How difficult is it to keep Tainaikou (Inner-Glow) Medaka?

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

What is the ideal temperature for Tainaikou (Inner-Glow) Medaka?

The ideal temperature for Tainaikou (Inner-Glow) Medaka is 18〜28℃. Avoid sudden temperature changes and maintain a stable environment.

What is the lifespan of Tainaikou (Inner-Glow) Medaka?

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

How large does Tainaikou (Inner-Glow) Medaka get?

Tainaikou (Inner-Glow) 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 Tainaikou (Inner-Glow) Medaka?

Tainaikou (Inner-Glow) Medaka feeds on: Prepared medaka food, green water. Aim for a balanced diet with appropriate feeding frequency.

What is the typical price for Tainaikou (Inner-Glow) Medaka?

The price of Tainaikou (Inner-Glow) Medaka varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.

AI-generated image

Tainaikou (Inner-Glow) Medaka

Intermediate

Oryzias latipes

An improved medaka carrying a trait that produces a bluish-white glow inside the body. The glowing layer forms a horizontal plate, so it can only be seen from above, which distinguishes it from external luminescence on the back. It appears mainly on white and blue body colours.

Difficulty

Intermediate

Temperature

18〜28℃

Lifespan

2-3 years

Size

Up to about 4cm SL

Diet

Prepared medaka food, green water

About

Tainaikou is a trait that traces back to a medaka exhibited by Tomoyuki Tomatsu at the 2nd Japan Medaka Show in 2008, in which a bluish-white glow appears inside the body. The Japan Medaka Association classification manual places it among the iridophore traits, and the Medaka Web Encyclopedia lists it as trait 24. The colour resembles the afterglow of a fluorescent lamp just switched off, and because the glowing layer forms a horizontal plate it can be seen only from above and is almost invisible from the side. When first created the glow started near the dorsal fin and reached only about half the body length, but in 2014 fish glowing as far as the pectoral fins were produced, and the best of these are called super tainaikou. As the trait is derived from the miyuki variety, the glow appears mainly on white and blue body colours. The colour of the glow varies between individuals, and bluish-white, green (ryokkou tainaikou), orange, multi-colour and blue are recorded as sub-categories. Certified new varieties of the Japan Medaka Association also include white lame miyuki tainaikou (No.8, 2013, Toshihiro Wada) and miyuki tainaikou nishiki (No.12, 2015, Toshihiro Wada).

Source: Wikipedia (CC BY-SA 4.0)

Lifespan of the Tainaikou (Inner-Glow) Medaka

The Tainaikou (Inner-Glow) Medaka lives 2-3 years.

Size of the Tainaikou (Inner-Glow) Medaka

The Tainaikou (Inner-Glow) Medaka grows to Up to about 4cm SL.

Temperature & humidity for the Tainaikou (Inner-Glow) Medaka

The ideal temperature for the Tainaikou (Inner-Glow) Medaka is 18〜28℃.

Basic Info

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: Tainaikou (inner glow)

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

Inner glow (bluish-white)Inner glow (green, ryokkou tainaikou)Inner glow (orange)Inner glow (multi-colour)Inner glow (blue)

Sources: Japan Medaka Association: Variety Classification Manual, 5th ed. (Sep 2025) / Medaka Web Encyclopedia: Medaka Traits / Medaka Web Encyclopedia: Tainaikou (inner glow)

A curated selection of notable morphs. Inheritance modes are a breeding-planning guide; actual appearance varies with combos.