koi quarantine

How to quarantine your pond fish is a common question koi keepers ask.

For 40 days and nights it rained upon the earth clearing evil from the face of the earth
Moses spent 40 days and nights on Mount Sinai receiving God
Israelites wandered the wilderness for 40 years
Jesus spent 40 days in the wilderness
The Egyptian practice of mummification took 40 days to complete
The cycle of 40 is a theme that occurs in the Bible, Torah, and Quran and crosses numerous cultures and ideologies.

All of these incidents resulted in some type of purification. All of these incidents were quarantine.

40, cuarenta, quarante, quaranta
Quarantena means a forty day period in Italian.
Historically many port cities kept ships and people out of their cities for a period of 40 days, they quarantined, to be sure that disease and plague would not be entering their cities.
Quarantine by modern definition is: a period of isolation imposed upon ships, persons, animals, or plants upon arrival for 40 days, when suspected of carrying infectious or contagious disease.

Any good fish professional worth their fins should always recommend that all fish be quarantined before being introduced to a new environment or fish population. Whether quarantine can be practiced or not is another issue. The process of quarantining fish is generally agreed upon by most professionals. The length of time in quarantine, however; is still debated among fish professionals and veterinarians. The objective of quarantine is to assure the health of the fish by allowing enough time in isolation for any health issues to develop in the fish before entering into the general population.
The quarantine process for fish is just that, isolation. The isolation usually taking place in what is referred to as a hospital or quarantine tank (or pond), before introduction to the general fish population. During quarantine the fish should be observed very closely to assure that: there are no signs of stress in the fish. There are no exterior signs of parasitic, bacterial, or fungal infection. No signs of damage to the body of the fish. Also, that the behavior of the fish is appropriate for the species being observed. The parameters of temperature, pH, oxygen levels, and overall water quality should be as stable as possible during this time. During quarantine the fish should be fed regularly with medicated and non-medicated foods. If other medications are necessary they should be administered at this time. Small frequent water changes should be performed. At the end of the quarantine length that you feel comfortable with; the fish should be acclimated to its permanent home and again be observed closely for at least the first few days to make sure the fish adjusts well to its new home.
The length of time is debatable and somewhat at the discretion of the fish owner. Anyone would agree that quarantine should take place for at least 15 days, other professionals and veterinarians have said that quarantine should take place for a period of 6 months or more. So, as can be seen this is a great difference of opinion. My opinion is that 15 days is too short, especially knowing that the common ich parasite can be infecting a fish and not show any signs for up to 17 days. Other health issues can develop at a slower rate as well. I also think 6+ months, for most people, is too long unless you are a collector with some expensive specimens. I do think a very reasonable quarantine period is 4-6 weeks. A 4-6 week quarantine will allow most problems (parasites, bacteria, fungus) to reveal themselves and present the opportunity for treatment if need be, and this period also falls within the classic definition of “quarantena” and if it was good enough for God, it is good enough for me.
The practice of quarantine, a good practice it is, still does not guarantee that your fish are free of disease. It is pretty well known in the industry that KHV, koi herpes virus, can lay dormant for years. KHV can also be carried by fish that never succumb to the disease themselves; however, they can do a fine job of passing the disease along to all your other fish. Quarantine does not offer any guarantees, which is why my personal feeling is that 4-6 weeks is a “safe” quarantine period.
The practice of quarantine can be a little sketchy as well within the fish keeping industry. Unfortunately, some exporters, wholesalers, retailers, and dealers may claim to have quarantined fish but you should really check your sources. Many retail sellers of fish simply do not have quarantine facilities (Walmart and Petsmart are NOT quarantining their stock). Many hobbyist fish keepers cannot have quarantine facilities, myself included. Quarantine takes time and money, and sometimes fish keepers and fish sellers simply take the risk. I personally do not have quarantine facilities and have put fish directly into my pond with a prayer, and to date have been lucky (yes, lucky) to not have any disasters. I cannot recommend not quarantining your fish even though I have done that, I am just being honest about how I handle my personal fish for my own pond. But working in the industry, it is my practice to advise fish keepers to ALWAYS quarantine your fish if you have the ability to do so. For those that have suffered the negative effects of not quarantining, like fish loss, if they could go back in time they would absolutely have done it. So it would be a hard lesson learned.
It has been a few years since I have added fish to my pond and I repeat that I was purely LUCKY that I had no issues when I skipped quarantine for my new fish, and I also happened to know exactly from who and where the fish had come from because it was from a pond that I have dealt with for many years, so I knew I was taking a calculated risk. So, in good practice I do recommend to EVERYONE who reads this; quarantine your fish if you can, or ask if your fish dealer has quarantine that they offer as a service. There are many koi dealers who will hold fish for their buyers, it will have a premium attached to a service like that, but it could be well worth it!
All copyrights to this material belong to Mike Gannon.


Rebecca Cooper

Great post. Very well written. I quarantined 6 six inch shubunkin last year for two weeks. They had had enough at that point and so had I. It is difficult. Prayer is much easier.


Thanks for the comment Rebecca. I guess everything goes better with a bit of prayer!


Leave a Reply

Your email address will not be published. Required fields are marked *