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FISH / new pets

Koi Care Guide

Tips from home to health to food and fun

Overview

6 things to know about your koi

  • Experience Level: Intermediate
  • Size: Koi grow up to 36 inches (91 cm) long
  • Lifespan: They can live for more than 50 years and thrive in a wide range of water temperatures
  • Temperament: They are generally peaceful but may pick on slower fish
  • Origin: They're a type of carp native to Japan
  • Did You Know: Koi can learn to recognize and take food from their pet parents

How do I set up my koi's aquarium?

  • Koi grow quickly and get very large. Keep mature koi in an outdoor pond of at least 3 feet deep, with at least 50 gallons of water per fish.
  • Young koi can be kept indoors in an aquarium of at least 29 gallons.
  • Put the aquarium in a quiet area out of direct sunlight and drafts.
  • Cover the aquarium with a hood to reduce evaporation and splashing and to keep fish from leaping out.
  • To transfer new koi to the aquarium, float them in the water inside their bag for about 10 minutes so they can acclimate to the new water temperature.
  • If you're introducing koi to an existing school in an aquarium or pond, quarantine the new fish in a separate body of water for 2 to 4 weeks to be sure they are healthy.
  • On moving day, use a net to transfer the koi so old water doesn't mingle with new water.
  • Whether they live indoors or outdoors, add no more than 3 new koi at a time.
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Filtration

  • Follow the manufacturer's instructions for choosing and setting up the right size filter for your koi habitat.
  • An aquarium filter should be able to process all of the water in the tank 3 to 5 times an hour. For example, the filter in a 20-gallon tank would need to push through at least 60 gallons of water each hour.
  • Add beneficial bacteria supplements to help break down waste in the habitat.
  • PetSmart offers free aquarium and pond water testing. Just bring in a sample of your water, and we can test the quality within minutes.
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Heat & light

  • Outdoor koi are hardy and will hibernate under ice in winter as long as their pond is deep enough to not freeze completely. (They won't survive in solid ice.)
  • Your koi's pond should be partially shaded.
  • Indoor koi prefer water between 65 and 75 degrees Fahrenheit.
  • Install a light inside an indoor aquarium to illuminate it for 8 to 12 hours a day.

Water temperature

Koi are pretty temperature-resistant— they can even hibernate under ice in winter. Just be sure your pond is at least three feet deep— otherwise, it could freeze solid, and koi aren’t that tough. When they live indoors, koi prefer cool water—between 65 and 75 degrees F (18 to 24 C).

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How do I keep my koi healthy?

If your outdoor koi don't seem to be eating in the winter, don't worry; it's normal for them to stop eating at temperatures below 40 F.

Be sure to contact a veterinarian if you notice any of these symptoms:

  • Unusual swimming pattern
  • Thinness or decreased appetite
  • Abdominal swelling
  • Inflamed or discolored skin or fins
  • Fins clamped to sides of body
  • Scraping body on rocks (flashing)

PET SAFETY TIPS

  • Fish and aquatic animals can transmit disease to humans. Wash your hands with soap and water before and after interacting with your aquarium. Children, pregnant women, elderly people and people with immune-system problems should take extra care.
  • Keep fish away from food and areas where food is prepared.
  • Never release fish into the wild. They won't adapt well and can damage natural habitats.
  • Thoroughly wash your hands with warm, soapy water before and after contact with any pet or its habitat.
  • Adults should assist children with hand washing after contact with a pet, its habitat or aquarium water.
  • Do not use soaps or detergents to clean aquarium or décor, since they are toxic to fish.

VET ASSURED™

Pets purchased at PetSmart are part of our exclusive Vet Assured™ program, designed by PetSmart veterinarians to help improve the health and well being of our pets.

Our vendors meet a high standard in caring for pets and screening them for common illnesses. This program also includes specific standards for in-store pet care.

PETSMART PROMISE

If your pet becomes ill during the initial 14-day period, or if you're not satisfied for any reason, PetSmart will gladly replace the pet or refund the purchase price.