Oryzias asinua PARENTI, HADIATY, LUMBANTOBING & HERDER, 2013

Asinua Ricefish

Etymology

Oryzias: from the Greek ὄρυζα (oryza), meaning ‘rice’, in reference to the tendency of some members of the genus to inhabit rice paddy fields.

asinua: named for the type locality in Asinua District, Sulawesi Tenggara (Southeast Sulawesi), Indonesia.

Classification

Order: Beloniformes Family: Adrianichthyidae

Distribution

Known only from the Sungai (river) Asinua in Asinua District, Sulawesi Tenggara (Southeast Sulawesi), Indonesia.

Habitat

When the type series was collected the Sungai Asinua contained clear, slow to fast-moving water with a temperature of 26 °C.

The substrate was composed of mud, sand and gravel with patches of emergent grasses, and O. asinua was collected along the shores and in small marginal pools in the adjacent floodplain.

Sympatric species included an unidentified native Nomorhamphus sp., a possibly native Clarias sp., and the exotics ‘Puntius‘ binotatus, Trichopodus trichopterus, and Oreochromis sp.

Maximum Standard Length

The largest specimen known to date measured 25.4 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 45 ∗ 30 cm or more should prove sufficient.

Maintenance

Most Oryzias spp. are best maintained in a heavily planted set-up, ideally with a dark substrate, patches of dense vegetation, and some open areas.

Additional décor can consist of twisted roots and pieces of bogwood, while surface vegetation is also appreciated by the fish.

When maintained under such conditions they’re more likely to display their best colours, plus planted aquaria also offer fry a more favourable chance of survival alongside the adults.

Sexual Dimorphism

Adult males are more colourful, possess longer dorsal/anal fins and have a slimmer body shape than females.

The genital papilla in males forms a short, slightly conical tube, while in females it is bilobed.

NotesTop ↑

This species does not yet appear to have been collected for the aquarium hobby.

It’s included in the O. woworae species group (Parenti et al., 2013) within the genus of which members possess orange to deep red pigmentation on the caudal-fin margins, ventral margin of the caudal peduncle and at least the posterior portion of the base of the anal-fin, plus a bluish sheen on the body that is most pronounced in live adult males.

The group also contains O. wolasi which like O. asinua differs from O. woworae by possessing elongate medial dorsal-fin rays in males extending to the posterior extent of the first principal caudal-fin ray plus an orange-coloured olfactory epithelium on each nasal organ in at least females in life.

It can be further distinguished by the fact that both sexes have orange-coloured olfactory epithelia, versus only present in females O. wolasi and absent in O. woworae, plus it is relatively slender with body depth 21–25% SL, mean 22.9%, versus 23–32%, mean 25.3% in O. wolasi and 22–30%, mean 26% in O. woworae.

Members of the family Adrianichthyidae are often referred to collectively as ‘ricefishes’ and were traditionally considered to be members of the family Cyprinodontiformes and thus closely-related to toothcarps.

This misconception is sometimes still upheld despite the fact that Rosen and Parenti reclassified them within the cyprinodontiform sister group Beloniformes as long ago as 1981.

The best-known member of the family is the medaka or Japanese ricefish, Oryzias latipes, which has been widely used as a model organism in genomic and experimental biology for well over a century and was the first vertebrate animal to mate in space during the mid-1990s.

There are currently just two genera included in the family, Oryzias and Adrianichthys, with the historically-recognised groupings Xenopoecilus and Horaichthys having been synonymised with Oryzias by Parenti (2008).

Of the three species previously included in the paraphyletic Xenopoecilius, X. oophorus and X. poptae were moved into Adrianichthys with the third, X. sarasinorum currently recognised as Oryzias sarasinorum.

In addition the formerly monotypic Indian species Horaichthys setnai is currently classified as O. setnai.

References

1. Parenti, L. R., R. K. Hadiaty, D. Lumbantobing, and F. Herder, 2013 - Copeia 2013(3): 403-414
   Two New Ricefishes of the Genus Oryzias (Atherinomorpha: Beloniformes: Adrianichthyidae) Augment the Endemic Freshwater Fish Fauna of Southeastern Sulawesi, Indonesia.
2. Herder, F. and S. Chapuis, 2010 - The Raffles Bulletin of Zoology 58(2): 269-280
   Oryzias hadiatyae, a new species of ricefish (Atherinomorpha: Belonifornes: Adrianichthyidae) endemic to Lake Masapi, Central Sulawesi, Indonesia.
3. Parenti, L. R., 2008 - Zoological Journal of the Linnean Society 154(3): 494-610
   A phylogenetic analysis and taxonomic revision of ricefishes, Oryzias and relatives (Beloniformes, Adrianichthyidae).
4. Parenti, L. R. and R. K. Hadiaty, 2010 - Copeia 2010 (2): 268-273
   A new, remarkably colorful, small ricefish of the genus Oryzias (Beloniformes, Adrianichthyidae) from Sulawesi, Indonesia.
5. Roberts, T. R., 1998 - Ichthyological Research 45(3): 213-224
   Systematic observations on tropical Asian medakas or ricefishes of the genus Oryzias, with descriptions of four new species.
6. Takehana, Y., K. Naruse K and M. Sakaizumi, 2005 - Molecular Phylogenetics and Evolution 36(2): 417-428
   Molecular phylogeny of the medaka fishes genus Oryzias (Beloniformes: Adrianichthyidae) based on nuclear and mitochondrial DNA sequences.