Rinkou Medaka

Rinkou 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 net-like sheen appears on the back, so the variety is best viewed from above, and a dark container makes the outline of each scale stand out. The Medaka Web Encyclopedia recommends outdoor keeping and notes that summer sun raises water temperature sharply, suggesting shade such as a reed screen over half the container.

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 fin sheen is strong and some fish develop longfin, so keep the container uncluttered to protect the extended fins. The net-like sheen depends on the condition of the scales, so avoid handling that strips them. 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 Rinkou Medaka

Rinkou Medaka is an improved variety with net-like body glow from individually lit scales, featuring yellow-blue semi-transparent scales and glowing fins for intermediate keepers.

7 things to know before welcoming a Rinkou Medaka

1. 1Body glow varies between individuals

   Because each scale catches light individually, the mesh-like glow pattern varies from fish to fish, even among siblings from the same parents. Watching how the pattern develops as the fish matures is part of the enjoyment.

2. 2Some individuals develop long fins

   Rinkou Medaka carries strong fin glow, and some individuals show elongated long-fin traits in the tail and fins. Fish with extended fins are more sensitive to water flow, so gentle current settings are worth considering.

3. 3Best suited to intermediate keepers

   Maintaining the distinctive coloration and body glow of this improved variety calls for a working knowledge of water quality and light exposure, making it a better fit for keepers with some prior medaka experience.

4. 4Adults reach about 4cm

   Adult Rinkou Medaka reach a standard length of up to about 4cm, a manageable size for compact tanks or biotopes. Still, a cramped container can affect coloration and pattern development, so it's worth providing ample swimming space.

5. 5Glow effect stands out in groups

   The net-like body glow of Rinkou Medaka looks especially three-dimensional when several fish swim together, giving the whole group a shimmering effect. Keeping multiple fish together, rather than a single individual, brings out this variety's signature appeal.

6. 6Avoid sudden changes in water conditions

   As with medaka in general, sudden shifts in water quality or temperature can cause stress and health problems. Take time with drip acclimation when introducing new fish, and perform regular partial water changes to help keep them healthy.

7. 7Prepare the setup before bringing them home

   It's important to have the tank or biotope cycled and water conditions stabilized before bringing Rinkou Medaka home. Improved varieties can be sensitive to environmental changes, so make sure the setup and acclimation plan are ready in advance.

Frequently asked questions about Rinkou Medaka

Q.Is Rinkou Medaka subject to CITES?

A.Rinkou Medaka is not subject to CITES. It can be kept and acquired like any standard medaka variety without special international trade restrictions.

Q.How does the net-like glow pattern change as the fish grows?

A.The net-like glow pattern tends to become more defined as the scales develop with growth. Since individual variation is significant, watching the change from juvenile to adult is part of the enjoyment.

Q.Can beginners keep this variety?

A.Rinkou Medaka is considered suited to intermediate keepers, so some prior medaka-keeping experience is reassuring. Since it requires attention to water quality and light conditions, first-time keepers may want to consider starting with a more beginner-friendly variety.

Q.Do some individuals not develop long fins?

A.Yes, while Rinkou Medaka carries strong fin glow overall, whether an individual develops long fins varies. Many grow up with standard fin length, so not every fish will show the long-fin trait.

Q.Can it be kept together with other medaka varieties?

A.Medaka varieties can generally be kept together, but if you want to fully appreciate the body glow and coloration of Rinkou Medaka, keeping them separately with others of the same variety makes the pattern easier to enjoy. If mixing varieties, manage water quality and feeding carefully.

Useful tools for Rinkou Medaka care

Learn more about Rinkou Medaka in the encyclopedia

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