How difficult is it to keep Longfin Medaka?

Intermediate. This is an intermediate-level species. Some prior experience and knowledge of environmental management are recommended.

What is the ideal temperature for Longfin Medaka?

The ideal temperature for Longfin Medaka is 18〜28℃. Avoid sudden temperature changes and maintain a stable environment.

What is the lifespan of Longfin Medaka?

The average lifespan of Longfin Medaka is 2-3 years. With proper care and nutrition, they can live a long and healthy life.

How large does Longfin Medaka get?

Longfin Medaka typically reaches Up to about 4cm SL as an adult. Size may vary depending on care conditions and individual genetics.

What should I feed Longfin Medaka?

Longfin Medaka feeds on: Prepared medaka food, green water. Aim for a balanced diet with appropriate feeding frequency.

What is the typical price for Longfin Medaka?

The price of Longfin Medaka varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.

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Longfin Medaka

Intermediate

Oryzias latipes

An improved medaka whose dorsal and anal fin rays extend across the whole fin. Only the rays elongate and the extended part carries no fin membrane, which distinguishes it from hirenaga, where every fin extends.

Difficulty

Intermediate

Temperature

18〜28℃

Lifespan

2-3 years

Size

Up to about 4cm SL

Diet

Prepared medaka food, green water

About

Longfin is not a single variety but a fin-variation trait class in which the dorsal and anal fins extend; the Medaka Web Encyclopedia lists it as the 36th of the recognised traits. The rays of the dorsal and anal fins elongate across the whole fin, and in lines carrying external luminescence the sheen tends to appear on the extended part as well. The similar trait is hirenaga, but the two differ in both extent and manner. Hirenaga elongates every fin and the fin membrane with it, whereas longfin elongates only the dorsal and anal fins and only their rays, so the extended part has no membrane. The difference is easiest to judge by viewing the fish from the side. It combines with any body colour or body type, so fish are named by adding Longfin to an existing variety name, as in blue miyuki longfin or rinkou longfin.

Source: Wikipedia (CC BY-SA 4.0)

Lifespan of the Longfin Medaka

The Longfin Medaka lives 2-3 years.

Size of the Longfin Medaka

The Longfin Medaka grows to Up to about 4cm SL.

Temperature & humidity for the Longfin Medaka

The ideal temperature for the Longfin Medaka is 18〜28℃.

Basic Info

Origin

Japan (a trait class of improved medaka; the Medaka Web Encyclopedia records no breeder or year)

Lifespan

2-3 years

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: Longfin, fin-variation trait 36/44

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

Longfin (dorsal and anal fin-ray extension)

Sources: Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025) / Medaka Web Encyclopedia: Medaka Traits / Medaka Web Encyclopedia: Longfin, fin-variation trait 36/44 / Medaka Web Encyclopedia: Hirenaga (Matsui hirenaga), fin-variation trait 35/44

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

Taxonomy & Authority

Accepted name: Oryzias latipes (Temminck & Schlegel, 1846)

Authority databases: FishBase · GBIF · Medaka Web Encyclopedia: Longfin, fin-variation trait 36/44 · 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.

Longfin Medaka Listings

Find listings for this species

🩺 Common diseases

Care Guide

Lighting

Because it is the dorsal and anal fins that extend, the fin shape is easiest to judge from the side. In lines that also carry external luminescence the sheen reaches the extended part, so the fish reads differently from above and from the side. Outdoors, summer sun raises water temperature sharply, so shade half the container with something such as a reed screen.

Diet & Nutrition

Commercial prepared medaka food is the staple, given in an amount finished within a few minutes. Leftovers decay and foul the water, so adjust the quantity. Green water rich in phytoplankton suits fry rearing.

Water Temperature & Quality

Slightly acidic to slightly alkaline water is considered ideal, and the water drifts toward acidic as keeping continues. Around one water change per week is the guideline, and because sudden shifts in temperature or pH cause stress, acclimatise new fish by floating the bag. FishBase records the wild water chemistry of this species as pH 7.0-8.0 and hardness 9-19 dH.

Tank Mates & Compatibility

Elongated fins are easily damaged by obstructions or crowding, so keep the container uncluttered and the stocking light. A peaceful schooling fish, normally kept as a group of the same variety. One litre of water per fish is the guideline against overcrowding; overstocking causes poor growth, reduced breeding, oxygen shortage and water fouling.

Breeding

Outdoors the spawning season runs from about April to October, once water reaches 18C or above with 12-13 hours of daylight. For year-round indoor breeding, 25-28C water and over 13 hours of lighting are the guideline. Eggs hatch at a cumulative 250 degree-days, about 10 days at 25C.

Health & Notes

The extended rays carry no membrane and are thin, so they damage easily; keep sharp-edged obstacles out of the container. The trait is often confused with hirenaga, but hirenaga elongates every fin together with its membrane while longfin elongates only the rays of the dorsal and anal fins. Outdoors the fish become inactive and overwinter near the bottom as water cools, resuming activity in spring once daytime water exceeds 10C. A 0.3-0.5% salt bath is used for ailing fish, with water raised to no more than about 28C.

Longfin Medaka

About

Lifespan of the Longfin Medaka

Size of the Longfin Medaka

Temperature & humidity for the Longfin Medaka

Basic Info

Care Specifications

Morphs (Varieties)

References & Sources

Taxonomy & Authority

Regulations & Conservation Status

Longfin Medaka Listings

Related Articles

🩺 Common diseases

For Breeders

Longfin Medaka

About

Lifespan of the Longfin Medaka

Size of the Longfin Medaka

Temperature & humidity for the Longfin Medaka

Basic Info

Care Specifications

Morphs (Varieties)

References & Sources

Taxonomy & Authority

Regulations & Conservation Status

Longfin Medaka Listings

Related Articles

🩺 Common diseases

Diet