PREVENTION NOT CURE By Dr Paula Reynolds LFH Laboratories In koi there are various forms of bacterial disease that require a different approach to diagnosis, treatment, and prevention. This article focuses on the ulcerative form of bacterial disease currently concerning koi keepers. It’s a fact Fish are not covered by the Veterinary Act of Parliament which means that no veterinary surgeon has an obligation to prescribe antibiotics for fish and, currently, very few do.  Some vets consider prescribing even once could lead to further requests for antibiotics when, in reality, there is ongoing disease in the koi pond. Disease outbreaks can be an indicator that the pond needs new management practices to prevent any reoccurrence.  Many koi keepers with bacterial disease in their koi look for antibiotics on the Internet and such sales can require a prescription to keep within the law. Some illegal sales could place those selling at risk and, occasionally, a product labelled as an antibiotic from another country is not genuine and such scams are increasing. Antibiotics are used indiscriminately all over the world; the UK being no exception. If they were available on demand in every country, all life on our planet would be at risk.  Antibiotics are not wonder drugs; they save lives when used appropriately. Hobbyists who stock antibiotics for even occasional use, without the expertise to use them safely or effectively, could be unknowingly harming their fish and shortening their lives. Koi keepers can no longer rely on obtaining antibiotics and that requires an insight into what is currently happening in many ponds. Keep in mind there are various types of bacterial disease that koi can contract and this article is covering only one form to avoid confusion. Increased levels of disease The number of outbreaks of the ulcerative form of bacterial disease in koi ponds has increased considerably in recent years and antibiotics have not been an option for many koi keepers.  The water fish live in is home to many bacterial species; some are harmless and others such as Aeromonas and Pseudomonas can cause disease. E. coli can trigger health issues in humans and is also found in koi ponds. Aeromonas has various subspecies that are commonly isolated in laboratory cultures taken from koi with skin ulceration.  It is a facultative organism which means it can survive with or without oxygen and thrives in areas where matter collects. At the pond side, it might be assumed that bacteria is the cause of a disease outbreak based on skin changes. However, there are unknown facts such as the bacterial species involved, what stage the disease has reached and how the immune response is coping in each infected fish. The question also arises if any antibiotic will be effective and will the fish receive the correct dose level? It is not only the severity of disease that lowers the potential for fish to survive, antibiotic resistance is also a factor.  Injection technique is also relevant as many koi are damaged and, often, the antibiotic is expelled from the injection site. Caution before chemicals When koi keepers are worried about their koi, they should avoid knee jerk reactions as they commonly make any problem worse. Irrespective of any changes in the behaviour or appearance of the koi and, even if bacterial disease is suspected, test the water parameters before using any chemicals. It may be the wrong product or there could be an alien substance in the pond. Tests kits should be in date and include pH, KH, dissolved oxygen, ammonia, and nitrite. In addition, ensure chlorine, chloramine, or heavy metals have not been introduced in tap water and that any recent rain has not been acidic. If a microscope is available, mucus smears should be taken from several koi to ensure no parasites or free-living organisms are a factor in what is being observed in the koi. Many dealers offer parasite checks for those without a microscope. The investigation should also cover any changes made to the pond including new equipment and products used recently.  If new fish have been introduced, observation can suggest which group are showing signs of the health problem, either the new or the existing koi.  No two ponds are identical as the water chemistry, temperature, stocking level, biology and how the pond is managed all differ and these variations influence how and why disease develops. The early stages I am not repeating myself; I am reminding readers this article is not dealing with all types of bacterial disease only the ulcerative form. Koi rarely refuse food or become lethargic in the very early stages of this form of disease. There can be exceptions because every koi is unique and any fish can have another underlying health issue.  It is more common for fish to be listless and less keen to feed when this form of disease is advanced.  It is also possible for koi with ulceration to behave normally until their immune response fails to support them. As koi succumb to ulceration, in some cases a slight film is seen on a few locations on the body, or there may be pink or red patches, or open skin is observed.  Immediately signs appear, test all parameters as suggested previously as ponds must be safe for chemical treatment and introduce a bactericidal product for example Chloramine T. In addition, treat all skin lesions immediately with Tamodine or another iodine-based fish treatment product to stop the activity on the skin but do not  seal this type of lesion. If the pond filter copes with chemical use after 7 days repeat the treatment and re-treat the skin lesions every 3-4 days.  This is not a cure. It is only when both pond and skin treatments are carried out immediately that the signs are observed that disease might be averted. It is essential to monitor every koi continually for signs and some bacterial strains favour conditions inside the mouth which can remain undetected and are harder to treat. Bactericidal products lower harmful bacteria in pond water and on the skin only during the very early stages of ulcerative bacterial disease and, when used too late, antibiotics will be required.  Do not use potassium permanganate in place of Chloramine T or at any time during this type of disease outbreak. Harmful bacteria from the pond filter Pond filtration systems are, by design, conducive to the replication of bacterial species and therefore will contain both good and bad bacteria. The good or useful bacterial species that make the pond water safe for koi thrive alongside the bad or harmful species that put koi at risk if circulating in the water. Unlike other types of bacterial disease, many outbreaks of the ulcerative form are triggered by pond filter systems and how they are managed.  After any cleaning procedure it is possible for harmful bacteria to be dislodged and carried in the water as it returns to the pond.  However, if dirty water is flushed to waste before it can flow back to the pond, this type of disease outbreak is far less likely.  Many ponds combine different filtration methods and some incorporate a non-return valve to prevent any contamination while cleaning or flushing is underway.  