Quarantine Procedures for New Fish

Why a Quarantine Tank?

This is a common feeling:    if you are the parent of young pre-school or elementary school student, you probably cringe every time they walk in the door, wondering what strange disease they brought home today. And there are probably any number of times you wish you could quarantine your child on a daily basis just to stop the spread of the latest bacterial or viral infection from affecting you and the entire family. As much as we would like to, we cannot quarantine our kids but we can quarantine our fish. The process of isolating new or sick fish is directly parallel to avoiding a family outbreak of disease, so the fish owner should always be ready to handle a q-tank process at anytime.

So, why quarantine? Basically there are two reasons:

  1. Isolate new fish so that their health and condition can be properly evaluated, and
  2. Isolate sick or diseased fish to prevent further spread of the problem and provide an easier way to treat the fish.

And with the q-tank process, we want to obtain the following goals:

  1. Reduce the stress of the new fish in its new environment;
  2. Evaluate the overall health and condition of the fish;
  3. Treat the fish as required; and
  4. Prepare the fish for the new pond.

This paper will focus almost solely on the quarantine procedures for new fish although where the processes overlap for sick fish, these will be pointed out. A properly conducted Q-tank process should take at a minimum two weeks, possibly longer depending on the condition of the fish. For a sick and then recovering fish, the sooner you get it back into the pond, the better off that fish will be. For a new fish, he can wait until you are convinced that he is clean and parasite and disease-free.

Before we get too far into the mechanics of setting up and managing a quarantine facility, one basic rule of quarantine law must be established and never forgotten:


If you believe for a second that the dealer or fish provider has done everything they can to identify and treat the fish prior to sale, you are heading for nothing but trouble. So, take the time to properly conduct quarantine procedures every time.

Setting Up a Quarantine Facility

There are many, many tricks to setting up a quarantine facility and how you do it will depend on your resources and needs. So, first let’s start with what we need for a good quarantine tank:

1. The Tank: The general rule is to make this as large as possible. Many fish owners use Rubbermaid feeder troughs, usually 100 gallons at a minimum. These tanks are tough, lightweight, resistant to almost all chemicals, and easy to come by. They can also be plumbed with bulkheads, ports, etc if needed.

2. The Filter and Pump: Filters for quarantine tanks are essential as the fish will be in the tank for extended periods of time. Here is the first of really good tricks: consider running a filter in your pond all season long for the sole purpose of using it as a quarantine filter WHEN (not if) needed. Filters like the Rema API PondCare make a good choice as they are easy to clean, effective, and highly portable. The addition of some bio balls to this filter makes it more effective. Run the filter all season with a small pump so that it will be mature when it comes time to put the q-tank into operation. It does not matter that the filter has been running in your main pond, just do not put it back into the main pond after the q-tank process is over until you have thoroughly cleaned it. Use a GFCI protected circuit ONLY.

3. Other Hardware: You will also need the following:

  • An airstone (unless your pump provides sufficient flow to make a big, aerating splash);
  • A cover for the tank. Fish introduced into a new environment tend to want to go home and will jump out in a hurry. Leaf screening makes a good choice.
  • A hiding place. To help reduce stress, give the fish someplace to hide either using a floating cover (Styrofoam works well) or a plastic flower tub with holes cut in the side work well too.
  • Grow light and timer. If the q-tank is set up indoors, a plant-type grow light with a timer works wonders. The “natural” day/night process will also help reduce stress. Use a GFCI protected circuit ONLY.
  • Heater and insulation. If the q-tank process is to be done in colder temperatures, chances are the q-tank water will need to be warmed. Household insulation wrapped around the tank and a large aquarium heater (300 watts for 100 gallons) work very well to hold the water temps at acceptable temperatures. Use a GFCI protected circuit ONLY.
  • Large plastic bags (strong/clear) and a separate bucket. Use these to help handle fish.
  • Thermometer.
  • Large flat net
  • Microscope, slides and cover slips.
  • Journal to record the progress and procedures.

4. Medications: Every koi owner should have a stocked medicine cabinet for their fish, including the following medications to be used in the q-tank process. They are broken down into mandatory and optional medications. The optional medications are offered for consideration by the fish owner and represent a higher level of medication use. All medications should be used with extreme caution.


  • Salt – You can use iodized or non-iodized salt. Just make sure that you do not use salt with non-caking additives, such as YPS. Salt is used to manage stress, nitrite uptake, and parasite eradication.
  • Amquel or Prime – Use Amquel or Prime to manage both the chlorine/chloramines of city water and ammonia levels.
  • Fluke Tabs – Fluke tabs are the easiest and most practical way of eliminating flukes, especially in a q-tank environment.
  • Dimlin (Anchors Away) – The commercial version of dimlin is called Anchors Away from Aquarium Pharmaceuticals and is used to eliminate anchor worms and lernea.
  • Iodine – For topical treatment of wounds.
  • Baking soda – to manage KH levels.


