The ricefishes are a family (Adrianichthyidae) of small ray-finned fish that are found in fresh and brackish waters from India to

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 nu ...

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 ( 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 ''Xenopoecilus'' is a genus of small fish in the family Adrianichthyidae. All members of the genus are threatened and endemic to lakes in Sulawesi, Indonesia. Pollution and the introduction of other fish into the lakes are the main reasons for t ...

''). Several species are rare and threatened, 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, marshe ...

(''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, 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 ''

'' 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: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Cyprinodontiformes 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 apparatus, within the Beloniformes as the family Adrianichthyidae, this family making up one of the three

suborder Order ( la, ordo) 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 ...

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 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

* *

External links

FishBase info for Adrianichthyidae

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