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Chris on Koi

A Case Against Anti-Biotics?

Note: This article was first written in 1996 and published in 1997. Many experts disagreed with this article and Chris came under some harsh critism. The outbreak and first reports of of the devastating Koi Herpes Virus occurred soon after this.

“The World is unprepared for the coming plagues” says Laurie Garrett in her recently published book - The Coming Plague - which documents the fight-back microbes are making on the planet. After four decades of assuming that the conquest of infectious diseases was imminent, people on all continents now find themselves besieged. Doctors and scientists have been fighting a fifty year battle with infectious microbes. In recent years strains of TB, cholera, malaria that are resistant to all known anti-biotics and drugs have sprung up all over the world. New bugs and viruses that kill in hours have been recorded in recent years.

Bacterial infections were a common and serious problem before the first antibiotics became available in 1944. After the introduction of penicillin at the beginning of the war, a minimal dosage would perform miracles. Today massive dosages of any number of anti-biotics are needed in many cases. In those days there was very little understanding of what the tiniest microbes, viruses did to the body. There was no distinction made between bacteria and viruses. The name Ebola disease strikes fear into the hearts of anyone coming into contact with an infected person. Lassa Fever, Marburg virus, flesh eating bacteria which can literally destroy the flesh of a limb within hours, have all been documented.

Of the some 5,000 species of viruses known to exist in the world, we’ve characterised less than four percent of them. Some 2,000 bacterial species, most of them terrestrial have been characterised. There are an estimated 300,000 - 1,000,000 bacteria thought to exist. Scientists postulate that bacteria account for around 10% of all life on earth - and most of the time we are not aware of them.

In ocean water it was discovered that at low temperatures there were around 10,000 viruses per millilitre of water. At the peak of the warm summer months there were as many as a billion viruses per millilitre of water.

Koi keepers are finding that many anti-biotics treatments are simply no longer working. Have we gone too far with the indiscriminate use of anti-biotics?

This year we have noticed many koi imported from Japan and Israel have ulcers on them. Outbreaks of ulcers have occurred in koi collections around the country. Collections have been devastated in some extreme cases. Some Japanese breeders are reluctant to sell koi until the problem is resolved. It is common knowledge that breeders and dealers overseas, and in South Africa, are feeding koi regularly on feed laced with antibiotics or adding various antibiotics directly to the water. In hatcheries and dealership situations, the very high stocking densities and handling stress predispose koi to infection. The breeder / dealer often has to undertake a program of medication to keep infections in check.

The continuous unchecked use of antibiotics must be damaging the natural immune system of our koi. Anti-biotics are indiscriminate in their destruction of bacteria. Many bacteria found on living organisms are critical for the survival of that organism - humans included. However, after continuous anti-biotic treatments some fish have virtually no natural immune system to fight infections that occasionally occur because they have been medicated to the point of no return.

In the event of the external mucous lining of the fish been damaged and the flesh exposed to naturally occurring bacteria and viruses an ulcer can occur. The sore becomes apparent as the infection spreads in the immediate area. The immune system kicks in and the damaged issue is repaired as the fish returns to normality. The repair of tissue is dependant on the health of the individual fish, the temperature, the nutrition and the quality of the environment.

Over the years, many bacterial pathogens (disease producers) in fish have been identified. Of these, the one of the most important in freshwater fish is a bacterium named Aeromonas. Both as a primary infection in wounds or a secondary problem as the result of stresses, such as rapid temperature changes, handling, poor water quality or parasites, Aeromonas has emerged as one of the most prevalent bacterial pathogens.

There are several types (species) of Aeromonas. In a recent study funded by the Western World Pet Supplies Association, the laboratory identified three different species of Aeromonas present in kidney and wound samples from fish imported from Singapore fish farms. Each species was able to cause infection, and often two species were isolated from the same sample.

Of the species of Aeromonas, the one most familiar to the hobbyist is Aeromonas hyrdophila. There are many names for the infection produced by this bacterium, ranging from the scientific version, known as haemorrhagic septicaemia, to the layman's version, called redsore (ulcers) and dropsy.

These names describe the main features of an infection that can take at least three physical forms. One of the most obvious is the external haemorrhagic (bloody) ulcer. These open wounds appear as localised ulcers on the body of the fish, often with areas of dead tissue and sloughing scales. Haemorrhages also may appear at the base of the fins.

Some researchers postulate that Gyrodactylus (body flukes) may act as carriers for the bacteria. The bacteria enters the wounds in the skin and gills made by the flukes. Other types of abrasions or tissue damage may also play a role in establishing infection.

