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Mezen (Forward-Eye) Medaka
IntermediateOryzias latipes
An improved medaka whose eyes point diagonally forward, so that the fish appears to look straight back at you from the front. The angle varies between individuals, and close to 45 degrees is regarded as the best expression. It is an eye trait created in 2007 by Kazuyoshi Kinoshita.
Difficulty
Intermediate
Temperature
18〜28℃
Lifespan
2-3 years
Size
Up to about 4cm SL
Diet
Prepared medaka food, green water
About
Mezen is the trait in which the eyes point diagonally forward. The Medaka Web Encyclopedia lists it as eye trait 18, explained in line with the Japan Medaka Association classification manual. It was created in 2007 by Kazuyoshi Kinoshita of Tokushima Prefecture; seen from the front the fish seems to meet your gaze, and from above the forward angle of the eyes is obvious. The angle varies between individuals and changes the impression considerably, with close to 45 degrees considered the best state. Unlike telescope-eye or big-eye, which alter the size or projection of the eye, mezen changes only its direction. The encyclopedia records 36 varieties carrying the trait, including blue deme mezen (type No.0824) and youkihi transparent-scale mezen (type No.0732), which combine it with telescope eye or transparent scales. The Japan Medaka Association has also certified goromaru, a blue panda mezen, as new variety No.20 (2016, Ryoichi Nishizawa).
Source: Wikipedia (CC BY-SA 4.0)
Lifespan of the Mezen (Forward-Eye) Medaka
The Mezen (Forward-Eye) Medaka lives 2-3 years.
Size of the Mezen (Forward-Eye) Medaka
The Mezen (Forward-Eye) Medaka grows to Up to about 4cm SL.
Temperature & humidity for the Mezen (Forward-Eye) Medaka
The ideal temperature for the Mezen (Forward-Eye) Medaka is 18〜28℃.
Basic Info
Origin
Japan (a trait created in 2007 by Kazuyoshi Kinoshita of Tokushima Prefecture)
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: Mezen (forward-angled 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
Forward-angled eye (mezen)Telescope eye with mezenTransparent scale with mezen
Sources: Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025) / Medaka Web Encyclopedia: Medaka Traits / Medaka Web Encyclopedia: Mezen (forward-angled 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: Mezen (forward-angled eye)
- Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025)
- Medaka Web Encyclopedia: Medaka Traits
- Japan Medaka Association: List of Certified New Varieties
Taxonomy & Authority
Accepted name: Oryzias latipes (Temminck & Schlegel, 1846)
Breeder: 木下一好 (2007)
Authority databases: FishBase · GBIF · Medaka Web Encyclopedia: Mezen (forward-angled 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.
Mezen (Forward-Eye) Medaka Listings
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