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Koi-Keeping Essentials: Your Quarantine Tub

Jana worked in animal welfare with abused and unwanted pets. She loves sharing her hands-on experience regarding domestic and wild critters.

If you're breeding koi, you'll need a quarantine tub to help keep them safe. Learn all about the purpose of this tub and how to use it.

If you're breeding koi, you'll need a quarantine tub to help keep them safe. Learn all about the purpose of this tub and how to use it.

What You'll Learn About Keeping Koi

  • Why a quarantine tub is a must
  • How to prepare your chosen container
  • How to release koi into the quarantine tub
  • What to expect of the quarantine period
  • Precautions when releasing a quarantined koi into your pond

Why Do You Need a Quarantine Tub?

The quarantine tub is a multi-purpose lifesaver. There are times when a single koi needs to be kept separate from the shoal. It could be injured or show symptoms of a disease. In that case, a quarantine tub serves to protect the pond as well as allow the sick fish temporary accommodation where it can be treated.

The container is a must for newly purchased koi. They need to go through a period of observation and acclimatization. The experience of getting bagged and transported and the different temperature and pH levels in a new environment can all cause stress. This weakens the immune system, inviting bad pathogens to sicken or even kill koi.

How to Prepare the Quarantine Tub

Your chosen container should be large enough to comfortably accommodate a single fish for up to a month. The necessary equipment also needs to fit inside without stealing space. Play around to see what works for you, but the basic tub should be about 30 inches deep and six feet wide. The material must be plastic, such as vinyl or PVC. Don't go too big. The water in a smaller tub is easier and cheaper to medicate.

1. Purchase the Equipment

A big rule is to have separate equipment for your tub. Resist the urge to share any with the pond, or use the pond's, when you need some for the container. Pathogens hitchhike this way. Luckily, everything you need can be found at local pet shops, home improvement stores or online.

  • An air system
  • Filter (consider getting a bead filter, it makes cleaning very easy)
  • Heater and thermometer
  • Bottom drain (there are add-on types available)
  • Netting (prevents koi from leaping out)
  • Enough blue insulation foam to cover the tub's sides and bottom
  • Extras like nets, siphons, strong tape, containers and spares
  • A good water pump that can process between 250 and 400 gallons per hour
  • Dechlorinator (make sure you get an adequate amount, at least one or two gallons)
  • Test strips or kit to test water quality for salt, ammonia and nitrate levels
  • A lot of non-iodized salt as well as kosher salt, the latter being an excellent tonic against external parasites and minor skin problems. Salt must be kept at three percent (obtaining a salt meter can give you an instant reading)
  • If you keep the tub indoors without natural light, consider adding bulbs with full-spectrum UVA and UVB.

2. Choose the Location

Choose the location and install the equipment long before purchasing koi. This allows enough time to complete the set-up, make sure everything's in working order and to “cure” certain elements. For example, new filtration material requires about a week to attract beneficial bacteria. Location should be chosen with the koi's safety in mind. If bad weather and predators loom, indoors is better.

Position for easy access to the fish and ideally, near a bathroom. About 20 to 30 percent of the tub's water must be replaced daily. The old water must be discarded down a drain.

3. Install the Equipment

Once you have everything you need, installation can be done as follows:

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  • Using the tape and foam, completely insulate the bottom and sides of the tub (this is to control water temperature).
  • Place the bottom drain over the edge, then connect the filter to the drain pipes.
  • The water pump inline is next and the outflow tube, if possible, must go over the opposite side of the tub than the drain pipe.
  • Keeping a six-inch space from the top, add water. Include a little pond water (to catch some beneficial bacteria). Dechlorinate any municipal water and add salt if necessary.
  • Turn on the pump and secure each joint.
  • Switch on the heater a few days before your koi arrives. This is to test the heater's capacity to maintain acceptable levels, between 75 and 80 degrees.
Correct handling is important. Koi are normally scooped, very gently, from below. Large koi sometimes need both hands to support the fish.

Correct handling is important. Koi are normally scooped, very gently, from below. Large koi sometimes need both hands to support the fish.

How to Place the Koi Inside

It's safe to assume a newly-purchased koi experiences some stress during capture and transport. There's not much you can do except to keep things comfortable at your end. The key to lessening the shock of a new home and water conditions is to do things slowly.

  1. Equalize the water temperature. Float the plastic bag with the fish inside the tub and after 15 minutes, test with a thermometer.
  2. Compare the pH. After the temperature has equalized, test the pH of both the tub and the bag. The difference cannot be greater than 0.2. If that's the case, add a small amount from the tub to the bag and test again. Repeat until the readings are the same or below 0.2.
  3. After 20 minutes, release the koi. Don't turn the bag upside down. To prevent pathogens from entering your tub, it's better to lift the koi out by hand. Don't use a towel as it could remove the fish's protective coat. For that reason, make sure your hands are wet, before gently sliding your hands under the koi. If possible, do it as low as possible in the tub and near the side to prevent the fish from landing on the ground should it wrestle free.
  4. Once the koi is in the quarantine tub, cover it with netting and turn off any lights. Leave your new pet alone for a few hours to settle in. (Of course, you can discreetly peek now and again!).

A Word of Warning

Open the box containing mail-order koi as quickly as possible. Sometimes—and this is not good—one can be found gasping at the top of the bag.

  • If this is the case, open the bag and let it float as per step one above. If too little oxygen caused the distress, this should cure the gasping and you can retie the bags and let them float until the water temperature equalizes
  • Overly-warm water in the bag is another reason for gasping. Keep the floating bag open until the temperature is sorted.
  • Unfortunately, struggling for air is also a sign of illness. Check for additional warning signs like lack of energy or listing. This is the only time when you can shorten step one. Open the bag, add some of the quarantine water, and keep the bag in an upright, open position for five minutes. Test the pH and release the fish. Keep an eye on your koi to make sure that the problem doesn't persist.
Koi prefer company but not a crowd. If your quarantine tub is big enough, you can keep two or three new fish together.

Koi prefer company but not a crowd. If your quarantine tub is big enough, you can keep two or three new fish together.

The Quarantine Period

For the next three weeks, watch your koi. Record any abnormal behaviour, disease and eating habits. Also, scrub your hands with a proper antiseptic after working with the pond or quarantine tub—and especially before switching between them. Bug hopping at this stage could be disastrous for both. Bolster the immune system of your new pet by keeping the water temperature at around 72 degrees and replacing 20 to 30 percent of the water every day. Remember to dechlorinate any new water.

Releasing Koi Into the Pond

Assess your pet's health. At the end of three weeks, does it look and behave in a healthy manner? If so, then the time has arrived to transfer it to the pond

  1. Compare water conditions between the pond and tub. Temperature must be 70 degrees or higher and mustn't differ by more than five degrees. Similarly, pH values from the two waters must not have a greater difference than 0.2. If the outdoor pond water isn't warm enough, consider leaving your koi in the tub until the days are warmer.
  2. Switch off the quarantine heater. Leave overnight and test the temperature again in the morning. If the pond-tub difference is more than five degrees (but not too much), bag your koi
  3. Use a bowl to catch your fish. Bowls are a gentle method, since it's easy to slip one under the fish. Once caught, pour it into an already partially filled bag. The water volume should accommodate the koi without making the bag too heavy. Tie off with a rubber band.
  4. Float the bag in the pond for around 20 minutes and away from direct sunlight (you don't want cooked koi). Then, release your pet into the pond!

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2018 Jana Louise Smit

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