ULCER DISEASE OF GOLDFISH & KOI

True "Ulcer disease" of goldfish is now accepted as being caused primarily by Aeromonas salmonicida, the same organism that causes furunculosis in rainbow trout and salmon. A carrier state exists in recovered fish, which when stressed can release infectious organisms into the water. These can then attack healthy fish in the same body of water, particularly those under stress or with any skin damage eg. caused by clumsy netting. The causal organism is shed from carriers at times of stress such as spawning, handling, high temperatures, and sudden changes in environmental conditions. A wide range of other organisms may be associated with ulcers in goldfish and koi. Aeromonas hydrophila is a common isolate, as are Flavobacterium and Pseudomonas spp.

Treatment involves cleansing the ulcer thoroughly using Tamodine packing the cavity with Orabase (from Boots) then the fish is best held in a salt bath (5g/litre). One treatment is often sufficient, repeated cleansing simply disturbs the healing and prevents the skin covering the deficit. Water can be treated with Chloramine-T periodically to control bacterial levels.

Use of supplements high in vitamins A, C and E, ie. ACE-High from Vetark during the treatment period (and prior to periods of prolonged fast such as overwinter is very important in preparing fish for this period of semi-hibernation).

-The misuse of antibiotics by fishkeepers has produced resistant strains of many fish bacteria. Injections are of value in treating certain cases; short term (1-4 hour) baths are also used but are of uncertain value in many cases. -Various antimicrobial agents have been used but efficacy will depend on resistance, the stage of the disease and the overall condition of the fish under treatment.

This is a much safer and preferable alternative to the topical use of malachite green or mercurochrome. Both of these are toxic to cells and will often simply kill a new layer of tissue each time an ulcer is dressed, the mercurochrome may even cause systemic toxicity.

Care must be taken with nets to avoid transmitting disease between batches, netting a fish with an ulcer contaminates the net, and then when used again the net rubs the organisms into the skin of another fish. Disinfection of nets using Ark-Klens is well worthwhile since it is also a detergent and lifts mucus off which might protect bacteria from the effects of a disinfectant. More serious disinfection against SVC calls for use of Tamodine-E in net baths, foot baths etc.

EXCESSIVELY FREQUENT DRESSING OF ULCERS SIMPLY DISTURBS EPITHELIALISATION AND HINDERS HEALING, IN MOST CASES A SINGLE TREATMENT AS DESCRIBED ABOVE IS SUFFICIENT