Quarantine and Acclimatisation

Why quarantine new Koi?

Koi are intensively bred and reared for a world market and this system predisposes a percentage of Koi to health risks. The actual volume of Koi that has to be stocked in outlets to offer variety to the public naturally increases exposure to disease. In addition, the advent of Koi Herpesvirus and other serious diseases has made quarantine more important than ever. Sadly, those hobbyists who have experienced serious disease see Koi-keeping from a more cautious perspective. However, it is still a very rewarding hobby that can easily survive any risk posed by disease such as Koi Herpesvirus. All it takes is an understanding of what acclimatisation is and what quarantine can achieve when it is seen as part of the hobby of Koi-keeping.

Freedom to choose

Every PKDA Koi dealer operates to a Code of Practice and many are certified biosecure. However, not all dealers are in a position to join a trade association and care is required when choosing an outlet .Whilst Koi are much safer if they have been through dealer quarantine there is no standard regime in place outside the PKDA. In addition, Koi can change ownership without a dealer being involved which poses disease risks. Reliance on health certification offers limited protection from disease as there is no standard approach to their issue and many are meaningless documents. Koi must have a higher degree of safety if they have a further period of home quarantine irrespective of where they are purchased. This is far more important when Koi have been obtained from a source where no quarantine has taken place or when the history of Koi is unknown. Koi keepers should understand all the facts but must be free to decide where to buy.

If the dealer has already quarantined why repeat the process?

The purpose of trade premises is to sell Koi, therefore it is unavoidable that they create a greater potential for health problems due to the numbers of fish stocked and the need to bring in new Koi to keep variety on display. This fact applies to all dealers no matter how high their standards. Naturally, risks are reduced when buying wisely from a good dealer who fully quarantines. However, it reduces risk further for the last phase of quarantine to take place in home facilities irrespective of where you buy.

Acclimatisation and quarantine

Quarantine is a period of isolation to prevent disease introduced by new Koi spreading to existing healthy fish. It should not be confused with acclimatisation, the complex multilayered process by which Koi adapt to their new environment. Hormones are released into the bloodstream in response to stress and it is the level and passage of these hormones that influence how Koi adapt to all the changes to which they are subjected. Koi do not arrive with a medical history card tied to a fin revealing what stage of adaptation has been interrupted yet again by the latest move. Some fish are so stressed they fail to adjust and succumb to environmental factors or infect others with latent disease. Koi are uprooted many times in their lives before they find a permanent home and it is only then that they can ever fully acclimatise. It makes sense to ensure that the new Koi are completely healthy before they meet a pond full of established pet Koi.

A two-stage process

Partial acclimatisation is the floatation of new Koi in the transport bag until the parameters exactly mirror those of the quarantine tank before the Koi are released. Temperature and p.H are most important and if there is a variation this can be gradually adjusted by introducing a little tank water into the transit bag and allowing a few minutes for the fish to make the changes necessary internally. Transportation water should not be poured into the tank. The fish should be allowed to settle, unfed or disturbed for several hours. Full acclimatisation is complex and the timescale for this to be completed will vary fish to fish and can depend on the environment the fish is living in as well as the capacity of the fish to adjust to it.

How long shall I quarantine?

One month is the minimum period that would be effective and anything less is impractical. During that time, a parasitic problem, or any abnormality in behaviour or appearance is more likely to become evident. Bacterial infection or latent disease is less likely to materialise without a trigger factor. A three-month period is a more acceptable period but it is important that a natural rise in water temperature occurs or the tank is heated, as without any change of temperature disease may not be revealed at all. Some hobbyists favour a whole year of isolation as they hold the view that it is not possible to know what any fish is carrying, which is a valid perspective but the length of quarantine is personal choice.

