Koi


Koi or more specifically jinli or nishikigoi, are colored varieties of the Amur carp that are kept for decorative purposes in outdoor koi ponds, water gardens or aquariums.
Koi is an informal group name of the colored variants of C. rubrofuscus. Several varieties are recognized by the Japanese. Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, and cream. The most popular category of koi is the Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.

History

are a large group of fish originally found in Central Europe and Asia. Various carp species were originally domesticated in East Asia, where they were used as food fish. Carp are coldwater fish, and their ability to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations, including Japan. Natural color mutations of these carp would have occurred across all populations. Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp led to the development of the goldfish.
The Amur carp, a member of the cyprinid family species complex native to East Asia, was aquacultured as a food fish at least as long ago as the fifth century BC in China, and Jin Dynasty texts mentioned carp with various colors. The Amur carp was previously recognized as a subspecies of the common carp, but recent authorities treat it as a separate species under the name C. rubrofuscus.
Amur carp were first bred for color in Japan in the 1820s, in the town of Ojiya in the Niigata Prefecture on the northeastern coast of Honshu Island. The outside world was unaware of the development of color variations in Japanese koi until 1914, when the Niigata koi were exhibited at an annual exposition in Tokyo. From that time, interest in koi spread throughout Japan. From this original handful of koi, all other Nishikigoi varieties were bred, with the exception of the Ogon variety, which was developed relatively recently.
The hobby of keeping koi eventually spread worldwide. They are sold in many pet aquarium shops, with higher-quality fish available from specialist dealers. Collecting koi has become a social hobby. Passionate hobbyists join clubs, share their knowledge and help each other with their koi.

Etymology

The words "koi" and "nishikigoi" come from the Japanese reading of Classical Chinese words 鯉 and 錦鯉 respectively. In both languages, the former can refer to many Asian carp species. In Japanese, "koi" is a homophone for another word that means "affection" or "love", so koi are symbols of love and friendship in Japan.
The first mention of the word "錦鯉" dates back to Tang Dynasty China in a poem by Lu Guimeng :

Taxonomy

In the past, koi were commonly believed to have been bred from the common carp. Extensive hybridization between different populations, coupled with widespread translocations, have muddled the historical zoogeography of the common carp and its relatives. Traditionally, Amur carp were considered a subspecies of the common carp, often under the scientific name C. carpio haematopterus. However, they differ in meristics from the common carp of Europe and Western Asia, leading recent authorities to recognize them as a separate species, C. rubrofuscus. Although one study of mitochondrial DNA was unable to find a clear genetic structure matching the geographic populations, others based on mtDNA, microsatellite DNA and genomic DNA found a clear separation between the European/West Asian population and the East Asian population, with koi belonging in the latter. Consequently, recent authorities have suggested that the ancestral species of the koi is C. rubrofuscus or at least an East Asian carp species instead of C. carpio. Regardless, a taxonomic review of Cyprinus carp from eastern and southeastern Asia may be necessary, as the genetic variations do not fully match the currently recognized species pattern, with one study of mtDNA suggesting that koi are close to the Southeast Asian carp, but not necessarily the Chinese.

Varieties

Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. Although the possible colors are virtually limitless, breeders have identified and named a number of specific categories. The most notable category is Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.
New koi varieties are still being actively developed. Ghost koi developed in the 1980s have become very popular in the United Kingdom; they are a hybrid of wild carp and Ogon koi, and are distinguished by their metallic scales. Butterfly koi, also developed in the 1980s, are notable for their long and flowing fins. They are hybrids of koi with Asian carp. Butterfly koi and ghost koi are considered by some to be not true nishikigoi.
The major named varieties include:
were developed in China more than a thousand years ago by selectively breeding Prussian carp for color mutations. By the Song dynasty, yellow, orange, white, and red-and-white colorations had been developed. Goldfish and Prussian carp are now considered different species. Goldfish were introduced to Japan in the 16th century and to Europe in the 17th century. Koi, though, were developed from Amur carp in Japan in the 1820s. Koi are domesticated Amur carp that are selected or culled for color; they are not a different species, but a subspecies, and will revert to the original coloration within a few generations if allowed to breed freely.
The length of a koi can average up to about 3.28 feet. On average they also grow about 2 centimeters per month. On the other hand, goldfish may only grow to be around a foot. In general, goldfish tend to be smaller than koi, and have a greater variety of body shapes and fin and tail configurations. Koi varieties tend to have a common body shape, but have a greater variety of coloration and color patterns. They also have prominent barbels on the lip. Some goldfish varieties, such as the common goldfish, comet goldfish, and shubunkin, have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Goldfish and koi can interbreed; however, as they were developed from different species of carp, their offspring are sterile.

