Sailfin Medaka
The Sailfin Medaka is a selectively bred medaka variety known for its distinctive split dorsal fin, which appears divided into two separate sections. This trait arises from a lack of membrane or rays in part of the dorsal fin, and tends to show up in Hikari and Hikari Datenma body types. In a 2022 revision of variety naming conventions, this trait was renamed "Samurai." The elegant, flowing silhouette of its fin is the main appeal, and it can be combined with other medaka varieties to create striking new expressions. Considered suited to intermediate keepers, it makes a rewarding next step for those who have mastered the basics of medaka care.
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Sailfin Medaka key facts
- Care level
- Intermediate
- Lifespan
- 2-3 years
- Size
- Up to about 4cm SL
- Temperature
- 18〜28℃
- Diet
- Prepared medaka food, green water
- Lighting
- The split dorsal is clearest from above, so a container viewed from the top suits the variety. The Medaka Web Encyclopedia recommends outdoor keeping and suggests shading half the container in summer.
- 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
- Fin shape varies between fish, and selection favours those with a cleanly formed pair of dorsals. Because the look resembles merah and choki, identify the trait by checking which fins divide and how many result.
About Sailfin Medaka
Sailfin Medaka is a selectively bred variety with a split dorsal fin, common in Hikari and Hikari Datenma types. Renamed "Samurai" in 2022, this intermediate-level fish grows to a standard length of about 4cm.
7 things to know before welcoming a Sailfin Medaka
1Signature Split Dorsal Fin
The Sailfin Medaka's defining trait is its dorsal fin, which appears split into two sections due to a lack of membrane or rays. This trait tends to show up in Hikari and Hikari Datenma body types. Because the way the fin splits varies between individuals, each fish has its own unique look.
2Renamed "Samurai" in 2022
A 2022 revision to variety naming standards renamed this trait "Samurai." Since both "Sailfin" and "Samurai" are still used by shops and breeders, it's worth knowing both names when looking for this variety.
3Best Suited to Intermediate Keepers
The Sailfin Medaka is considered an intermediate-level variety. Beyond basic medaka care, keeping an eye on its distinctive fin shape calls for a bit more observation, so it's best approached once you're comfortable with medaka husbandry.
4Typical Adult Size
Adults reach a standard length of up to about 4cm. There's no extreme size difference from standard medaka, so the same tank or outdoor container sizing works fine.
5Watching the Fin for Health
Because the dorsal fin is split, it can actually be easier to spot changes in fin condition than with a standard medaka. Check regularly for fraying edges or color changes so you can catch issues early.
6Understanding the Genetic Trait
The Sailfin (Samurai) trait tends to appear alongside Hikari and Hikari Datenma body types. If you're considering breeding, keep in mind that how the trait expresses can shift depending on which varieties you cross.
7Preparing Your Setup Before Bringing One Home
Before bringing one home, set up your tank or outdoor container and get the water conditions ready. Since this variety is prized for its fin shape, also think about tankmate compatibility to keep those fins looking their best.
Frequently asked questions about Sailfin Medaka
- Q.Are Sailfin Medaka and Samurai Medaka different varieties?
- A.No, they refer to the same trait. A 2022 revision to naming standards renamed "Sailfin" to "Samurai," so both names are still in use today.
- Q.Why does the dorsal fin look split into two?
- A.This trait results from a lack of membrane or rays in part of the dorsal fin. It tends to appear in Hikari and Hikari Datenma body types.
- Q.Is this variety suitable for beginners?
- A.It's considered an intermediate-level variety. It's easier to manage and observe once you already have some experience keeping medaka.
- Q.How large does it grow?
- A.It reaches a standard length of up to about 4cm, similar in size to standard medaka.
- Q.Are there any legal restrictions on keeping or importing it?
- A.This variety is not subject to CITES.
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