Introduction.

Whether or not to quarantine has always been a controversial topic amongst Koi enthusiasts, but we must ask the question of ourselves "how lucky do I feel ?", because not quarantining any new fish is taking a significant risk with the rest of your Koi. There is always a risk that you will introduce a potentially dangerous infection into your pond with devastating, heart breaking and not to mention costly, consequences.

In an ideal world we wouldn’t need to quarantine, but how confident are you that the source from which you acquired your new Koi has quarantined it ? All reputable dealers will do this, as they rely upon maintaining their good name and generating repeat business, but it’s ultimately up to the individual hobbyist to decide. For the inexperienced, I believe that this is a very difficult judgement to make. In the final analysis I believe that it simply boils down to risk assessment, and deciding what level of risk you as a Koi keeper are prepared to take.

Another reason for quarantining would be for post Koi show observation, particularly if your fish have been in a Japanese style show, mixed with other hobbyist’s fish. An efficient quarantine system will also act as a good "growing-on" system for smaller Koi, when not being used as a quarantine system.

The main reason for quarantining is to protect the rest of your Koi from becoming infected with what ever parasites, bacterial or viral infections the new fish has carried with it. Over the years I have lost count of the number of major Koi health problems I have been called upon to help out with, and more often than not the problem was traced to the fact that new, infected fish have been introduced directly to the pond, sometimes resulting in major losses. It seems that nearly every year now, rumours of major health problems circulate on the Koi "grape vine" with significant losses being reported, and advice being given to be very cautious when purchasing new fish.
So, what is the Koi hobbyist to do for the best ?

My advice is that if you have, or can build, an effective and efficient quarantine facility, then I would quarantine every time, but why quarantine if you have bought your fish from a highly reputable Koi dealer who guarantees their fish as "Fully Quarantined" ? Well, again experience over the years has shown me, and other hobbyists in the Section, that the stress associated with transporting the fish from dealer to new pond can give rise to suppression of the Koi’s immune system, laying it open to any advantageous parasite or disease. Even in our Section I know that this has happened, following initial careful microscopic examination of mucous samples and declaring the fish to be "clean", only to find a week or so later that the fish is carrying a very high load of parasites and looking very sick. This also probably explains why the "get it home and give the Koi a quick dip" (e.g. in salt or potassium permanganate), even after microscopic analysis, often just doesn’t do the trick.

Putting newly acquired fish into quarantine has a number of advantages. It allows the hobbyist to carefully observe the Koi for any signs of ill health, and to carry out specific treatments if necessary . It also has the advantage of only treating the fish in the quarantine system, and not the healthy fish and carefully nurtured filtration system of your main pond. It is worth reminding ourselves at this point that any medication is stressful to your Koi, and many of them are deleterious, in some way, to your biological filtration system too, so any unnecessary treatment is to be avoided at all costs.

• They have lost fish during quarantine.
• They don’t have a quarantine facility or don’t have space for one.

Often the reason for losses is poor water quality and environmental conditions, and this topic I will cover later in this article. A quarantine system need not be difficult to build or very costly, especially when compared to the cost of a good Koi, or killing some, or all of your existing collection !

What is required of a good facility?

Maintaining a good environment for the fish in quarantine is an absolute essential. If this cannot be achieved it is far better to place the fish directly into your pond and take your chances.

• The essential elements of a good system are : -
• A suitably sized (insulated) container, which can be covered with a net.
• An efficient and well matured filtration system.
• The ability to remove fish waste from the pool.
• Heavy aeration for pool and filter.
• Temperature control (heating).

A big enough filter to cope with the desired stocking rate is also required, this can be a purpose made commercial unit or a DIY job made from plastic cold water tanks for example (this is what I use). Mechanical and biological filtration elements are required. A common mistake is to set up a filter with media that has not matured, fish are then introduced, and soon the resultant water quality is very poor, and losses occur. An easy way to overcome this is to keep mature, light weight media, specifically for this purpose (e.g. Brushes, Perlag, Flocor, Matting etc.) in the filter system of your main pond. Media such as Flocor and Perlag can be contained in mesh bags to make transfer between systems quick and easy. It is advisable, when setting up a new quarantine system to half fill it with pond water, and then half tap water that has been treated via a commercial purifier/ filter (or a tap water conditioner solution). This will ensure that chlorine levels are very low and will therefore not damage your Koi or your newly set up and fragile filtration system. The turn-over rate through the filter should be once every two hours approximately. Using a UV lamp will also help maintain good environmental conditions by helping to keep parasite and bacteria levels low.

