Emerald Fin Medaka

Emerald Fin 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 sheen carried on the fins is the main attraction, so this variety also rewards side viewing. Outdoors, shade half the container with a reed screen or similar to avoid summer overheating.

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

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 variety tends toward long fins, which are easily damaged, so take care with obstructions in the container. 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.

About Emerald Fin Medaka

Emerald Fin Medaka is an improved scale-glow lineage variety whose fins carry intense light, with a tendency toward long, flowing fins. Bred in 2020 by Masaharu Tarumi, it reaches about 4 cm and suits keepers with some experience.

7 things to know before welcoming a Emerald Fin Medaka

1. 1Fin Glow Varies by Fish

   The netted body glow that defines this variety differs in intensity and spread from one fish to another, even within the same bloodline. The shimmer often becomes more pronounced as the fish matures, so it's worth watching how each individual develops rather than judging solely by its appearance at pickup.

2. 2Long Fins Need Care

   This variety is said to tend toward long, flowing fins. Because trailing fins are more prone to damage from strong water flow or sharp decor, it helps to set up a tank environment that's gentle on delicate fins.

3. 3Best for Experienced Keepers

   This variety is generally rated as suited to keepers with some prior experience. Maintaining the fin glow and long-fin traits that define the bloodline benefits from a working knowledge of water quality management and regular observation.

4. 4Adult Size Around 4 cm

   Adults reach a standard length of up to about 4 cm. That manageable size gives keepers flexibility, whether housing them in an indoor aquarium, a water lily pot, or an outdoor biotope.

5. 5Bred in 2020

   The Emerald Fin Medaka was developed in 2020 by breeder Masaharu Tarumi as an improved variety from a scale-glow lineage. Knowing that it was bred specifically to emphasize fin-borne light rather than body color helps frame what to look for when choosing and enjoying individual fish.

6. 6Fin-Friendly Tankmates

   Medaka themselves are peaceful fish that get along calmly with others, but individuals with long, trailing fins can be at risk of nipping from more aggressive tankmates. When mixing species, it's safer to avoid known fin-nippers and to keep this variety with its own kind.

7. 7Acclimate Slowly at Pickup

   Sudden shifts in water quality or temperature right after bringing the fish home can be stressful, so a gradual acclimation process is essential. Keep a close eye on its condition, including the fins, right after transport, and provide a calm environment until it settles in.

Frequently asked questions about Emerald Fin Medaka

Q.What kind of variety is the Emerald Fin Medaka?

A.It's an improved medaka from a scale-glow lineage, known for concentrating its light in the fins rather than the body. Bred in 2020 by Masaharu Tarumi, this line is said to tend toward long, flowing fins.

Q.Can beginners keep the Emerald Fin Medaka?

A.This variety is generally considered suited to keepers with some experience. Since maintaining its signature fin glow and long fins benefits from water-quality know-how, it's best approached after building basic medaka-keeping skills.

Q.Do all individuals grow long fins?

A.While the variety is said to tend toward long, flowing fins, how much each individual's fins grow varies. Not every fish will develop fins of the same length.

Q.How large do adults get?

A.Adults reach a standard length of up to about 4 cm. That's a manageable size for medaka, suiting everything from indoor aquariums to outdoor biotopes.

Q.Can it be kept in an outdoor biotope?

A.Yes, outdoor keeping is possible. To appreciate its body glow and fin coloring clearly, it helps to use a container that's easy to view from above and to give it moderate sunlight, while watching for sudden temperature swings.

Useful tools for Emerald Fin Medaka care

Learn more about Emerald Fin Medaka in the encyclopedia

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