Fish Health » Disease

It is important to remember that pathogenic bacteria are always present in our water and on our fish. They are a problem only when the fish are weakened by poor water quality or parasite infestations. So, before attempting to treat a bacterial infection, be sure that you correct any underlying problems first. Symptoms can include fin and tail erosion and fraying, redness of the tail, pectoral or anal fins, and red open sores (ulcer disease).

The most effective remedy for most bacterial infections is feeding medicated food containing tetracycline, romet, or oxolinic acid for 10-14 days. Blue Ridge uses a medicated food with oxolinic acid, and it is available for purchase for store use only. Blue Ridge's medicated food is not to be resold or fed to fish intended for human consumption.

Anchorworms resemble a short piece of thread coming from beneath a single scale. Koi infected with Anchorworms very often develop ulcer sores due to the damage caused by the worms as they bury into the flesh of the fish. Be aware that anchor worms will not disappear immediately. The treatment may take a week or longer, according to the water temperature.

Use treatment #4.

Is an unsightly but relatively harmless virus seen occasionally on koi. It has a waxy white appearance. It's mostly seen in colder water temperatures and will many times dissapear as the water warms.

Like costia, chilodonella are microscopic. They are most usually present in colder water (40-50 degrees). Symptoms are similar to those caused by costia.

Treatment options in order of preference are #2, #1, and #3.

Columnaris (Flexibacter columnaris) Disease is another bacterial infection. The common name comes from the white tufts that develop around the mouth and spread to the body and fins, often leading to ulcers and a thin appearance.

Often mistaken for a fungal infection because of its mold-like lesions, Columnaris is a common bacterial infection in cultured fish, particularly livebearing fish and catfish. Its name is derived from columnar shaped bacteria, which are present in virtually all pond environments.

The bacteria are most likely to infect fish that have been stressed by such conditions as poor water quality, inadequate diet, or handling and shipping. Columnaris can enter the fish through the gills, mouth, or via small wounds on the skin. The disease is highly contagious and may be spread through contaminated nets, specimen containers, and even food.

Treatment with anti bacterial medicine is usually effective.

Costia are microscopic parasites that attack the skin and/or gills of the fish. Symptoms include loss of appetite, listlessness, flashing, and excess slime production.

Costia normally only affects fish that have already been debilitated by some other cause, and can often be seen on Koi as a secondary parasite.

Costia is one of the many fish diseases that are caused by protozoa. It is a somewhat rare disease that is relatively easy to cure if your fish becomes infected by it. There are several treatments for this disease but it is of course preferable to prevent the protozoa from ever infecting you fish by keeping your facilities clean and your fish healthy and well fed, while at the same time doing what is possible to avoid introducing diseases and parasites into the pond.

Treatment options in order of preference are #2, #1 and #3.

Raised scales (rather like a pine cone) and eyes standing out from the head.

A sign of a number of conditions, may be congenital heart or kidney failure or an internal bacterial infection.

Bacterial dropsy is infectious so treat with an anti bacterial remedy and if possible isolate affected Koi.

Fish lice are sometimes mistaken for a small patch of green algae on the fish. After looking closer, you will see that it is a round "bug" that is a little larger than a pencil lead. As with anchor worms, fish lice make little holes in the fish, making them vulnerable to bacterial infections.

Use treatment #4.

Flukes are the most commonly found parasite on koi and goldfish. High numbers can cause serious damage. Symptoms include flashing, gasping at the surface, frayed fins, and death. Most cases of ulcer disease are preceded by fluke infestations.

Treatment options for flukes are different for koi than they are for goldfish. For goldfish, see treatments #5 or #3. For Koi use treatments #6 or #3.

Disease Text is by Randy Lefever. Thanks to Dr. Andy Goodwin for some of the pictures.

Ich (whitespot) – Ich is one of the most common and widespread of all the fish diseases. It is characterized by tiny white spots the size of coarse sand. Its microscopic stage is round with a horseshoe shaped nucleus. Symptoms may appear before you see the white spots. They include flashing (rubbing their sides against the pond), lethargy, and loss of appetite. The treatment of choice for ich is salt for 10-21 days, depending on the water temperature. Ich takes longer to clear in colder water.

Use treatment #2

Is a very contagious, damaging and deadly disease for koi, many times causing up to 90% loss in just a few days. Symptoms can include respiratory distress, hyperactivity and uncoordination, and severe gill necrosis.

It's usually seen when the water temperature is between 70 and 80 degrees. As with most viral diseases there is no known cure. Some people have had success with heat treatment to 86F, but the carrier state of the survivors is currently unknown. Goldfish are unaffected.

Like the name suggests in seen only in the spring as pond temperatures are rising. It's usually seen between 40 and 60F.

This virus is much less damaging than KHV and currently is very rare in the US. SVC produces symptoms typical of those seen with many infections and can include dropsy, hemorhages and/ or darkening of the skin.

SVC is classified as a "reportable" disease, so a confirmed diagnosis can lead to heavy handed federal government involvement.

Another microscopic parasite, trichodina is easily identifiable. It resembles a wagon wheel. Fish infected with trichodina often develop a gray film over the body in response to the infestation.

Other symptoms include flashing, lethargy, and hanging at the surface.

Treatment options in order of preference are #3 and #1

Ulcer disease is a particularly destructive bacterial disease. Seen on koi and goldfish, it starts out as a red or white pimple and quickly widens into a large hole or ulcer. It can advance all the way into the muscle of the fish. It is very important to catch this disease in its earliest stages.

Anchorworms, fish lice, and flukes can all contribute to ulcer disease. Keeping your fish clear of these parasites is very important. Keep affected fish in salted water and feed medicated food. The bath treatment Tricide-Neo can help as well. Medicated food and Tricide-Neo can be found at Koi dealers and dry goods retailers. Valuable fish can warrant antibiotic injections. Contact an experienced veterinarian for assistance.