Preparing New Koi for Sale

Published on March 25, 2009


Laguna Koi Ponds

How to Get started and What to do

Are you doing everything you can do to deliver healthy koi to your customers? Since koi can carry a wide number of diseases and parasites, it is vital that you establish a regular procedure to isolate, acclimate, and treat all new koi before putting them out for sale. There are just too many potential problems that can be caused by not quarantining, not only for you as a dealer, but also the risk of what you could pass on to your customers’ ponds.

This may sound daunting if it is new to you, so we have asked Ben Plonski, owner of Laguna Koi Ponds in Laguna Beach California to tell us how he prepares his new koi for sale.

Creating and maintaining a reliable “new koi” health plan will pay great dividends in building your shop’s reputation, which is very important to the long-term success of your business. Customers appreciate dealers who are serious about quarantining. They want to know what you do and how you do it.

The goal of quarantine is to build the strength of the fish and to prevent the spread of disease; for example, KHV (koi herpes virus). You will also occasionally have parasites and other little bacterial things on them that you will need to treat for. It is the stabilizing process and building/strengthening the koi’s immune systems that is the primary goal of quarantining your new koi. This is what will ultimately save the fish; stronger fish have a better chance to respond immunologically to the diseases they will inevitably face as they move into new environments. What you are doing is not only making sure you are not introducing new diseases or parasites into your shop and your customers’ ponds. You are also strengthening them to face the new bacteria and parasites they will face for the first time when they get into your customers’ ponds.

Getting Started

The first step is to establish a separate area to quarantine all new koi. Get started by setting up separate holding tanks – you can never have enough tanks as dealer. I estimate that you need as many tanks in the back to quarantine, as you have out front to hold koi for sale.

All In – All Out

All koi from new shipments need to be kept together and never mixed with any prior shipments of koi. Even though the customer will eventually mix his fish, you the dealer need to keep them separate, if not indefinitely, for as long as possible.

New fish arrive and go into the quarantine tanks, based on their size and quantity. If you over crowd you tanks, you will not have stable conditions, so quarantine tanks need to be big. When you set-up your quarantine area, be sure that you can make water changes easily. You will need to make small, frequent water changes easily.

When new fish comes in, they are stressed out and very weak. Put them in a quarantine tank that has 0.5 percent salt. Some may feel this is too high a percentage salt. This is what my Japanese breeders recommend and we have been using this level (without plants) for almost 20 years with very good results. The koi should only stay in this level of salt for up to one month. During your quarantine period you should be slowly reducing the level with small water changes. Be sure the new koi stay in this level for at least one week. If the koi are weak or cold you may want to keep the level of salt at 0.5% for a full month.

The pH should be closely matched to the water that is in the bag that you are receiving the fish in. If you don’t know the pH, adjust the pH in the quarantine tank to 7.0. Fish in bags normally have a low pH: starting as low as 5.0. A neutral 7.0 pH will help reduce the shock to the fish as you take them out of the bags.

Temperature Control is Vital to Success

Most breeders/koi farms now medicate for parasites prior to shipping so the fish should be pretty clean when you receive them, but they are going to be stressed. Controlling the water temperature is an important (and maybe the quickest) way to help the fish recover from the stress of shipping.

You must have the ability to heat the water, to control and manipulate the temperature of the quarantine tank. The heat will help you build up the strength of your fish. The temperature of the quarantine tank should be the same as where they came from, so you need to ask your source what the local water temperature is when you place your order. Thus, if the koi farm you bought them from has a water temperature of 80°, then the water in your quarantine tank you receive them in should be at 80°, even if the temperature has dropped during shipment. The fish should be received at the same temperature that it was accustomed to prior to shipment. Floating the bags will bring the temperature up gradually before releasing them into the quarantine tank. Once the fish have gone through quarantine, which could be up to 4 weeks, you can slowly bring the fish’s temperature down to ambient temperature. No more than 2 degrees per day.

If the fish are coming from a lower temperature, receive them at that matching temperature, but then slowly bring them up to a temperature range that is better for the fish, around 75° – at no more than 5 degrees per day.

