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Family: Cyprinidae

Common Name: Koi

Origin: Wild form originates from Eastern Europe and Asia. Coloration believed to have been developed in Japan in the 1800's. Wild type have been released worldwide and have established populations on almost every continent except Antarctica.

Compatibility/Temperament: Very peaceful fish, but they get large and need cold water. They will eat anything that fits in their mouth. Not suitable for home aquaria. Best kept in outdoor ponds with members of its own species or large goldfish.

Koi Diet

Omnivorous. Enjoys treats of boiled peas, Cheeros, and orange slices. High protein diet when water is above 60F. Low protein, high carb diet when water is between 60F and 50F. Do not feed below 50F.


Juveniles can be found in pet stores under 6 inches. Adults top out between 2 and 3 feet.

Minimum Tank Suggestion

1000 gal

Water parameters for Koi

pH range: 7.0 - 7.5, dH range: 10 - 15, temp: 30F - 80F


Other common names for this species are brocaded carp and nishikigoi. Koi are very delightful and rewarding if kept under proper conditions. This is a pond fish and NOT suitable for home aquaria. They will quickly outgrow your tank. When they do, please do not release them into local waterways as they often cause adverse effects in the form of clouded waterways.

The largest difference between koi and goldfish is the presence of barbels near the mouth on koi. An adult koi will also grow much larger than an adult goldfish. Hybridization between the two species is possible and has been observed in the wild and in captivity.

Koi come in many color varieties. Kohaku, white with red splotches of color; sanke, like kohaku but with the addition of small black marks; tancho, a kohaku with the only red being in a circular shape on the head; utsuri, black with either red, yellow, or white blotches of color; ogon, solid white, yellow, or orange. Many more specialized color forms are also available.

When receiving proper care, koi easily live to be 20 years or older. Ideally koi ponds should be at least 3 feet deep and give the fish plenty of swimming room as they get rather large. They will root around on the bottom, so keeping lilies with them is not always easily achieved. Koi are a high waste fish like goldfish, so keeping some plants in the water is beneficial to prevent algae outbreaks. Ponds should also be sufficiently shaded to prevent the water from getting too warm in the summer. If a canopy of tress is present, a net should be draped over the pond to prevent leaves from entering the water. The decaying leaves will sap the oxygen from the water and can cause fish kills.

While koi may be a beautiful fish, it is not an investment for the casual aquarist. They get large and need to be housed in large, outdoor ponds. Japanese refer to them as living jewels. They really can make a pond come alive and give you hours of enjoyment under the right conditions. Always think before you buy.

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The following members have contributed to this profile: thekoimaiden
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