Japanese Ricefish (Oryzias latipes)

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Japanese Ricefish

Oryzias latipes-5481.jpg
Japanese Ricefish

Oryzias latipes

57 Litres (15 US G.)

3-4 cm (1.2-1.6")


7.0 - 8.0

18 -24 °C (64.4-75.2°F)

9-19 °d

1:2 M:F

Pellet Foods
Flake Foods
Live Foods
Other (See article)

4-8 years



This animal is available captive bred

Additional names

Japanese Ricefish, Japanese Rice Fish, Medaka, Japanese Killfish

Additional scientific names

Poecilia latipes, Aplocheilus latipes, Oryzias latipes latipes


In the male, six anterior rays of the anal fin are separated from the rest of the fin and modified into a gonopodium. Of the six rays the third, fourth and fifth ones are profoundly modified. In the female right pelvic fin is usually absent and her fins are shorter and more rounded in shape.

Tank compatibility[edit]

These are very small fish and for that reason are best kept in species tanks. They will easily become dinner to larger fish. Best kept in groups of 6 or more.


Should accept a variety of foods including pellet and flake as well as live/frozen foods such as brine shrimp and bloodworm.

Feeding regime[edit]

Feed once or twice a day.

Environment specifics[edit]

While this fish may be sold for freshwater, it really does best in a brackish environment. Prefers a spacious tank with plenty of open swimming space and little current.


A peaceful loosely shoaling fish.


The Japanese Ricefish is a very small elongated and slender fish with a pointed snout and upturned mouth. The anal and dorsal fin are towards the back of the fish and caudal fin is more square in shape compared to equally small fish such as Endlers Livebearers. The eyes are blue. There are several colour variants. Wild types are pale cream in colour, almost translucent. There are also yellow variant and they area also known to be genetically modified, see below.

Species Notes[edit]

These fish have been seen genetically modified in other colours using the same method as Glofish. They will look a lot like the Glofish but without the Zebra Danio's stripes. This fish will have the same restrictions as it is a GM product as the Glofish does. They may be referred to as "Fluorescent Ricefish".
This fish is used in many medical and scientific research projects, it's even been to space! It was the first vertebrate to mate in space, the fish laid eggs and had a successful brood of fry in orbit. They were on board the space shuttle Columbia in 1994.[1]



In a store tank:


External links[edit]