For the first couple of days, with your quarantine tanks at 0.5% salt, you should just let the fish rest and begin to regain strength. Cover the tanks with something like shade cloth to help reduce stress and prevent jumping. Do not feed them for the first two to three days. Then slowly introduce small amounts of small size food, to allow the fish’s system to start working again. The fish may act like they are starving and begging for food, but resist the temptation to over feed them for the first week. Go slowly to wean them back onto food. Be sure you are steadily increasing the amount of food. Feeding is also part of the strengthening process.

You need to keep the water quality high. You probably will want to test for ammonia and nitrites ever two to three days. Make sure you have good aeration. You normally will not have to do anything to your biological filtration, but be sure to clean your pre-filter.

The first week is all about strengthening the fish and getting them back onto food. After about five to seven days, then you can start medicating with things like Malachite Green or Proform C together with Fluke tabs or Praziquantel. Two to three days later we give them a second dose of Malachite Green. Then after another three to four days we will treat them again with Malachite Green and Fluke tabs. You can use over the counter malachite green or make your own; either way your dosage should produce between 0.05ppm to 0.10 ppm. Actually malachite green is pretty safe and koi seem to be able to tolerate even higher doses. However, it is best to be scientific and use known quantities. We use “Fluke Tabs” for resistant flukes, fish lice and anchor worm but we wait one week between each treatment. This combination is safe together with salt at 0.5%. The Pro-Form C is a very good medicine but may be too harsh to use together with salt, so it would be best to reduce your salt level to 0.25% or less before using Proform C. Praziquantel is also good for flukes and crustaceans and the choice is up to you. The Salt however, is very therapeutic and should be maintained for at least the first week. Do not try to be in a rush, you will just damage your koi.

With the salt level at 0.5 and the above medication treatment you will cover most of the common fish ailments: Flukes, Fungus, Chilodinella, Fish Lice, Anchor Worm and Ich. This will not necessarily eradicate Costia and Trichodina. After the last dose of Malachite Green and Fluke tabs you can give a low dose treatment of Potassium Permanganate to help with Costia and Trichodina. Your salt level should be reduced to lower than 0.25% before using Potassium Permanganate. One dose at 2 to 3 ppm will help with Trichodina. Costia, however, might take multiple doses over a few days. Be careful with Potassium Permanganate. Too high a dose or too many multiple doses will dry out the mucous. Remember, you cannot sterilize a koi without killing it. These medicines do not completely eradicate parasites. Parasites are always part of the koi’s environment. The two bugs, costia and trichodina, are what I consider “commensal;” meaning they are always present on the koi in low levels. As long as the koi maintains his strength and water quality is excellent, you should not have big problems with low levels of these bugs. However, it does not take much for these bugs to explode under improper conditions. Diligence continuously is key.

So, the first week you normally are building the fish’s strength and getting them back on food, unless they are really sick. The second week you are medicating. The above medication treatment is what we have found works, but there are many medications out there that will work and you may want to try different things and see what works for you.

At the end of the second week, you should do some scrapings and examine them under your microscope. You must have a microscope to really know what is going on with your koi. Do at least three or four fish, to make sure there is no longer any thing going on with them. Try to look at the fish and pick one that looks weak and/or stands off from the crowd. If you don’t find anything they may be ready for sell. Editor’s Note: If you have never done scrapings of koi, it is a good idea to attend a koi health lab and get hands on training. Labs are held across the country by a number of vets, dealers, associations and universities. Watch our upcoming events area at

This regime addresses pretty much everything except KHV.

Dealing with the KHV Threat

Can you trust your source of koi? Should you trust your source? At this point you should take it to the next level, by testing for KHV. You will need to draw blood samples, preferable with the help of a local vet, and send them to the lab to be tested. Once you send in the samples it will take at least another week to get the results back from the lab. Each sample does cost to be tested, but try to do as many as you can.

U.C. Davis does have a new test for KHV. It is a more sensitive (and validated) test for KHV antibodies. Some believe results from a “sampling” may not be enough; that you need to test almost every fish. (Editors note: On is an article further explaining sampling procedures.)

