Bacteria are microscopic, single cell organisms that can multiply very rapidly when the conditions are right
. They gain access to the koi orally, for example through contaminated food, or via the gills or open wounds. If they become established in a wound and prompt topical treatment is not administered, the problem may become systemic and require antibiotic treatment.
Bear in mind that in some countries antibiotics can only be obtained legally via a veterinary prescription. They are the two bacteria most commonly found in a koi fish. Affected fish may exhibit reddening of the skin around wounds, for example. When established systemically, bacteria can cause swelling of the body cavity.
This results in raised or protruding scales and possibly protrusion of the eyes. The condition is often called dropsy and requires prompt antibiotic treatment to prevent further spread and potential death. When a bacterium affects the gills, it is generally described as bacterial gill disease.
Before using antibiotics to treat a bacterial infection, it is necessary to identify the bacteria present and the antibiotic that is most effective against it. A swab is taken from the infected area and sent to a laboratory for cultivation. Sensitivity to particular antibiotics is tested.
Based on that information, obtain a medicated food or administer the antibiotic by injection. Both topical treatment of wounds and injection procedure will require an aesthesia. A koi fish exhibits the symptoms of abdominal dropsy and pop eye. The body has swollen to the point where the scales cannot stay flat; this is often described as pinecone. The pressure exerted by this excess internal fluid is noticeably pushing out the eyes.