  • Potassium Permanganate – Probably one of the most effective but dangerous medications used in the koi industry. A powerful oxidizer used to remove organics, kill parasites and flukes, and treat topical bacterial infections as a paste.
  • Trichlorocide – this is a broad-spectrum fluke and lernea/argulus killer and an organophosphate. It is easy to use and easy to come by and can replace BOTH dimlin and fluke tabs. Hint: know how to use organophosphates.
  • Hydrogen Peroxide – to neutralize potassium permanganate treatments.
  • Chloramine-T – An in-water medication used for the treatment of gill infections.
  • Clove Oil – Used to temporarily knock out a fish for easy of treatment. Do not use in the q-tank directly but in a separate container.
  • Injectable medications. Obtain these from a licensed veterinarian.

5. Water: One of the most easily overlooked of the required q-tank elements is water. Keep in mind that two of the major goals of the q-tank process are to reduce the stress of the new fish and prepare him for the new pond. For a new fish, initially any source water can be used as long as it is properly treated (chlorine, pH, and KH). No matter what you use, the new fish will hate it and try to jump out and walk home. As you get closer to putting the fish into the main pond, you might want to consider using pond water during water changes so the fish can adjust to the pond’s environment. However, no matter what source water you use, routine water changes, daily monitoring of ammonia and nitrite levels as well as weekly testing of KH levels will be needed.

If you are managing a sick fish from your pond, you should only use pond water in an effort to reduce the stress levels of moving the sick fish to the Q-tank facility.

6. A Buddy: Keep in mind that koi and goldfish are schooling animals and as such, are happier when they have buddy in the tank. If you have purchased just a single fish, then get a volunteer from the pond to keep the fish company. Goldfish, no matter what size, make good tank buddies for koi. Also, a healthy tank buddy also provides an indicator of behavior in the tank. If the new fish sulks and the tank buddy does not, it may indicate a problem with the new fish.

  • Placement of the Q-tank. The physical location of the q-tank should be considered carefully and for the following reasons:
  • Ease of maintenance (water changes, access, etc.)
  • Safety/predator control
  • Sunlight/temperature control

Managing the Q-Tank Process

Now that you have amassed all the components of a good Q-tank facility, it is time to exercise the Q-tank process. The following is a day-by-day schedule for managing the Q-tank process. Certainly this is not cast in stone and can be altered to meet specific needs, but consider the basic procedures used throughout the schedule:

Day One: Once you have set up your q-tank and added and treated the water, you are ready to add your fish. At this point, you should have a .1% salt level in the water, Amquel or Prime treating the chlorine and ready for the ammonia, a KH level of at least 100 and the pH within the 7-8.5 range. Add the dimlin or Anchors Away. Note this in your journal.

Assuming the fish is in a transport bag, make sure that the water temperatures between the bag and the q-tank are within 5 deg F of each other. If not, float the bag in the tank until the temperatures are within 5 deg F.

It is advisable to NOT add the water from the bag to the q-tank. Whatever the fish is bringing with it is in the bag water and so let’s reduce the odds of problems and just pick the fish out of the water and turn it loose. Thoroughly clean the bag and save it for later.

The fish will be immediately unhappy and probably dart around a bit and then settle into a dark quiet place. No matter how the fish reacts, cover the tank tightly as in short order, the fish will attempt to leave.

Do not feed or even try to feed. Let the fish settle down and get accustomed to the new tank and water.

Observe the fish’s behavior closely and often. Some things to look for:

  • Make sure that the fish is swimming level and can maintain a proper attitude when at rest.
  • The gill movement on each side is even and not labored.

