The ricefishes are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

(Adrianichthyidae) of small

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

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, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

and out into the

Malay Archipelago The Malay Archipelago is the archipelago between Mainland Southeast Asia and Australia, and is also called Insulindia or the Indo-Australian Archipelago. The name was taken from the 19th-century European concept of a Malay race, later based ...

, most notably

Sulawesi Sulawesi ( ), also known as Celebes ( ), is an island in Indonesia. One of the four Greater Sunda Islands, and the List of islands by area, world's 11th-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Min ...

(where the Lake Poso and Lore Lindu species are known as buntingi). The common name ricefish derives from the fact that some species are found in rice paddies. This family consists of about 37 species in two

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

(some recognize a third, '' Xenopoecilus''). Several species are rare and threatened, and some 2–4 may already be

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. The fossil genus †'' Lithopoecilus'' de Beaufort, 1934 from the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

of Sulawesi may potentially represent a prehistoric member of the family, although it is only tentatively placed within it. It appears to be intermediate in size between ''Oryzias'' and ''Adrianichthys''.

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

model organism A model organism 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 workings of other organisms. Mo ...

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 a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

, 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 Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Cyprinodontiformes Cyprinodontiformes is an order (biology), order of Actinopterygii, ray-finned fish, comprising mostly small, freshwater fish. Many popular aquarium fish, such as killifish and Poeciliidae, live-bearers, are included. They are closely related t ...

but in the 1980s workers showed that they were a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

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 verte ...

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 (halfb ...

as the

Adrianichthyidae, this family making up one of the three

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

s 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 (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

References

Sources

* *

External links

FishBase info for Adrianichthyidae

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