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Home > Fish > Blue Koi Fish: Facts, Origin & History (With Pictures)

Blue Koi Fish: Facts, Origin & History (With Pictures)

Blue Koi Fish

Koi fish are available in many different colors and patterns, but one of the most attractive varieties is the blue Koi fish. Koi fish make lovely additions to many ponds and water gardens, where they add color and variety. One of the many colors Koi can be found in is blue, and it is considered more valuable than the standard colors of Koi.

Length: 20–28 inches
Weight: 9–16 pounds
Lifespan: 25–35 years
Colors: Blue, white, black, yellow, orange, cream
Suitable for: Large ponds and water gardens
Temperament: Peaceful and social

The Blue Koi itself is not a variety of Koi fish, but it rather describes Koi with blue markings. The coloration is generally associated with Japanese Koi, which are some of the most well-bred Koi fish in the world.

The blue coloration is typically mixed with other colors to form a pattern on the koi’s body, as it is not common to find a Koi that is a solid blue color. In some cases, the Koi’s colorful markings may have a blue hue in direct lighting, but not appear blue at first glance. This can sometimes give a blueish-black or purple appearance, which is a striking coloration for Koi to have.

Some varieties of Koi, such as the Asagi Koi have a blue-grey body, with other colored patterns on their bodies such as red or deep orange.

Blue Koi Fish Characteristics

Ease of Care

The Earliest Records of the Blue Koi Fish in History

Most of the earliest records of Koi being domesticated were in China in the 4th century, but only in the 19th century in Japan. The Blue Koi fish specifically is a type of Japanese Koi that originates from eastern Asia in Japan.

All of the Koi fish we see today descended from Amur carp, which is a type of cyprinid fish found in Asia. These Amur carp lived in the Aral, Black, and Caspian seas before later being farmed in China as a source of food by rice farmers.

These fish were picked for their hardiness and adaptable nature which allowed them to live in rice paddies. It did help that the Koi carp had fast growth and were easy to breed. It is possible that the carp developed color mutations in their wild habitats, but they were likely only recognized when they were being farmed. The carp’s color mutations made the once greyish-bronze fish develop more vibrant colors and patterns.

Through selective breeding by the Japanese in the early 1800s, Koi are now available in many different varieties and colors that were limited during their early recordings. Early records show that Koi have a symbolic meaning in Japanese culture, and they are an inspiration behind many Chinese and Japanese artworks.

All sorts of new colors were being produced by the Japanese Koi breeders aside from the common red and white coloration. The development of blue was noticed too and desired in Japanese Koi fish. Certain varieties of Koi are well known for having blue color combinations on their body. It is possible that the blue color mutation already developed in wild populations before being noticed by the Japanese.

How the Blue Koi Fish Gained Popularity

When Japan was invaded by the Chinese, carp were still being bred as food. This is the main theory of how these colorful carp made their way into Japan and it was the start of new varieties of Koi fish being created.

When Koi made their way into Japan, they were bred for their colors and variety. It wasn’t until the early 1900s that Koi started to catch people’s interest. This is likely due to a Tokyo exhibition in 1914. It showcased brilliantly colorful Koi fish caught that the interest of an Emperor, who was gifted Koi fish for his moat. This is believed to be the start of the Koi fish’s popularity.

Koi fish were soon desired in Japan, and they were not only kept by Emperors but soon by people all around the world. The Koi’s profound popularity led to the creation of new Koi fish varieties, such as the Asagi, Kohaku, and Utsuri. Koi were found in white, black, blue, red, and cream varieties. Certain color combinations and fin types were more popular than others, specifically because of their rarity and desirability. Blue is a color that is desirable in Koi fish and can be seen in many Koi varieties.

Formal Recognition of the Blue Koi Fish

Since the Koi fish’s popularity, there have been several clubs and societies that have been created to appreciate the Koi fish. These clubs and societies can be found around the world, from Alabama up to Washington State. Florida and California seem to have the largest establishment of Koi clubs and water garden societies.


Top 3 Unique Facts About the Blue Koi Fish

1. Asagi Koi Naturally Have a Blue Coloration

Perhaps one of the most common examples of a Koi fish variety that has blue as a standard coloration is the Asagi. The Asagi Koi have a netting-like pattern on their backs that is dark blue. In some cases, the Asagi’s blue markings may appear black until the fish is moved into a brightly lit environment. This variety of Koi fish was developed roughly 200 years ago and although their coloration may look plain, they are one of the varieties that have a characteristically blue color.

2. Blue Koi Fish Can Grow To 36 Inches in Length, Sometimes Larger 

Nearly all Japanese Koi fish can grow to a whopping length of 36 inches. As a descendant of the large Amur carp, many Koi fish can grow to very large sizes if the environment allows it.

3. Blue Is a Rare Color Found In Koi Fish

Many of the more standard Koi fish colors include red, white, black, and cream. The blue coloration can be found on few Koi fish and is considered rare.

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Does a Blue Koi Fish Make a Good Pet?

Koi makes good pets if you can meet their care requirements. Since Koi can grow quite large, you will need to ensure that their pond size is appropriate. Although it is possible to start raising young Koi in large aquariums, ponds and water gardens are ideal for most juvenile to adult Koi.

A pond size of 1,000 gallons is usually ideal for several small to medium-sized Koi fish. The larger the pond is, the more room is giving your blue Koi fish to grow and reach their full adult size. Once you have gotten the pond size right and ensured that the water quality is good, their care is fairly simple onwards.

A healthy and balanced diet is beneficial for these fish. Choosing a pelleted food that has color-enhancing properties can help with the vividness of your Blue Koi fish’s colors. The pond should be equipped with a pond and filter to prevent the water from becoming stagnant and create an unideal environment for the Koi fish.



Blue is a valued color in Koi fish, and only a few varieties naturally have a blue color. Blue Koi fish are not a variety of Koi, but rather a color of Koi markings. They are descendants of Amur carp in China, but the blue coloration was likely developed by Japanese breeding. When kept in the right environment consisting of a large pond and a filter, and fed a healthy diet, Blue Koi fish can grow up to 36 inches and live for over 20 years.

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