Identifying and Treating Koi diseases
Koi diseases and illnesses can in large part be avoided by maintaining good conditions in your pond. Diseased fish are often stressed fish and koi are no exception. Knowing the signs of ill health in koi will help to treat any problems before they get worse and kill your fish.
If your fish are getting ill, conditions in your pond may be less than ideal. The main proponents of stress in koi fish are high ammonia and low oxygen levels in the water, erratic water temperatures, crowding, and parasites. One or a combination of these factors for a prolonged time may make then increasingly susceptible to common koi diseases.
Other conditions that may cause the type of stress that aggravates koi diseases in your fish are improper handling and/or moving fish, water quality, crowding , toxic chemicals, chloramines, oak blossoms, weed spray, sharp edges in the pond and poor feeding.
What types of illnesses affect koi? Koi diseases can be categorized into four categories. They may be bacterial, viral, fungal, and parasitic in nature or origin. Bacterial diseases include fin and tail rot and hole-in-the-side. When a fish contracts a bacterial infection these bacteria eat away at the skin and leave the fish vulnerable to even more diseases.
If your fish has hole-in-the-side its scales will stand on end and eventually fall off. The skin that was protected by the scales then begins to peel and leaves the fish looking as if it has a gaping hole in its body. Bacterial koi diseases are treated using acriflavin, nitrofurans, oxytetracycline, kanamycin, chloramphenicol, sulfanomides, salt either as a dip, topical, injection, or in their food.
Parasitic koi diseases are probably the most dangerous and should be treated right away. Parasitic diseases include fish lice, gill maggots, and anchor worm. These are treated by external swabbing, dips, baths, keeping them in a sick tank, placing drugs in their food or by injection.
It is critical that you treat your fish at the first signs of disease. Koi diseases are easily spread to other fish and could destroy all your stock and make conditions undesirable for new fish. If you care for your koi and their environment properly most diseases can be avoided.
This is partly because your fish will have healthy immune systems and partly due to healthy conditions that don't support the growth of bacteria or parasites. However, there are instances of fish developing koi diseases even in the cleanest environments. It is a good idea to consult experts to correctly diagnose problems in your fish.
Always check any new additions to your pond for signs of koi diseases that may spread to your existing fish. If in doubt, don't add them to your pond. Two books you may find helpful are: Handbook on Drugs and Chemicals Used in the Treatment of Fish Diseases" by Nelson Herwig and Koi Health and Disease by Erik Johnson D.V.M. - also try The Manual of Fish Health from Tetra Press.
