Pond treatment issues When a pond treatment product fails to control a certain parasite, Koi keepers naturally question the content of the product.  However, in so many situations, there is an underlying reason for the ineffectiveness of the product that may not be obvious.  The wise thing is not to rush to use a new brand or different type of product as, in so many cases, this only makes the problem worse, risks further treatment failure, and over exposes Koi and other pond fish to chemicals. It makes sense to consider possibilities before complaining to the product manufacturer. The pond water temperature being too low is a common problem at certain times of year and not knowing the exact volume of water in the pond and filter leads to under or over dosing products. This can fail to cure parasites and trigger a series of pond treatments in attempts to rid the fish of the infection.  Too many treatments can be harmful in the long term and over dosing with any chemical puts the Koi at risk and, if they survive, they can become more vulnerable to disease. Keeping the UV on during pond treatment weakens products and overlooking zeolite in use in the pond is yet another factor.  Zeolite works on the ionic exchange principle and treatment products will be removed. Research has been carried out on certain anti parasite remedies to see how long they are effective in the treatment period and how fast organisms are eliminated. One observation is that pH and KH fluctuations can impact the success and safety of pond treatments. Therefore, ensuring all pond parameters are stable in advance is yet another way of preventing treatment failure. Other causes Whilst these I have mentioned are common factors in the failure to eliminate parasites there are other products used regularly in ponds that are not regarded chemically in the same way as fish treatments. Tap water conditioning products, blanket weed treatments, and some products that improve pond conditions have an important role in keeping pond biology and fish healthy.  They vary in how they interact with anti parasite treatments and, in many cases, could neutralise the action of treatment products. Most conflicts have been found when pond water is treated to remove chlorine and chloramine and some anti parasite products then failed to work. Ringing the manufacturer of any product is recommended although, due to the variables involved, they are unlikely to know why their specific product failed.  No two ponds are identical in respect of water chemistry and, when the numerous products to remove impurities in tap water are factored in, the only guidance possible is not to use another product for seven days before or after using an anti parasite product. Gyrodactylus or skin fluke Skin fluke is not a genuine fish parasite yet it concerns Koi keepers more than other organisms. A true parasite lives off the fish directly and needs to obtain blood whereas skin fluke eat the nutrients they find in the mucus layer. When viewing mucus smears taken from several fish, finding a few skin fluke in mucus is normal and does not need treating.  However, they do become a problem when their numbers increase to a level that irritates the fish and they can sustain a skin abrasion in trying to relieve it.  There are numerous species of flukes in nature and, in recent years, the movement of Koi around the world has introduced species that are new to UK ponds.  These species are more difficult to control and they resist the chemicals used for the more common skin flukes. Fluke Solve Plus developed by Fish Treatments Ltd. is sold by Vet Ark Ltd. and is the first product on the market to treat the new fluke strains. When Koi have a thick mucus layer, the question is often asked should a product be used to remove it before treating for skin flukes. This is not ideal for Koi as it involves using two chemical treatments in quick succession and they are vulnerable without their mucus layer.  Whilst thick mucus appears to trap flukes making them difficult to eradicate, most fluke treatments are able to penetrate the mucus.  It is better not to assess the skin fluke level until a full course of treatment is completed as it will take time to be effective. If fluke are very stubborn, one of the newer species may be the problem. Criticising pond treatment products Parasites are not the only reason to treat a pond and products to lower bacteria can also be affected by substances introduced to the water at around the same time. It is safer to use the product first that targets the more serious health issue. Pond treatment is a misunderstood aspect of fish welfare and recently a Koi keeper told me he advises against the use of Chloramine T as it never works. I explained that his treatment failure could be due to the condition of his pond or the use of other products although I suspected he used a generic form of Chloramine T illegal for fish use.  There are various grades and it should be purchased from a Koi dealer with directions for use. His description of the health of his Koi suggested the disease involved several bacterial strains and was so well advanced that no antibacterial treatment product, including Chloramine T, would be of any benefit to the Koi.  Having proven in my laboratory that Chloramine T lowers harmful strains of bacteria found in ponds, I advise using it when disease is suspected, not when it is too late.  There are no miracle cures in bottles or packets and I hope the Koi keeper sees disease in its true perspective in future and does not judge any product based on their own failure to treat their fish at the appropriate time.