Another easily identifiable form of bacterial disease is dropsy. This condition, in which the abdomen fills with fluid and appears swollen, is due to an internal bacterial infection in the kidney, liver or intestinal tract. The resulting disruption of normal circulation of blood and other fluids causes a backup in the system. The fluids accumulate in the intestine and abdominal cavity, resulting in the distension of the abdomen. In severe cases, the scales may stand out from the body, displaying the so called pine-cone disease. Sometimes the eyes may appear to bulge.

A further variation of Aeromonas bacterial infection does not produce any noticeable external ulcers. However, the most notable feature is a behavioural change in which the infected fish generally become lethargic. Some fish may lose colour or appear darker. Blood vessels are apparent in the white areas of the skin. The fish do not feed, frequently seem off balance and may sink to the bottom laying on their sides. Some fish hang lethargically at the surface. The course of the disease is often rapid as the bacteria produce potent toxins that account for the severity of the disease. In some extreme cases by the time the behavioural changes are noticed, the entire population of a pond may succumb in a few days. This has been observed many times after the introduction of new koi to the collection, much to the dismay of the enthusiast. Fortunately, in many cases the natural immune system fights the infection and the fish recovers.

Another bacterial species Aeromonas salmonicida, causes what is sometimes referred to as goldfish ulcer disease or GUD. The classic feature of GUD in koi and goldfish is the development of a large circular, very shallow haemorrhagic ulcer, generally occurring on the sides and belly of the fish. Infected fish are depressed and lethargic, lose their appetite and become darker in colour. The ulcer has a centre of dead tissue that is very susceptible to secondary fungal infection. The outcome of this disease is variable and depends on the immune response of the infected fish. Complete healing of the ulcer can occur but often resulting in an extensive darkly pigmented scar. In other cases, the disease becomes systemic, resulting in the death of the fish.

There are many remedies for ulcers. However, excellent water quality accompanied by water temperatures above 20 °C are important. Warmer pond temperatures increase the fishes metabolism and healing rate. Fresh, high quality nutrition (either pellets and/or live food) to rebuild the body together with an attempt to seal the ulcer to assist the body’s defence mechanisms and protein rebuilding process.

Ulcers in the human mouth are very irritating and take some time to heal. The same principles apply to koi. We treat mouth ulcers every day - the same should apply to the fish. Some ulcers are very prescient. Anti-biotic injections and treatments do not always appear to benefit the infected fish The following suggestion is but one of many the hobbyist can try.

Equipment: (1) A bowl of adequate size. (2) A correct size koi net and a sock net. Both are available from koi dealers. (sock nets = a net which in made of soft material open at both ends.) (3) Medication available at the local chemist - Hydrogen Peroxide (10% or 20% strength) and Fryers Balsam. (4) A second “medical” sock net is most useful and can be made by cutting a small hole in the middle of the material. This sock net is left over the fish which will calm it down and prevent it jumping out of the bowl. (5) two eye droppers.

Treatment: The fish is caught in the main koi net and brought gently o the edge of the pond. Do not lift the koi out of the pond in the round net. Scoop the fish gently into the sock net, hold the one open end closed and lift the koi out of the pond into the bowl. If you are using a second sock net slide it over the koi and position the hole over the area to be treated. Once treatment is completed the fish is lifted in the sock net and returned to the pond. One of the least stressful ways of moving and treating koi.

Hydrogen Peroxide (10% or 20%) is poured onto the wound / ulcer to sterilise it. An eye dropper can be very useful in these circumstances. Immediately after the sterilisation Fryers Balsam is poured onto the ulcer. This will seal the sore. Again an eye dropper is extremely useful. Some hobbyists give anti-biotic injections as well. However, the author is against the indiscriminate use of anti-biotics in aqua-culture. Other hobbyists mix Methylene Blue powder into the Fryers Balsam as an anti-biotic. This method work very well.

The treatment should be undertaken every two days if possible. Once the ulcer appears to be sealing the peroxide can be stopped. The other added advantage of this treatment is the two substances are freely and cheaply available at the local chemist.

Dealers and breeds do not have the time to treat individual fish as they work with hundreds if not thousands of fish each day. But the hobbyist does have the time. Careful handling, some sound remedies, common sense, continuous attention and a little T.L.C. (tender loving care) can work wonders in the treatment of ulcers.

Chris Neaves

Last Updated on Friday, 31 October 2008 12:09