Aquarist Atlas
Ricefish · Mainland South & Southeast Asian ricefish · Oryzias

Oryzias uwai

Roberts, 1998

2 cited sourcesName checked against Eschmeyer’s Catalog of Fishes, update of

IUCNDATA DEFICIENT · 2011
DDnot on the EX–LC scale
CARESNOT LISTED
Type localityRangoon, Myanmarper Catalog of Fishes
Scientific size0.5 in1.6 cm standard length
Depth—not recorded
DietNot documented for this species; ricefishes in general take small invertebrates and algae at or near the surface
BreedingNot documented for this species
Sexual dimorphismNot documentedNot documented for this species
PhotographsSee photosGoogle Images →

Oryzias uwai is a very small ricefish from Myanmar, described by Roberts in 1998 from the Rangoon area. FishBase gives a maximum of 0.5 in SL. It is poorly known and has no hobby record.

Taxonomy & naming

Roberts described the species in 1998 in a revision of the mainland Southeast Asian Oryzias. The name honours Uwa, whose work on ricefish chromosomes and systematics included describing O. mekongensis.

Morphology

A tiny ricefish; FishBase gives a maximum of 0.5 in SL.

Habitat

Lowland waters around Yangon, Myanmar. FishBase lists the Irrawaddy, Rangoon and Sittang basins and describes a freshwater, benthopelagic fish.

Feeding

Diet is not documented.

Mating

Courtship has not been described.

Breeding

Breeding has not been documented.

In the aquarium

Not known in the aquarium trade.

Conservation

The IUCN Red List assessed Oryzias uwai as Data Deficient in 2011, meaning there is too little information to judge its extinction risk.

Common questions

Oryzias uwai: how big does it get?
Up to 0.5 in standard length (SL).
Oryzias uwai: where does it come from?
It is recorded from Myanmar.

On a list: Nano fish

Related species compared · Oryzias

SpeciesAdult sizeTemperaturepHHardnessIUCN
Oryzias uwaithis species0.5 in SL———DD
Songkhram medakaOryzias songkhramensis0.5 in SL———DD
Dwarf medakaOryzias minutillus1 in TL72–77 °FpH 7.5–8.5—LC
Oryzias haugiangensis1 in SL———DD
Oryzias hubbsi1 in SL———NT
Oryzias pectoralis1 in SL———DD
Oryzias chenglongensis1 in SL———NE
Oryzias moramoensis1 in SL———NE
Oryzias asinua1 in SL———EN
Daisy's ricefishOryzias woworae1 in SL—pH 6–7—EN
Soeroto's ricefishOryzias soerotoi1 in SL———CR
Oryzias wolasi1 in SL75–79 °F——DD

Recorded ranges from each species’ own page; hardness is the tolerance its sources give, not a measurement of the water it lives in. See all 40 Oryzias species →

Sources

  1. FishBase — Oryzias uwai Roberts, 1998
  2. Eschmeyer's Catalog of Fishes (California Academy of Sciences) — Oryzias uwai
  3. Parenti, L.R. (2008) A phylogenetic analysis and taxonomic revision of ricefishes, Oryzias and relatives (Beloniformes, Adrianichthyidae). Zoological Journal of the Linnean Society 154: 494-610

Naming authority: Oryzias uwai in Eschmeyer’s Catalog of Fishes ↗

Last reviewed 2026-10-05.

How to cite

Aquarist Atlas (2026). Oryzias uwai. Aquarist Atlas.https://www.aquaristatlas.com/ricefish/oryzias-uwai/

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Where it has been recorded

9 georeferenced records (GBIF). Each point is a field observation or museum specimen — pan and zoom to explore where this species turns up. The coordinates come straight from GBIF and are often rounded or tied to the nearest town or river landing, so a dot can sit just beside the actual water rather than in it.

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