Marmorated medaka (Oryzias marmoratus): how big does it get?

Up to 4.1 cm standard length (SL).

Marmorated medaka (Oryzias marmoratus): what water temperature does it need?

The atlas records 22–25 °C for this species.

Ricefish · Sulawesi ricefish · Oryzias

Oryzias marmoratus

(Aurich, 1935)

Marmorated medaka, Marbled ricefish

Full synonymy (1)

Aplocheilus marmoratus Aurich 1935 · original combination

Source: Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Van der Laan, eds.), California Academy of Sciences.

2 cited sourcesName checked against Eschmeyer’s Catalog of Fishes, update of 21 Sep 2026

IUCNNEAR THREATENED

EXEWCRENVUNTLC

CARESNOT LISTED

EWCRENVUNTnot on the priority list

Type localitySmall rivulets flowing into lake at Lingkoburanga, about 6 km south of Timampu, Lake Towoeti [Towuti], Sulawesi, Indonesiaper Catalog of Fishes

Scientific size1.5 in4.1 cm standard length

Temperature72–77 °F22–25 °C

pH7.5–8.5alkaline

Depth—not recorded

DietSmall invertebrates and algae

BreedingNot documented for this species

Sexual dimorphismNot documentedNot documented for this species

PhotographsSee photosGoogle Images →

Oryzias marmoratus is a marbled ricefish from Lake Towuti and associated waters in Sulawesi, described by Aurich in 1935. FishBase gives a maximum of 1.5 in SL, and the IUCN lists it as Near Threatened.

Taxonomy & naming

Aurich described the species in 1935 in a different genus, and it is now placed in Oryzias; the authority is therefore in parentheses. The type locality is a rivulet entering Lake Towuti at Lingkoburanga, south of Timampu.

Morphology

A small ricefish, with a mottled or marbled pattern that gives the name. FishBase gives a maximum of 1.5 in SL.

Habitat

Lake Towuti and streams entering it in Sulawesi, as well as nearby waters of the Malili system. FishBase gives a pH range of 7.5 to 8.5 and a temperature range of 22 to 25 C.

Feeding

Takes small invertebrates and algae.

Mating

Courtship has not been described in detail.

Breeding

FishBase reports that females carry egg clusters under the ventral fin. Clutch size and incubation time have not been published.

In the aquarium

Occasionally kept by Sulawesi enthusiasts. A planted tank with a lid, water in the pH 7.5 to 8.5 range and small live and frozen foods suits it.

Conservation

The IUCN Red List classes Oryzias marmoratus as Near Threatened, meaning it is close to qualifying for a threatened category. The Malili lakes face introduced fishes and catchment change.

Common questions

Marmorated medaka (Oryzias marmoratus): how big does it get?: Up to 1.5 in standard length (SL).
Marmorated medaka (Oryzias marmoratus): what water temperature does it need?: The atlas records 72–77 °F for this species.
Marmorated medaka (Oryzias marmoratus): what water chemistry suits it?: pH 7.5–8.5.
Marmorated medaka (Oryzias marmoratus): where does it come from?: It is recorded from Indonesia.

Related species compared · Oryzias

Species	Adult size	Temperature	pH	Hardness	IUCN
Marmorated medakaOryzias marmoratusthis species	1.5 in SL	72–77 °F	pH 7.5–8.5	—	NT
Oryzias loxolepis	1.5 in SL	—	—	—	NE
Towuti ricefishOryzias profundicola	2.5 in TL	72–77 °F	pH 7.5–8.5	—	NT
Matano medakaOryzias matanensis	2 in TL	72–77 °F	pH 7.5–8.5	—	NT
Hainan medakaOryzias curvinotus	1.5 in TL	—	—	—	DD
Masapi ricefishOryzias hadiatyae	1.5 in SL	—	—	—	VU
Japanese medakaOryzias latipes	1.5 in SL	64–75 °F	pH 7–8	161–339 ppm	LC
Luzon ricefishOryzias luzonensis	1.5 in TL	—	—	—	EN
Timor ricefishOryzias timorensis	1.5 in TL	—	—	—	CR
Celebes medakaOryzias celebensis	2 in TL	72–86 °F	pH 8–9	—	LC
Javanese ricefishOryzias javanicus	2 in TL	72–77 °F	pH 7.5–8.5	—	LC
Northern medakaOryzias sakaizumii	1.5 in SL	—	—	—	LC

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 →

Also from Lake Towuti

Sources

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

Last reviewed 2026-10-05.

How to cite

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

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Where it has been recorded

1 georeferenced record (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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