The ricefishes are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

(Adrianichthyidae) of small

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

that are found in fresh and

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

waters from

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

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 out into the

Malay Archipelago The Malay Archipelago (Indonesian/Malay: , tgl, Kapuluang Malay) is the archipelago between mainland Indochina and Australia. It has also been called the " Malay world," "Nusantara", "East Indies", Indo-Australian Archipelago, Spices Archipe ...

, most notably

Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...

(where the

Lake Poso Lake Poso ( id, Danau Poso) is a lake in Central Sulawesi, Indonesia, and the third-deepest lake in Indonesia. The town of Pendolo is situated at the southern end of the lake, the town of Tentena is located at the northern end, while a numbe ...

and Lore Lindu species are known as buntingi). The common name ricefish derives from the fact that some species are found in

rice paddies A paddy field is a flooded field of arable land used for growing semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cultures of the Yangtze River basin in southern China, associated with pre-Aust ...

. This family consists of about 37 species in two

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

(some recognize a third, '' Xenopoecilus''). Several species are rare and

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

, and some 2–4 may already be

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

Description

Most of these species are quite small, making them of interest for aquaria. ''Adrianichthys'' reach lengths of depending on the exact species involved, while the largest ''Oryzias'' reaches up to . Most ''Oryzias'' species are less than a half this length, with the smallest being up to only long. They have a number of distinctive features, including an unusual structure to the jaw, and the presence of an additional bone in the tail. The

Japanese rice fish The Japanese rice fish (''Oryzias latipes''), also known as the medaka, is a member of genus ''Oryzias'' ( ricefish), the only genus in the subfamily Oryziinae. This small (up to about ) native of East Asia is a denizen of rice paddies, marshes, ...

(''O. latipes''), also known as the medaka, is a popular

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

used in research in

developmental biology Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and di ...

. This species has traveled into

space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...

, where they have the distinction of being the first vertebrate to mate and produce healthy young in space. Genetic study of the family suggests that it originally evolved on Sulawesi and spread from there to the Asian mainland; the supposed genus '' Xenopoecilus'' are apparently unrelated, morphologically divergent species of ''Oryzias''.Takehana ''et al.'', 2005

Taxonomy

The ricefish were formerly classified within the order

Cyprinodontiformes Cyprinodontiformes is an order of ray-finned fish, comprising mostly small, freshwater fish. Many popular aquarium fish, such as killifish and live-bearers, are included. They are closely related to the Atheriniformes and are occasionally inc ...

but in the 1980s workers showed that they were a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

grouping, mainly based on the characters on the bones of the gill arches and the

hyoid The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical vertebra. ...

apparatus, within the

Beloniformes Beloniformes is an order composed of six families (and about 264 species) of freshwater and marine ray-finned fish: * Adrianichthyidae (ricefish and medakas) * Belonidae (needlefish) * Exocoetidae (flyingfishes) * Hemiramphidae (halfbeaks) ...

as the

Adrianichthyidae, this family making up one of the three suborders of the Beloniformes, the Adrianichthyoidei. Since then some workers have placed them in the Cyprinodontiformes but more recently molecular studies have supported their placement in the Beloniformes.

History

Ricefish are believed to have been kept as aquarium fishes since the 17th century. The Japanese ricefish was one of the first species to be kept and it has been bred into a golden color, from their original white coloring.

Reproduction

As with most fish, ricefish typically spawn their eggs, which are fertilised externally. However, some species, including the Japanese ricefish, are known to fertilise the eggs internally, carrying them inside the body as the embryo develops. The female then lays the eggs just before they hatch. Several other species carry their eggs attached to the body between their

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

References

Sources

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External links

FishBase info for Adrianichthyidae

{{Taxonbar, from=Q1045684 Adrianichthyidae Beloniformes Taxa named by Max Carl Wilhelm Weber