Water temperature plays a role and in summer or in a heated pond. If the filter is the cause of the disease outbreak several koi could have the early signs of infection within a week of a cleaning procedure depending on the pond conditions. Harmful bacteria carried by new koi Whilst pond filtration systems are the most common cause of ulcerative bacterial disease new koi can also introduce it.  In such cases, the spread of infection to the fish already living in the pond will be slower.  Water temperature will influence the development of the disease considerably and, at summer temperatures, it is possible a new koi that has the disease will show signs within a few days of introduction. Soon one or two of the existing koi will also develop the early signs depending on their own unique immunity.  It is important not to assume a new fish is the culprit, no dealer intentionally sells unwell koi.  It is important to remain objective as in some cases disease may have been underway in the pond unobserved when the koi was purchased.  It is easy to dismiss early signs of ulcerative disease as a minor abrasion. Injuries and bacteria Koi rarely injure themselves unless they take a leap out of the water and end up on dry land.  If a fish encounters a sharp object in a pond and is actually injured, it will send out a warning message to the other pond inhabitants to avoid it.  It is when several koi all have red or pink patches, raised scales, or open skin lesions it is likely to be disease not injury.  When only one koi has a skin lesion the question is could this be the first koi with disease, or is it only an abrasion that will heal naturally? Topical treatment with Tamodine or a similar product can be tried several times or isolating the fish might prevent cross infection to the other koi when disease is suspected.  Koi already suffering with ulcers are open to further strains of bacteria invading the skin lesions and causing secondary infection and this complicates recovery. Species of fungi also live in all pond water and, whilst they cannot invade healthy skin, when it is open for any reason, it can be attacked. Fortunately, many products used topically on the skin will help eradicate it. Pond management Every day koi keepers call my laboratory with koi health problems and, in many cases, it can be too late to save their koi by the time they seek  advice. Bacteria are organisms with amazing survival strategies and controlling them is rarely easy and often impossible. Pond management is the prime deterrent against every disease and condition koi can suffer from however, its scope is overlooked. Keeping the pond free of waste matter and hygienic and testing the water parameters are vital aspects of running a healthy pond although a wider approach is needed and where koi are purchased has never mattered more. Dealers have individual methods of preparing their koi for sale and the precautionary measures that can be applied during quarantine are not possible in all trade premises. Koi keepers often regard dealers as responsible for certain health issues in koi after they are sold and living a new pond. Looking at this from different perspectives can be revealing. Dealers treat koi for parasites and those with experience are likely to allow the mucus layer on their koi to fully regenerate after chemical treatment before they are sold.  There will also be dealers who do not wait for the mucus to return, assuming their customers have healthy ponds.  Without their mucus layer intact koi can be vulnerable if exposed to disease or parasites in their new pond. Some hobbyists dip their new koi in a chemical bath deliberately to remove their protective mucus in case they have parasites before being introduced to their new pond.  In this situation it is the hobbyist who has weakened the defences in their new koi should it encounter disease. These examples make clear why the origins of disease are seldom clear. The only way of  ascertaining the origins of  disease is by fish sampling and laboratory investigation. Extending pond management Agents that carry out any pond side service, such pond maintenance, should use a vacuum and other equipment that has been disinfected or there is the risk of cross infection from previous ponds.  Sharing pond equipment such as nets etc. with other koi keepers is a risk no matter how healthy their koi appear. Anyone with access to the pond to check koi for parasites or test the water must use a disinfected net or one on site. Failing to disinfect second hand items such as a pond filter is a common mistake koi keepers make.  It is easy to think preserving the filtration bacteria in the media is a good idea although this overlooks the harmful bacteria it can harbour. Even gifts of koi have been known to introduce disease and few hobbyists quarantine their new fish. Buying unwanted koi that need rehoming is far riskier than purchasing from a genuine koi dealer.  The origins and medical history of such koi are totally unknown and they can be carrying disease whilst appearing healthy. Such fish can end up on sale at koi auctions or be free to a good home.  It is illegal to dispose of unwanted fish in open water and, naturally, some hobbyists will feel some concern. Koi keepers with one pond that is home to valuable prize winning koi or much-loved pet koi cannot take the risk such fish pose.  New koi may have been quarantined by the dealer they were purchased from however, how long and how well this is carried out will vary from one koi outlet to another. A further period of home quarantine is another safeguard against introducing a serious health problem to a koi pond.  All koi keepers should have a tank for quarantine that, when not in use for new koi, can be used as a hospital tank. In the laboratory An antibiogram is a laboratory procedure that identifies the bacterial strains causing disease and the most sensitive and safe antibiotic in its treatment.  Additional information about the outbreak of disease can be available depending on how the laboratory carries out the process.  A broad spectrum antibiotic such as Baytril works only in a few cases as resistance to Baytril is becoming common due to its overuse. An antibiogram avoids experimenting with one antibiotic after another as this puts koi at risk and also adds to antibiotic resistance. As so few vets are now in a position to prescribe antibiotics for koi, LFH laboratories are making changes to our bacterial disease investigations and microbiology services. Research work As a research scientist I have had the opportunity to carry out comparative studies in the use of antibiotics in humans and animals including fish.  This work over several years formulated my opinion that antibiotic use in koi is rarely the most appropriate treatment. Damage can occur, as a result of their incorrect use with implications for their long term health and survival. To prevent the level of bacterial disease I now see in my laboratory, higher standards are needed in the koi keeping hobby and at every level of the koi Industry that supports it. Now antibiotics are not so readily available there will be less reliance on them and a much greater focus on disease prevention. This may seem negative to koi keepers when, in reality, prevention is safer and more successful than any cure and that is extremely positive.