The Japanese white crucian carp, also known as Japanese carp, white crucian carp, or gengoro-buna (''Carassius cuvieri''), is a species of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

fish in the

carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...

family (family

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest verte ...

). It is found in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and, as an introduced species, in several other countries in Asia. This fish is closely related to the commonly known goldfish.

Description

This is a medium fish, growing up to 50 cm, with a broad head and a blunt snout. The lips are fleshy, and lacking barbels. The body is deep and laterally compressed, with a distinctly humped back. The scales are large and cycloid in shape, with a complete

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

. Serration is present on the last ray of the dorsal and

anal fins Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

, and the caudal fin is forked.

Taxonomy

The Japanese white crucian carp was formerly considered a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

wild goldfish The common goldfish is a breed of goldfish with no other differences from its living ancestor, other than its color and shape. Goldfish are a form of domesticated wild carp and are a close relative of koi. Most varieties of fancy goldfish we ...

, and was classified as ''C. auratus cuvieri''. It has now been elevated to species rank, however some authors are in disagreement. Genetic studies using

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

indicate that this species diverged from the ancestral form approximately one million years ago, during the early Pleistocene. The original wild species unique to Lake Biwa is called . Fossil pharyngeal teeth that appear to belong to ancestral form of Japanese white crucian carp have been found in the upper part of the Katata Formation, derived from sediment layers of the former Paleo-lake Katata, on the southwest shore of Lake Biwa.

Distribution and habitat

Historically, the Japanese white crucian carp was endemic to Lake Biwa, as well as the connected Yodo River system, in Japan. However, it has been introduced to Taiwan and Korea. In South Korea initial introductions were the result of stocking by government agencies. Subsequently, the species has also been spread through the Buddhist practice of "life releasing", in which animals destined for slaughter are instead released into the wild. Possession of this species without a permit is prohibited in the state of Vermont. It is a freshwater fish, preferring still or slow moving waters, and occurs at depths up to 20 meters. Typical habitats include lakes, canals, and backwaters.

Feeding, diet, and related information

An omnivorous species, Japanese white crucian carp feed on a variety foods, including

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

, macrophytes, and invertebrates, such as insects and crustaceans. During the

larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The l ...

stage, zooplankton comprise the primary food source. Upon reaching 1.8 cm the young fish form schools and move offshore to feed on phytoplankton. Phytoplankton remains the primary food source through adulthood. This is reflected in the unique structure of their pharyngeal teeth, which are specialized to feed on phytoplankton.

Reproduction

Spawning occurs from April to June, and takes place in areas of aquatic vegetation, including

reed bed A reedbed or reed bed is a natural habitat found in floodplains, waterlogged depressions and estuaries. Reedbeds are part of a succession from young reeds colonising open water or wet ground through a gradation of increasingly dry ground. As ...

s. Some individuals will migrate into connected satellite water bodies in order to spawn. Larvae and juveniles tend to remain close to spawning areas.

Importance to humans

Japanese white crucian carp, as well as other crucian carp species, are the target of an established local fishing industry on Lake Biwa. It is being used as a substitute for the depleted stock of '' nigoro-buna'' in the preparation of the intense-smelling fermented local dish ''

funazushi The history of began with paddy fields, where fish was fermented with vinegar, salt and rice, after which the rice was discarded. The earliest form of the dish, today referred to as , was created in Japan around the Yayoi period (early Neolithic ...

'' due to the ''nigoro-buna'''s falling numbers. A larger cultivated variant, with a taller body depth known as , was developed from the original species, cultured in the Osaka area and now released in many areas of Japan for sport fishing. It is enjoyed for catch-and-release. It is a major carp species in

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

aquaculture, where it is raised for food. This species has been identified as an

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

of ''

Clinostomum complanatum Clinostomum is a genus of Trematoda, trematodes in the Order (biology), order Diplostomida. Species Species include: *''Clinostomum abdoni'' Tubangui & Garcia, 1939 *''Clinostomum africanum'' Stossich, 1906 *''Clinostomum album'' Rosser, Alberson ...

'', a parasitic

fluke Fluke may refer to: Biology * Fluke (fish), a species of marine flatfish * Fluke (tail), the lobes of the tail of a cetacean, such as dolphins or whales, ichthyosaurs, mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ...

capable of infecting humans.

Conservation status

The wild species in Lake Biwa is listed as an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

in the Japanese

Red Data Book The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

.Search system of Japanese Red Data
Factors in its decline include water pollution, invasive species, and

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

References

Japanese white crucian carp The Japanese white crucian carp, also known as Japanese carp, white crucian carp, or gengoro-buna (''Carassius cuvieri''), is a species of freshwater fish in the carp family (family Cyprinidae). It is found in Japan and, as an introduced species, ...

Endemic fauna of Japan Freshwater fish of Japan Freshwater fish of Taiwan

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