Koi are beautiful fish with a long lifespan and a voracious appetite. They are considered living ornaments in their native Japan and have a devoted following of keepers and admirers. If you chose to join their ranks, you need to know what koi fish eat and when.

Koi fish will eat nearly anything. From pellet food to fresh fruit or crayfish, they will be interested in consuming it, though not all food is beneficial. They are omnivorous fish whose metabolism is driven by the water temperature. The warmer the water, the more frequently the koi fish will need to feed.

What Are Koi Fish?

Koi are domesticated Amur carp, bred selectively for color and pattern as a living showpiece. They are hardy and friendly fish that can grow to over three feet in length and can live for over forty years. The oldest known koi was named Hanako, and she lived for two-hundred twenty-six years. They come in many colors to include red, black, white, yellow, and blue, and also a variety of color patterns. 

What do Koi Eat?

Koi are omnivorous fish that enjoy eating anything that tastes good to them. The preferred (and healthiest) food for koi is specialized pellet food. These pellet foods come in both sinking and floating varieties designed to meet the unique nutritional needs of koi. The pellets also provide vitamins and minerals to help keep the koi’s colors vibrant.

Some human food can be given as a treat. Koi love fruits and vegetables and are very fond of meaty treats like worms and shrimp. Cereals are also a favorite, but any leftovers need to be cleaned out of the pond promptly.

Wild-caught crayfish or other marine life should not be given to koi as a treat as this could bring bacteria and disease into your pond.

When to feed Koi Fish?

Consistency is key when feeding koi. They do not have a stomach and must feed several times throughout the day, especially in warm weather. Koi will get to know their schedule and be waiting at the edge of the pond looking for you. They are very social fish and will eat from your hand after a short while. 

How often to feed your koi is determined by the water temperature. As the temperature drops in ten-degree blocks, the frequency of feeding decreases. When the water temperature drops below forty-one degrees, feeding must stop altogether as the fish will be in hibernation. If koi hibernate with undigested food in their stomach, it can rot and cause infection.

Over 86°F: Feed no more than 2 times daily
68-86°F: Feed 2 to 4 times daily
59-68°F: Feed 1 to 2 times daily
50-59°F: Feed no more than 2 times daily
41-50°F: Feed no more than 2-3 times weekly

History of Keeping Koi

Originating in the Niigata region of Japan, koi are mentioned in historical records since 620 AD. Originally kept as a food source, the selective breeding of koi fish for color patterns began in the 1820s. They were relatively unknown outside Japan until a Tokyo exhibition in 1914. Now, koi are found in nearly every country worldwide and are considered a symbol of love and friendship. Koi are also the unofficial national fish of Japan.

Keeping Koi

Koi need a well-aerated pond with good water quality. The pond must have a portion that exceeds five feet deep in northern climates to keep the fish from freezing. The pond must also have sides high enough to keep predators like raccoons from catching your lovely fish. Herons and others birds can be a threat too, so netting may be required above your little oasis to prevent “flying fish”.

Into the Wild

Whether on purpose or by accident, koi have been released into the wild on every continent besides Antarctica. They are an invasive species in many places because they stir up the mud enough to render the water undrinkable. They are also frequently stocked in golf course ponds to control insect larvae. 

They can thrive in the wild, though they will lose the bright colors after a few generations. Koi can grow big in the wild as well. Some friends of mine spotted a nearly three-foot-long and healthy example while bow fishing a Michigan river for carp. 

Conclusion

Koi are beautiful and friendly fish that can be fun to keep as a pet. If you feed them right and pay attention to the water temp in your feeding schedule, they will provide enjoyment for generations. 

Brandon Tanis