How to Keep Koi Fish in an Aquarium

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Fish for outdoor ponds can live inside the home, and koi fish are one popular example when adopting a pet. Keeping koi in a tank requires some careful planning, as these piscine picks are used to swimming in lots of water. When considering a koi for a family pet, keep in mind that a 50-gallon fish tank (or bigger) may be necessary for housing this particular creature. You can always ask your pet's vet for guidance when it comes to mini koi fish for aquariums.


Koi can live in a tank.
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Keeping koi in a tank

Koi in fish tanks need room to cruise the waves, so be certain the aquarium you're considering is the appropriate size. Since koi typically live in large ponds, bringing one inside means you'll need to set up a tank that provides 24 square inches of water for every inch of fish you have. A too-tight tank can frustrate your fish, so when in doubt, err on the larger size for your tank.


Find a sturdy table

Be sure to set up your hefty tank on a stable surface that won't get bumped or tipped over by passing dogs or toddlers. The aquarium should also reside in a spot that's free of drafts or cool breezes and away from windows, as both can affect the water's temperature. Don't forget about ambient noise around your fish's home. Radios, TVs, and other loud appliances can interfere with the way fish communicate with each other over low-frequency sound waves.


Feeding your koi fish

As tempting as it may be, don't overfeed your fish with the intention of rewarding him or making sure he has enough to snack on if he's hungry later. Aim to feed your koi twice a day or so and only offer the amount your gilled guy can consume in about five minutes. Remember that too much food in a 50-gallon fish tank can dirty the water since it breaks down into harmful substances, including nitrites, nitrates, and ammonia.


When serving your fish's meal, make sure it's fresh. Any flakes or pellets that are older than six months should be tossed in favor of new food that's stored in a tightly closed container kept in a cool, dark spot.

Offer quality water for koi

The top reason fish fall ill and die is due to poor water quality. This situation can be quickly remedied by using a liquid test kit to check the water you'll be using. Each species of fish requires the proper ranges of certain parameters in their water, including alkalinity, water hardness, and the amount of ammonia, nitrites, and nitrates.


Once the water quality is regulated for your particular pet, the next step for keeping koi in a tank is to note the temperature. Koi thrive in water temperatures that are wide-ranging, from 35 degrees Fahrenheit up to 86 degrees, but your indoor tank's water will likely hover in the 68- to 76-degree sweet spot.


Make your koi's home fun

As with any pet, entertainment is an important part of keeping yours happy and healthy. While your fish won't play fetch with you the way your rescue pup might, offering koi in fish tanks a few decorations is a wise move. These little houses shaped like sunken ships or fake plants with floating tendrils offer your fish places to hide out or rest when she needs a break.


Some fish will dig around in the rocks that line the bottom of your tank in order to build a nest. Just be sure these structures you plan to add are cleaned first. Skip metal objects because they'll end up rusting in the water.