Day 2 or 3: Once the fish has settled down and appears to be acting normally, it is time to do the initial exam of the fish. Depending on how experienced you are with handling fish or how big the fish is, you may wish to use the transport bag or a shallow tub for this process. At a minimum, perform the following tasks:

  • Check water parameters. This should be a daily procedure and the parameters should be managed accordingly. Note the water parameters in your journal. Include water temperature.
  • Raise the salt level to .2%.
  • A general external exam, checking the fins, mouth area, skin and gills, eyes, etc. Also feel the belly and make sure it is firm. Check for visible macroparasites, such as lernea and anchor worms. Note the results of this exam.
  • Next, exam the gills. The easiest way is to slip your thumb under the gill cover and raise it gently. The gills should be blood red. It is not uncommon for a stressed fish to expel blood from its gills during handling. Also, what appears to be hunks of gill material may also appear in the blood. Do not panic. While this is not a good thing it is a common occurrence. The increased blood pressure caused by stress forces blood out from the capillaries in the gill filaments and normal clotting of the blood causes the appearance of hunks of gill material.
  • Using a microscope slide, scrape the fish’s mucous covering from tail to gills along the lateral line and under the chin, from mouth to pectoral fins. Use a cover slip to evenly spread the mucous coating on the slide and then cover the specimen and examine under the scope. Obviously we are looking for anything that is moving, such as parasites and flukes. This is a critical step in the q-tank process as this will dictate a more solid routine to follow in the next couple of days. Without this step, we have to assume that the fish as parasites and flukes.
  • Last, check the fish feces. The fresher the feces, the better. Typical feces is either light gray or brown (depending on the diet), narrow and tubular and firm. If the feces is whitish and stringy, this is an indication of a possible internal parasite problem. A microscope study of fresh feces is always an interesting ordeal and quite revealing in the health of the fish.
  • Feed sparingly, but do not expect him to eat. If the food is still in the water after one hour, remove it.


Day 4 or 5: This time frame begins the treatment of the fish for parasites, flukes, etc. As stated, the microscope study from Day 2/3 should dictate the routine to follow but if this has not been done, we have to assume that the fish has EVERYTHING. And this is not a bad assumption and as such, treatment for all conditions should be performed.

  • Perform the first water change (minimum 50%) and treat the water accordingly.
  • Salt levels should be raised to .3%. This level will be maintained for the next couple of weeks.
  • Check the fish’s behavior. By this point he should have settled down and acclimated to his environment.
  • Add the fluke tabs. Record this in your journal by date.
  • Continue to feed lightly.

Day 6 or 7: These are “maintenance days” and the following needs to be performed:

  • Check water parameters and treat accordingly.
  • Scrape and scope the fish. Note the results in your journal.
  • Check the gills.
  • Look for and exam fresh feces.

Day 8 through 12: Assuming that the scope studies show nothing and the fish’s behavior is normal, you can start planning for the fish’s release. To do this, perform the following:


  • Perform a 50% water change using pond water. This will begin to acclimate the fish to the main pond’s condition.
  • Maintain a .3% salt level.
  • If you plan on performing a potassium permanganate treatment prior to release, manage ammonia levels with water changes from the pond. Do not use Amquel, Prime or other de-chlorinating products as this will neutralize the PP treatment immediately.
  • Observe the feces. No need to do a scope exam unless the feces are irregular.
  • Continue to feed lightly.

Day 13 or 14: Last days in captivity. Prior to release, perform the following:

  • Complete a thorough physical exam, especially the gills.
  • Optionally, perform a q-tank-wide PP treatment at 2PPM. Leave the pump and filter running as this will provide a nice sterilization process. Neutralize the treatment after 8 hours with hydrogen peroxide or Amquel.
  • Alternatively, perform a .6% salt bath for 30 minutes (unless fish is too stressed)
  • Release to pond.
  • Enjoy!

Additional Thoughts: As stated early on in this chapter, these procedures are not set in stone and really offer practical guidelines for meeting the goals of a new fish from the dealers environment to your pond safely and healthy. Certainly we could not cover all the problems that one can encounter in a q-tank process, such as advanced health problems, injectable medications, etc. and for these types of situations, let me offer the following resources on the web:

  • The Associated Koi Clubs of America (AKCA) – www.akca.org
  • Dr. Erik Johnson, DMV, web site – www.koivet.com

Both web sites offer bulletin boards supported by some of the best and most helpful koi health advisors and specialists around. Do not hesitate to ask your question on these bulletin boards. When it comes to health problems, time is always of the essence.

And finally, it is my experience that pond-wide koi health problems just do not “happen”- something caused them. The occasional ulcer or fin rot is too explainable. But when it comes to massive fish kills or pond-wide health problems, THE MOST COMMON reason for these sad events is usually linked DIRECTLY back to the owner’s failure to properly quarantine and treat new fish prior introducing them to the pond. For all of us that have seen massive fish kills from poor quarantine procedures, we have heard all the excuses like:

  • “But they looked healthy…”
  • “I trusted my fish dealer… his fish are healthy.”
  • “I was told this was not important.”
  • “I didn’t know.”

The quarantine and treatment of new fish is probably the single most important activity koi owners need to do to ensure the health of their ponds and fish.