Quarantine Koi

Many beautiful collections of koi are lost every year because pond keepers do not quarantine their new koi fish.

One of the major causes of koi deaths and sickness this year and every year is the failure of pond keepers to quarantine their new koi. Collections of koi that were family pets for years, are all gone, because new koi with health problems were introduced to their pond.

Let’s make sure this catastrophe does not happen to you. But first, before we talk about koi quarantine and if you have a nice clean pond full of happy, healthy koi that you have become attached to over the years. Ask yourself this question: “Am I willing to risk the health of my koi and pond for a new koi fish?”

Now there are times when adding new koi to your koi pond is necessary and that’s when knowing how to properly quarantine new koi is priceless because it greatly reduces the risk of introducing koi parasites and bacterial infections to your koi pond.

Koi Quarantine Tank Type

One of the best tanks you can buy to quarantine your new koi are fiberglass tanks. They are ideal for livestock and are very strong but light. Plus, they can come with a bottom drain that you can attach a valve to that makes them very easy to clean and do water changes.

Another good feature is they are deep which will help keep your koi from trying to jump out.

Quarantine Koi Tank Size

You do not want to crowd your koi when they are in quarantine.

One of the best quarantine tank sizes are 150 US gallons and 300 US gallons. With proper care, lots of water changes and testing the water every day in your koi quarantine tank for ammonia, nitrites and pH, a 150 US gallon tank should handle up to four or five 10 inch koi.

Location of your Koi Quarantine Tank

The location of your quarantine tank should be near an electrical outlet, a tap water source and not in direct sunlight all day.

Koi Quarantine Tank Covers

All quarantine tanks must be covered to protect your koi from jumping out and to protect your koi from predators. However, your koi do need sunlight and open air.

Do not use glass or clear plastic because it will increase the water temperature. A strong, heavy plastic mesh with a strong frame should work as long as it is predator proof.

Quarantine Koi Tank Aeration

Lots of aeration with tiny bubbles coming from the bottom of the quarantine koi tank is very important.



You can have the very best of everything for your quarantine tank, however, if you do not keep the water in 100% condition, free from waste, ammonia, nitrites, low nitrates and low pH your fish will suffer. You must place an “aged” filter on your quarantine tank as soon as you introduce your new koi.

An “aged” filter is a filter that has the “good bacteria” already started in the filter. If your filter is not “aged” the water in your quarantine tank will quickly become toxic with ammonia. Many times pond keepers think their koi are sick from a parasite or bacterial problem only to find poor water quality in their quarantine tank is really the problem.