The syphoning/ removal of waste on a regular (at least daily) basis is essential in maintaining good conditions. Daily water changes of at least 10% are recommended. Ideally, top up water should have been treated with a purifier/ conditioner or previously "matured", and be at the same temperature as the pool.

Monitor the usual parameters regularly i.e. Ammonia, Nitrite, pH, Oxygen and temperature.

Heavy aeration is essential in a quarantine system. Even in a modest, heated system I would recommend the use of aeration at the rate of 40 - 80 litres per minute, i.e. a Hi-Blow 40 or 80 (or it’s equivalent). This is a major element in ensuring good oxygen levels as well as good water quality by helping to reduce ammonia levels. It is also important to recognise that the medications used can reduce dissolved oxygen levels. Remember also that at higher temperatures, oxygen levels will be reduced.

In summary, being able to maintain the quality of a relatively small volume of water in such a system, to the highest standards, is absolutely essential to the well being of your Koi.

It is not advisable to quarantine a Koi by itself, as they are not solitary fish, and therefore this can be stressful in itself. Most hobbyists seem to have a tough, "mongrel" fish they use for this purpose !

• Overfeed.
• Over-medicate.
• Forget to observe the Koi.
• Forget to check for the correct operation of your system.
• Disturb or handle the fish without good reason.
• Subject the Koi to large changes of temperature or water quality.

How long do I quarantine for?

An often asked question is "how long do I quarantine for ?" Experience tells us that a period of 4-6 weeks at a temperature of 18 - 22 + degrees C as a general guideline, is usually sufficient to check and treat for parasitic infections, and any virulent bacterial problems. However, a period of up to 8 -10 weeks may be more appropriate in some circumstances. The temperature is critical in relation to the quarantine period, as using a lower temperature could mean that some problems and symptoms may not become apparent until some point in the future when higher water temperatures are encountered by the infected fish. This is why I believe that Koi bought in the Autumn appear to be OK until they experience higher water temperatures in the Spring/ early Summer. This is particularly the case with bacterial problems which lie dormant in the Koi in cooler water, and require higher temperatures to exhibit clinical symptoms. The quarantine system’s temperature should be raised or lowered very gently, no more that one degree C per day. For the first week of quarantine (if no problems are apparent), I would recommend that the Koi is left alone to rest and kept quiet, with ¼ - ½ ounce of salt per gallon. Then, just observe and take mucous samples to check for parasites.

Diagnosis and observation

Accurate diagnosis is essential when deciding whether to treat and therefore what to treat with. As far as parasites are concerned, the only sure way to do this is using a modest microscope with a magnification of 100 - 400X. A microscope, or having access to one (perhaps via your club), is really an essential piece of Koi keeping hardware, and takes all the guess work out of diagnosing microscopic parasite infestations. However, it does take a little practice at first. Check visually for the presence of anchor worms and fish lice which can be seen with the naked eye. Also, pay close attention to the condition of the gills, finnage and the general behaviour and demeanour of the fish. Look closely for damage or discolouration of the gill filaments. It may be necessary to anaesthetise your Koi to inspect or treat it, but do not attempt to anaesthetise a fish which has been medicated. Experience shows that it is very difficult to resuscitate such a Koi. Treat your fish only if it is required, and usually treatment for parasites or minor wounds is all that is required. Seek advice if required, from your local Koi club , Koi Health Liaison Officer, an experienced hobbyist or dealer.

Always assume that Koi in quarantine are potentially infectious to your other Koi. So practice good hygiene by using totally separate nets, bowls and other equipment. Water aerosols can also carry infection from one system to another, so good physical and geographical isolation of your quarantine system from your main pond is advised. Last of all, don’t forget to wash your hands after dealing with fish in quarantine. Wearing disposable latex/ surgical type gloves is also a good idea, if you can obtain them. Even better, get your partner involved, and one of you look after the main pond and the other one looks after the quarantine system ! Once you are convinced the Koi is "clean" it may be then introduced into the main pond. It may be advisable to adjust the temperature of the quarantine system close (plus or minus one degree C) to the temperature of the main pond in order to help facilitate a smooth and stress free transition.

Conclusion

I hope that you have found this article informative and has offered some "food for thought" and perhaps encourage you build yourself a quarantine system, and reduce the risks associated with acquiring new fish, thereby protecting the health of YOUR beloved Koi.