Health, maintenance, and longevity

The Amur carp is a hardy fish, and koi retain that durability. Koi are coldwater fish, but benefit from being kept in the range, and do not react well to long, cold, winter temperatures; their immune systems are very weak below 10 °C. Koi ponds usually have a metre or more of depth in areas of the world that become warm during the summer, whereas in areas that have harsher winters, ponds generally have a minimum of. Specific pond construction has been evolved by koi keepers intent on raising show-quality koi.
The bright colors of koi put them at a severe disadvantage against predators; a white-skinned Kohaku is a visual dinner bell against the dark green of a pond. Herons, kingfishers, otters, raccoons, mink, cats, foxes, badgers, and hedgehogs are all capable of emptying a pond of its fish. A well-designed outdoor pond has areas too deep for herons to stand, overhangs high enough above the water that mammals cannot reach in, and shade trees overhead to block the view of aerial passers-by. It may prove necessary to string nets or wires above the surface. A pond usually includes a pump and filtration system to keep the water clear.
Koi are an omnivorous fish. They eat a wide variety of foods, including peas, lettuce, and watermelon. Koi food is designed not only to be nutritionally balanced, but also to float so as to encourage them to come to the surface. When they are eating, koi can be checked for parasites and ulcers. Naturally, koi are bottom feeders with a mouth configuration adapted for that. Some koi have a tendency to eat mostly from the bottom, so food producers create a mixed sinking and floating combination food. Koi recognize the persons feeding them and gather around them at feeding times. They can be trained to take food from one's hand. In the winter, their digestive systems slow nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Feeding is not recommended when the water temperature drops below. Care should be taken by hobbyists that proper oxygenation, pH stabilization, and off-gassing occur over the winter in small ponds, so they do not perish. Their appetites do not come back until the water becomes warm in the spring.
Koi have been reported to achieve ages of 100–200 years. One famous scarlet koi named "Hanako" was owned by several individuals, the last of whom was Komei Koshihara. In July 1974, a study of the growth rings of one of the koi's scales reported that Hanako was 226 years old. Some sources give an accepted age for the species at little more than 50 years.

Disease

Koi are very hardy. With proper care, they resist many of the parasites that affect more sensitive tropical fish species, such as Trichodina, Epistylis, and Ichthyophthirius multifiliis infections. Water pH is important for maintaining koi's health. Water changes help reduce the risk of diseases and keep koi from being stressed. Two of the biggest health concerns among koi breeders are the koi herpes virus and rhabdovirus carpio, which causes spring viraemia of carp. No treatment is known for either disease. Some koi farms in Israel use the KV3 vaccine, developed by Prof. M. Kotler from the Hebrew University of Jerusalem and produced by Kovax, to immunise fish against KHV. Israel is currently the only country in the world to vaccinate koi against the KHV. The vaccine is injected into the fish when they are under one year old, and is accentuated by using an ultraviolet light. The vaccine has a 90% success rate and when immunized, the fish cannot succumb to a KHV outbreak and neither can the immunised koi pass KHV onto other fish in a pond. Only biosecurity measures such as prompt detection, isolation, and disinfection of tanks and equipment can prevent the spread of the disease and limit the loss of fish stock. In 2002, spring viraemia struck an ornamental koi farm in Kernersville, North Carolina, and required complete depopulation of the ponds and a lengthy quarantine period. For a while after this, some koi farmers in neighboring states stopped importing fish for fear of infecting their own stocks.

Breeding

When koi naturally breed on their own they tend to spawn in the spring and summer seasons. The male will start following the female, swimming right behind her and nudging her. After the female koi releases her eggs they sink to the bottom of the pond and stay there. A sticky outer shell around the egg helps keep it in place so it does not float around. Although the female can produce many spawns, many of the fry do not survive due to being eaten by others. On average if the egg survives around 4–7 days the fry will be hatched from the egg.
Like most fish, koi reproduce through spawning in which a female lays a vast number of eggs and one or more males fertilize them. Nurturing the resulting offspring is a tricky and tedious job, usually done only by professionals. Although a koi breeder may carefully select the parents they wish based on their desired characteristics, the resulting fry nonetheless exhibit a wide range of color and quality.
Koi produce thousands of offspring from a single spawning. However, unlike cattle, purebred dogs, or more relevantly, goldfish, the large majority of these offspring, even from the best champion-grade koi, are not acceptable as nishikigoi or may even be genetically defective. These unacceptable offspring are culled at various stages of development based on the breeder's expert eye and closely guarded trade techniques. Culled fry are usually destroyed or used as feeder fish, while older culls, within their first year between 3 and 6 inches long, are often sold as lower-grade, pond-quality koi.
The semi-randomized result of the koi's reproductive process has both advantages and disadvantages for the breeder. While it requires diligent oversight to narrow down the favorable result that the breeder wants, it also makes possible the development of new varieties of koi within relatively few generations.

In the wild

Koi have been accidentally or deliberately released into the wild in every continent except Antarctica. They quickly revert to the natural coloration of an Amur carp within a few generations. In many areas, they are considered an invasive species and a pest. In the state of Queensland in Australia, they are considered noxious fish.
Koi greatly increase the turbidity of the water because they are constantly stirring up the substrate. This makes waterways unattractive, reduces the abundance of aquatic plants, and can render the water unsuitable for swimming or drinking, even by livestock. In some countries, koi have caused so much damage to waterways that vast amounts of money and effort have been spent trying to eradicate them, largely unsuccessfully.
In many areas of North America, koi are introduced into the artificial "water hazards" and ponds on golf courses to keep water-borne insect larvae under control through predation.

Koi in culture

The koi has important symbolic meaning in traditional Chinese culture and Japanese culture, relevant accounts can be seen in various ancient Chinese poetry and literature since Jin dynasty; while in Japan, it's closely associated with the country's national identity, often as a symbol of luck, prosperity, and good fortune.
In Sri Lanka, interior courtyards most often have one or several fish ponds dedicated to koi. Sri Lanka is the sixth largest cultivator of ornamental fish in the world after Singapore, Hong Kong, Malaysia, Thailand and the Philippines.