly basis. To prevent build-up of rotting organic debris, vacuum the bottom of the pond frequently.

    Treatments

    • To cure your koi of ulcers, you must not only correct poor water quality, but treat for parasites and bacteria. Use pond salt, added at a rate of 1 and 1/2 ounces per ten gallons, as a natural antibacterial agent. You can also treat your fish with commercial fish foods that contain antibiotics.

      According to the Koi Ulcer website, it is safe to give a one-time-only treatment to your koi's ulcer by gently netting the fish and cleaning the ulcer with hydrogen peroxide on a cotton swab (see Reference 3). Severe or very large ulcers may require that the fish be anesthetized and injected with medication; unless you have experience treating koi ulcers in this way, you should enlist the help of a veterinarian.