| Ricefishes | |
|---|---|
| Medaka, Oryzias latipes | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Beloniformes |
| Family: | Adrianichthyidae |
| Genera | |
|
Adrianichthys |
|
The ricefishes are a family (Adrianichthyidae) of small ray-finned fish that are found in fresh and brackish waters from India to Japan and out into the Indo-Australian Archipelago, most notably Sulawesi. The common name of the group derives from the fact that many species are found in Japanese rice paddies.[1] About 27 species, some extremely rare and endangered, and some 2-4 may already be extinct.
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Most of these species are quite small, making them of interest for aquaria. The largest species, the Buntingi, is 20 centimetres (7.9 in) in length, but most are less than a fifth this length, with the smallest being only 1.7 centimetres (0.67 in) 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.[1]
As with most fish, ricefish typically spawn their eggs, which are fertilised externally. However, some species, including the medaka, 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 fins.[1]
The medaka, Oryzias latipes, is a popular model organism used in research in developmental biology.
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.[2]
As currently defined, the ricefishes include 28 species grouped into four genera[3]:
Family Adrianichthyidae