How to Raise Koi

Those colorful fish you frequently see in large ponds in Japanese restaurants or shopping areas are becoming increasingly popular as the centerpiece of a backyard garden. The brightly-colored fish are called Koi, and they are the result of selective breeding of German and Asian carp. If you are considering installing a Koi pond, you should first study how to raise Koi.


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    Select a proper pond. You can purchase a Koi pond made of several different materials from pet stores or Koi specialty retailers. A good rule of thumb is that the Koi pond measurements should be at least 3 feet (0.914 m) deep and contain 300 gallons (1136 liters) per fish. You may want to get a larger pond than you need right away, so that you can add additional fish later.
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    Purchase the Koi. You can purchase Koi at online retailers, at specialty Koi farms, or in some cases at pet stores. Healthy Koi are not too lethargic or too energetic and swim vertically in the water. If possible, inspect your fish before purchasing them. A healthy fish is more important than a pretty pattern.
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    Feed your Koi. Koi are omnivores. They eat a variety of fish foods and can eat cereal, vegetables, worms, and fruit. You can also purchase special Koi food. Some specialists recommend varying the food - even if it is just Koi food pellets, because some Koi will not eat newly introduced foods if they have become accustomed to a particular type of food.
    • In warmer weather, you can feed a Koi a small amount of food several times per day. Koi have a very small digestive tract, so you need to control the amount of food you give them.
    • In cooler weather, you only need to feed your Koi once per day.
    • Koi enter a hibernation process when the water temperature falls below about 46 F (7.7 C). It is not necessary to feed Koi when water temperatures are this low.
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    Keep the water fresh. While some Koi ponds are large enough to be naturally aerated, pumps and filters can ensure that the water in which your Koi live stays fresh. You may want to consider using Koi pond water additives. Two examples of additives are products designed to keep the water healthy and free of pests. (Remember to be careful what you add to your water solution, as it could potentially hurt or even kill your fish. I.e. Pesticides, Removers, etc.)
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    Be conscious of potential health problems. To produce their spectacular colors, Koi are very inbred and have been for more than 200 years. Because of this inbreeding, domesticated Koi have weak immune systems. Common problems can be noted by watching the Koi at feeding time. Lethargy, a lack of feeding, or seclusion from other fish can indicate a problem. Koi are also vulnerable to parasites or to bacterial infection if they have received an injury. The primary key to a healthy Koi is clean water. If possible, quarantine a sick fish in a separate body of water. If the fish does not seem to be getting healthier, consult a veterinarian who treats fish.


  • Koi that are less than four inches long seem to thrive when treated like a common goldfish, but make sure to put them in a tank containing five or more gallons or they will be too cramped to thrive.
  • It is easier to kill a Koi by overfeeding than by underfeeding. When in doubt, feed the fish less or none at all.
  • Koi never sleep, so feeding them at night would be helpful for faster growth.

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Categories: Fish