I used to quarantine

Hobbyists occasionally lose fish in quarantine and blame the process rather than the facts. If suffering from stress new Koi are just as likely to die in the pond had they not been isolated in a quarantine tank. The actual quarantine process cannot kill healthy Koi. In many cases, the quarantine tank is totally inadequate for the size and numbers of Koi it has to house. It is this that adds to the stress the Koi experience, as they need as much water per fish as possible depending on their size. Quarantining can be a burden but occasionally it saves Koi and prevents heartache, although Koi-keepers may not always be aware of how much the period of quarantine has actually achieved.

I use a potassium permanganate dip instead of quarantine

Dips cannot take the place of quarantine and they are stressful. Potassium permanganate as a dip removes the mucus layer at a time when the fish are about to be bombarded with organisms in the pond and this layer is part of the immune system and rich in protective substances. Dipping makes the new Koi more vulnerable to the harmful organisms in the pond that the existing Koi are more able to cope with, as their mucus layer is intact. No dip can eradicate every parasite and its life cycle, and dips can never prevent disease.

Medications in case of parasites during quarantine?

Test the water continually during quarantine; nitrite causes flicking and flashing and this is commonly mistaken for parasites. It is better to avoid chemicals as most reduce the biology in the filter and being a quarantine tank, this may not be mature. Observe the new Koi closely and make sure they are eating, and swimming normally. Check for excess mucus, abnormal behaviour, or constant flicking but do not medicate if the fish remain healthy. If you have a microscope, view mucus smears taken from a representative sample of Koi to see if there is a genuine parasite problem. All Koi carry some parasites; a few do not constitute a problem. Whitespot is common in Koi that have been moved due to water temperature changes and that will need treatment. Check with the dealer if you are unsure how to deal with a specific parasite.   

Do I need to build a quarantine tank while building my first Koi pond?

The quarantine facility can be built at any time as it should be separate from the pond and not share the same equipment. The initial batch of Koi purchased has to go into the pond to mature the filter system. Stocking slowly over several weeks ensures the filter biology grows gradually to cope with each additional fish, otherwise the Koi are subjected to ammonia, and nitrite toxicity as the nitrogen cycle is established. During this phase, water testing is paramount to ensure ammonia and nitrite levels are controlled as underestimating this danger is the prime problem in all new ponds.

These first Koi are naturally exposed to a higher risk of health problems, not just from the immaturity of the filter but by sharing one another’s pathogens. Losses are common in new ponds and there is an increased risk of parasites and bacterial infections when the conditions are unstable. Later when the teething problems are resolved, this first batch of Koi will have adapted to life in the pond and any health issues dealt with. From this point on the established Koi are at risk when new Koi are added from parasites, disease and overstocking and the quarantine tank comes into use. When the pond is fully stocked, the quarantine tank can be used for fry after spawning or if a fish has an injury.

When Koi become unwell soon after purchase

The main disease risk for new Koi is environmental which means the water conditions are not appropriate. Low dissolved oxygen for example can be a factor in losses that goes undetected. When the conditions are good and losses occur after purchase it is likely the Koi are suffering from stress and its various consequences. No dealer knowingly sells unhealthy fish nor can he guarantee that the stress of the trip home and the new conditions the fish is living in will not have some bearing on how the Koi acclimatise and survive in the long term.

Dealers have to take on trust that Koi-keepers know how to care for the Koi. If they are new to Koi keeping this fact must be made clear to the dealer, as legislation requires a dealer to provide basic information to new hobbyists.

The rules for the sale of an object are simple but when it comes to fish there has to be shared responsibility by the dealer and the hobbyist because of the unique association between Koi and their environment.

After quarantine

On the day, the Koi leave quarantine it is vital the pond parameters mirror those of the quarantine tank. The tank can be heated or cooled accordingly in advance. The Koi should be floated in a bowl of tank water and pond water slowly introduced so that the fish gradually rather than suddenly adapts to water chemistry and temperature changes. This final move is in the hobbyist’s control and can be so well managed that the move is smooth and as stress free for the Koi as possible. Within minutes in the new pond, the swim bladder will be working like the sonar on a ship sounding out the depth and width of the pond. This is vital information that the brain needs as the new Koi adapt to the pond they will call home.