Placing a quarantine tank in your pond is great when you don’t have extra space outdoors to use. Since you will be floating the tank in the pond water you will need something that has a rim around the top of it. The rim will hold in oxygen for the fish.
Supplies that you will need are:
• A container to use as the tank. The size of the container will depend on how many Koi and their size. I would suggest a children’s swimming pool. You can pick one up at a yard sale or even very inexpensively at the store. Another idea is a plastic storage container. Rubbermaid or other brands will work. Do not use latex because it is toxic to the fish. Metal is another material that you can’t use. Remember, whatever you use will work best if it has a lip around the top of the “tank”. You will be using the water from your pond to fill your new quarantine tank.
• An air or water pump will be needed to aerate the water. Instructions will come with the air or water pump. Follow those for installing your pump.
• A cover for the tank is needed. New fish like to jump and I’d hate to see you lose your fish before it makes it to the Koi pond. You can use netting or a window screen. Something will be needed to sit on the screen and hold it down. If your fish are large make sure it is heavy enough that the fish can’t push it off when jumping. If you are using netting, be sure it is pulled tight so that the fish don’t jump and get caught between the tank and the net.
• Shade is required since the tank isn’t nearly as deep as your pond. Suggestions are cloth, umbrella, or floating artificial plants if there isn’t any shade available. If you cover the pond with something solid there must be a hole for the release of gasses.
Since you won’t be using a biological filtration system there are some other things that must be done to have good water quality.
• A 50% water change is needed daily. To do this, attach a hose to the water pump and shoot the water outside of the tank and pond. To refill the tank you will sit the pump in your pond, attach the hose and direct the flow of water back into the tank. Being close to the water source makes this much easier. If the quarantine tank is for sick fish be sure to add medication when you change the water.
• Koi can go a couple of weeks without food. Since much of the water problems are from uneaten food and Koi waste you can withhold food during this time. If you must feed the fish, wait at least 2-3 days and feed them very small amounts.
• Test for ammonia and nitrites. Take action immediately to fix bad readings. Your water should be good if the water is changed daily and the fish are not being fed.
A heater will not be required since the tank is sitting in the pond water. It will keep the water in the tank at the same level as long as the tank isn’t in direct sun without any shade.