This is also why you need to keep the quarantine water temperature around 75°F. If you have had them in quarantine for three weeks at the 70°F to 75°F temperature (or two weeks at 75°F to 80°F), the fish should break out with KHV if they have it. If they have not broken out and you combine that with a negative test result, you can feel pretty confident about the whole batch. You also need to be able to trust your source. There still could be a carrier, which is why the antibody testing (above) is recommended.

Here you are now at three weeks. Your customers want to buy your fish. You are now either loosing money or you are building your reputation. It is all in how you look at it – your perspective. Which is most important to you?

Getting ready to sell the fish, you will now (in most cases) have to start lowering the temperature of the quarantine tanks. What is the average temperature of your customer’s ponds? What is the ambient temperature in your region? That is the temperature you want to achieve before that fish leaves your shop. This may take as much as another week. You can only lower the temperature a few degrees a day.

Quarantine protocols can take as much as a month, before you are ready to sell your fish. A fair quarantine can take three weeks and a minimal quarantine should take two weeks. Part of this is also dependent on the temperature of the water in your area. If this is during the summer, when water temperatures are high you don’t have to drop the water temperature and thus it doesn’t take as long.

When you have your koi on display for sale they continue to stabilize. The koi is re-gaining its strength from the stresses of being shipped and quarantined. As the koi gains strength it will become better able to adapt to its new environment (another set of circumstances), i.e. your customer’s pond and mixing in with other fish in that pond. So really the whole time you have a fish in your shop it is in quarantine.

Remember you still don’t want to mix your older fish in your establishment, with your newer fish. Keep them separate, in separate tanks even when they are for sale.

If you have had some fish for two or three months and the weather is warm, you could then start to mix some of your older fish together to make room, since you have had them for a while and they have shown that they are stable. Everything really comes down to temperature. (That is the main secret.) If they are in subdued immunological water temperature, say less then 65°F, then do not mix fish. If you do you will increase your risk for trouble.

If you do get to a point where you combine older fish, bring the salt level in the water back up to 0.5% salt. Only leave them in that salt for to three or four weeks.

The Hardware You Will Need

Your isolation tanks must be a minimum of 250 gallons and up to 1,000 gallons in size. The 6´ and 8´round show tanks can also work and are more affordable than some other options. Be sure to cover the tanks, so the fish won’t jump out.

You should have two sources of aeration – one is an air pump for the bubbles, with a diffuser – the second is the splashing water coming back from your bio-filtration. If one source should happen to stop working you will still have aeration from the second source.

The filter should be as large as possible to handle the incoming fish load. This is one area that is often built too small. It is important to have a large amount of filtration. We shoot for filtration that is 10% the volume of the quarantine tank. For example, a 1,000 gallon quarantine tank would have a minimum of a 100 gallon filter. Two 55 gallon barrel filters with Matala filter media is what I use on many of my tanks, but there are many filter systems that will work, as long as they are large enough. We use the Matala BioSteps filter with 18 watt UV on some of our smaller quarantine tanks. We also use 40 watt UV on some of our larger systems to keep water clear. A big UV on a small quarantine pond will give the added benefit of reducing the bacterial count in the water. Obviously with any filtration system you must also maintain the filtration system properly to provide a stable environment for the koi.

Good flow through the filter is the other important variable. We have found that two tank turnovers per hour is best.

While you are at it, don’t forget to have a separate set of nets and tubs to use in your quarantine facility. Sanitize the nets and tubs regularly with a solution of chlorine which is what we use. There are other sanitizers but chlorine has worked for us. We have a tank set up which we can dip all our tubs or nets into. Make sure all your employees understand the rules, and wash their hands whenever they leave the quarantine area.

Remember, you are protecting your investment in not just the rest of the koi in your facility, but the koi in your customers’ ponds, and ultimately, your reputation as a professional koi dealer. Employing a good koi health regimen will give you the pride and confidence that you are selling the healthiest koi possible. It is definitely worth the effort.

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