What are Koi?

The colorful koi fish, called nishikigoi in Japanese, is a specially bred variety of carp. Carp can be found all over the world in cool water, and are pursued for sport and for food. In the 19th century, Japanese farmers began breeding decorative carp, selecting brightly colored specimens to ornament gardens in luxurious fish pools. These fish can be found all over the world in decorative gardens and in a dizzying variety of colors, shapes, and sizes. Although they resemble oversized goldfish, sometimes growing up to three feet (91 centimeters) in length, the two fish are related only distantly.

In Japan, the term “koi” refers to carp. The fish known in English as koi are actually nishikigoi, “brocaded carp,” a reference to their colorful patterns. In Japan, the fish are considered to be lucky symbols of friendship and affection. They were introduced to the world in 1914 during an exposition, and quickly became popular decorative pets, especially when the introduction of plastic bags and rapid shipping made shipments of the valuable fish viable. Some particularly distinctively patterned fish sell for thousands of dollars.

In Japan, koi are differentiated by pattern. The most popular is the Kohaku, a white skinned fish with a red upper pattern. Other varieties include the Tancho, a white fish with a red dot on its head, Showa, a black fish with white and red spots, and Ogon, a solid colored fish which can be flat or metallic. Numerous other named types of koi can be found at dealers, and more are constantly being introduced through careful selective cross-breeding and breeding with wild carp.

These fish are cool water fish, and prefer deep ponds so that they can sink to the bottom in hot weather. They can be lured to the surface of a pond with food, and can also be taught to recognize people and taken food from their hands at feeding times. People who keep koi feed them with specially balanced food that floats, encouraging the fish to surface so that they can be checked for potential signs of illness.

Many Japanese ornamental gardens feature a koi pond which is surrounded by lush foliage and benches to sit and contemplate. Similar pools can also be found in a variety of other locations, and the hardy fish do well in a wide range of environments. Breeders recommend that the pools be shaded, so that they do not grow too warm and so that the brightly colored fish cannot be seen from overhead by predators. In addition, a pond that is not protected from predator species should be built with overhangs for the koi to hide under.

Frequently Asked Questions

What exactly are koi fish?

Koi, known scientifically as Cyprinus rubrofuscus, are ornamental varieties of domesticated common carp. They are bred for their vibrant colors and patterns and are popular in outdoor ponds and water gardens. Originating from East Asia, koi have been selectively bred for centuries, with the practice becoming particularly refined in Japan.

How long do koi fish typically live?

Koi fish are renowned for their longevity. With proper care, they can live for several decades, and some have been known to live over a century. According to a study published in the journal "Aquaculture," the average lifespan of koi in a well-maintained pond is around 25 to 35 years, highlighting the commitment required for their care.

What do koi fish eat?

Koi are omnivorous and have a diverse diet that can include algae, plants, insects, and specially formulated koi food that provides balanced nutrition. High-quality koi food typically contains a mix of proteins, carbohydrates, vitamins, and minerals to ensure the fish maintain their health and vibrant colors.

Can koi fish recognize their owners?

Yes, koi fish are known for their intelligence and can recognize their owners. They can be trained to eat from a person's hand and may exhibit excited behavior when they see familiar individuals approaching. This level of interaction adds to their appeal as pets and pond inhabitants.

What is the significance of koi fish in culture?

Koi fish hold significant cultural importance, especially in Japan, where they symbolize love, friendship, perseverance, and good fortune. The koi's ability to swim upstream is often likened to a person's ability to overcome obstacles, making them a popular motif in art and literature.

How can you tell the age of a koi fish?

Determining the exact age of a koi fish can be challenging without historical data. However, size and growth rings on their scales, known as annuli, can provide an estimate. As koi grow, they develop these rings annually, much like trees do. A careful examination by an expert can give an approximation of a koi's age.