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Big-Eye Medaka
IntermediateOryzias latipes
An improved medaka in which the eye itself is unusually large. Unlike the telescope-eye trait, where the eyes protrude, here the eye is simply big in proportion to the body. The trait was found and fixed in 2009 by the Niitani family. Seventeen varieties carrying it are registered in the Medaka Web Encyclopedia.
Difficulty
Intermediate
Temperature
18〜28℃
Lifespan
2-3 years
Size
Up to about 4cm SL
Diet
Prepared medaka food, green water
About
Big-eye is the trait in which the diameter of the eye becomes unusually large. The Medaka Web Encyclopedia lists it as eye trait 19, explained in line with the Japan Medaka Association classification manual. According to the reference work Medaka Hinshu Zukan it was discovered and fixed by Hirotaka and Tsutomu Niitani of Hiroshima Prefecture and announced in 2009. Unlike the telescope-eye trait the eye does not project from the body; it is simply larger in proportion, which is easiest to see beside a normal-eyed fish. The encyclopedia records 17 varieties carrying the trait. Certified new varieties of the Japan Medaka Association include big-eye seiga (No.25, 2016, Hirotaka Niitani), blue big-eye miyuki hirenaga (No.27, 2017, Hirotaka Niitani) and black big-eye (No.28, 2017, Hirotaka Niitani), along with blue big-eye bubble-eye (No.9, 2015, Tsutomu Niitani), which combines it with the bubble-eye trait.
Source: Wikipedia (CC BY-SA 4.0)
Lifespan of the Big-Eye Medaka
The Big-Eye Medaka lives 2-3 years.
Size of the Big-Eye Medaka
The Big-Eye Medaka grows to Up to about 4cm SL.
Temperature & humidity for the Big-Eye Medaka
The ideal temperature for the Big-Eye Medaka is 18〜28℃.
Basic Info
Origin
Japan (a trait discovered and fixed in 2009 by Hirotaka and Tsutomu Niitani of Hiroshima Prefecture)
Lifespan
Care Specifications
- pH
- 7–8
- Hardness (GH)
- 9–19 dGH
- Water Temp.
- 18–28℃
PeacefulGroupBreeding: Moderate
Sources: Medaka Web Encyclopedia: Complete Medaka Care Guide / FishBase Oryzias latipes / Medaka Web Encyclopedia: Big eye
Morphs (Varieties)
The Japan Medaka Association's classification manual sorts varieties by traits that can be seen rather than by genotype, and does not set out how individual traits are inherited. Traits the manual explicitly says can be passed on and produced by selective, multi-generation breeding are listed as line-bred; the rest are grouped under Other.
Other
Big eyeBig eye with bubble eyeBig eye with telescope eye
Sources: Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025) / Medaka Web Encyclopedia: Medaka Traits / Medaka Web Encyclopedia: Big eye / Japan Medaka Association: List of Certified New Varieties
A curated selection of notable morphs. Inheritance modes are a breeding-planning guide; actual appearance varies with combos.
References & Sources
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.
Primary sources
- Wikipedia
- CITES Appendices (species not listed)
- FishBase (IUCN Red List: Least Concern, assessed 2018)
- Medaka Web Encyclopedia: Complete Medaka Care Guide
- Medaka Web Encyclopedia: Big eye
- Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025)
- Medaka Web Encyclopedia: Medaka Traits
- Japan Medaka Association: List of Certified New Varieties
- FishBase
Taxonomy & Authority
Accepted name: Oryzias latipes (Temminck & Schlegel, 1846)
Breeder: (2009)
Authority databases: FishBase · GBIF · Medaka Web Encyclopedia: Big eye · Japan Medaka Association: Variety Classification Manual
Nomenclature follows global taxonomic authority databases.
Regulations & Conservation Status
Not CITES-listedIUCN LC · Least Concern
Sources: CITES Appendices (species not listed) / FishBase (IUCN Red List: Least Concern, assessed 2018)
Regulations may change. Always verify the latest information with the relevant authorities.
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