Big-Eye Medaka
IntermediateOryzias latipes
A trait in which the pupil appears blue, or the black-bodied line that carries it. Guanine on the cornea makes it look blue; body colour and scales are unaffected.
Blue eye is one of the eye traits in the Japan Medaka Association classification manual: the pupil appears blue. According to the Kairyo Medaka Web Zukan, guanine on the cornea produces the blue, which ranges from deep to whitish. Like albino or panda it changes eye colour, but no effect on body colour or scales has been confirmed. It was found and fixed in a black-bodied variety, introduced by the Web Zukan as 'black blue-eye medaka' without background adaptation. In outcrosses, about 17% of F1 offspring showed blue-eye-like eye changes, with fewer showing it clearly in both eyes. More colours may follow. Since 'blue eye' is also a trait name, check the full variety name including body colour when buying.
Source: Wikipedia (CC BY-SA 4.0)
The Blue-Eye Medaka grows to About 3-4 cm (wild medaka reach up to 4 cm SL: FishBase).
Origin
Japan (ornamental cultivar)
Lifespan
Few reliable data
Size
About 3-4 cm (wild medaka reach up to 4 cm SL: FishBase)
Temperature
5〜30℃
Omnivore (floating prepared foods, live foods such as daphnia)
Edited & verified by: BreederDirect editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Accepted name: Oryzias latipes (Temminck & Schlegel, 1846)
Synonyms: Aplocheilus latipes (Temminck & Schlegel, 1846), Poecilia latipes Temminck & Schlegel, 1846
Authority databases: GBIF · GBIF · 日本メダカ協会 品種分類マニュアル
Nomenclature follows global taxonomic authority databases.
Ornamental medaka are cultivars of Oryzias latipes. Not listed in the CITES Appendices (checked on Species+) and not regulated under Japan's Invasive Alien Species Act. Japan's wild medaka (Oryzias latipes and O. sakaizumii) are listed as Vulnerable on the Ministry of the Environment Red List and differ genetically by region. Releasing ornamental medaka into rivers, ponds or rice paddies causes genetic pollution through hybridisation with wild fish, so never release them.
Sources: Species+ (CITES) / Ministry of the Environment: list of invasive alien species / Wikipedia (Japanese): Medaka – conservation and genetic pollution
Regulations may change. Always verify the latest information with the relevant authorities.
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Eye colour is easiest to see up close from the side; the black body has no background adaptation, so it stays dark in glass tanks.
In outcrosses only about 17% of F1 showed the trait; pair fish with clear blue in both eyes.
Peaceful and fine with other medaka of similar size. To keep the variety's traits, do not let it breed with other varieties in the same container.
Give floating food that is eaten within 3-5 minutes: at least twice a day in summer, once a day in spring and autumn, and little or none outdoors in winter.
Never release ornamental medaka into rivers, ponds or paddies; hybridisation causes genetic pollution of wild medaka.
Beginner. This is a beginner-friendly species. No special equipment or experience is required, and it can be kept successfully with basic care setup.
Blue-Eye Medaka typically reaches About 3-4 cm (wild medaka reach up to 4 cm SL: FishBase) as an adult. Size may vary depending on care conditions and individual genetics.
Blue-Eye Medaka feeds on: Omnivore (floating prepared foods, live foods such as daphnia). Aim for a balanced diet with appropriate feeding frequency.
The price of Blue-Eye Medaka varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.
Last updated: September 23, 2026
