Koi Fish Care Guide – Diet, Tank Setup & More

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For the last ten years or so, having koi ponds in the backyard has become quite popular.

 People may have had koi fish as pets long before that, but the craze is definitely something new. The question is, do the people who want a trendy koi fish pond actually know how to take care of their fish? 

The answer to this question is that some probably do, and some probably do not. It’s important to know how to care for your koi fish before you actually bring them home. The last thing you want to do is spend hundreds of dollars on fish and supplies only to have the fish die a few days or weeks later.

Koi Fish Lifespan

The good news is that, if you take care of your koi fish, they can live to a ripe old age. In fact, koi fish have been known to live up to 50 years. That’s more than half the average human lifespan. But this is only true if you take good care of them. Some of the mistakes people make when it comes to caring for their koi fish include:

  • They dump new koi fish into a pond that already has other fish in it
  • They don’t dig their pond deep enough
  • They leave their tanks in direct sunlight all day long
  • They don’t lookout for signs that their koi fish are in trouble
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Here, we’ll talk about the basic ways to care for your koi fish. Hopefully, you’re reading this before you go to the pet shop. But, if you already have your fish, you can always commit to taking better care of them.

What Kind of Tanks Should You Keep Your Koi Fish In?

If you’re going to bring koi fish home, you’re probably going to keep them either in a tank or a backyard pond. We’ll talk about each of these for a bit. Most people initially keep their fish in a tank and then transfer them to a pond. We’ll tell you how to safely do this as well.

If You’re Going to Keep Your Koi Fish Inside

If you’ve chosen to admire your koi fish from the comfort of your living room, there are a few things you need to know:

  • Make sure your tank holds at least 29 gallons
  • Keep the tank out of direct sunlight but make sure they do get some sort of illumination for 8-12 hours a day
  • Keep a cover on top. This will make sure the water doesn’t evaporate. It’ll also ensure that your koi fish don’t jump out of the tank.
  • When you’re ready to move your fish, put them in a bag of water for at least 10 minutes so they can get used to the new environment
  • Don’t add new fish to a tank with other koi fish in there. Wait at least 2-4 weeks before you combine your fish.
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Now, if you’re not going to keep your fish indoors and you want to build a koi pond in your backyard, there are some things you need to do:

  • Never add more than 3 koi fish to the pond at any given time
  • Make sure the pond is at least 3 feet deep. Otherwise, the water can freeze in cold temperatures and the fish will die
  • As long as your pond is deep enough, your fish can actually hibernate in the cold water under the top layer of ice. They won’t die.
  • Dig the pond in a part of the yard that gets shade at least half the day
  • Don’t add new fish to old fish. The old fish may try to eat the smaller fish. Koi fish are peaceful but they do take advantage of smaller fish that share their tank or pond.

Whether your fish are in a tank or pond, you want to keep the water temperatures somewhere between 65-75 degrees. 

What Kind of Filter Do You Need?

If you want your koi fish to live a nice, long, life, you need to make sure you invest in a good filtration system. You have to make sure your filter processes all the water at least 3-5 times an hour. So, if your tank holds 20 gallons, your system needs to filter at least 60 gallons of water per hour.

Test your pond water. The only way to do this is to take a sample to your local pet store. Or, you can buy a home test. When you buy your koi fish, you’ll get instructions on what the best water levels need to be. 

What Should You Feed Your Koi Fish?

Koi fish will eat just about anything. Like other household pets, they even like to eat people’s food. Some of the more common things koi fish like to eat include:

  • Small bugs, plants and algae
  • Cereal
  • Lettuce
  • Rice
  • Peas
  • Watermelon
  • Store-bought koi fish food
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How Can You Tell if Your Koi Fish Aren’t Feeling Well?

You want to keep an eye on your koi fish. If they don’t seem to be doing well, you may want to take them to the store. Some of the signs that your fish are struggling include:

  • They’re swimming in strange patterns
  • Their skin is discolored
  • They have swollen abdomens
  • Their fins look pinned to their sides
  • They start to scrape their bodies along the rocks

As long as you pay attention to your fish, they should be okay. But you also want to take some general precautions when it comes to handling and caring for your koi fish.

  • Always wash your hands before and after handling your koi fish
  • Koi fish should not be kept anywhere near where food is prepared
  • Never use soap or cleansers to wash your koi fish tank
  • Never release your koi fish into the wild. They will not survive.

Now that you know how to take care of your koi fish, it’s time to go shopping!

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