Tōtenkō Medaka (東天光メダカ) – A Rising Sun in Your Aquarium

Tōtenkō Medaka (東天光メダカ) is a radiant strain of improved Japanese rice fish known for its rich, deep red coloration and symmetrical Hikari (光) body form. A descendant of the famous Yōkihi (楊貴妃) line, this variety reflects the tranquil beauty of a sunrise—with every swim capturing light like dawn on water.

🌅 Name Origin

The name “Tōtenkō” (東天光) means “Eastern Sky Light,” evoking the glowing horizon at daybreak. It was originally going to be named “Tōtenkōu” (東天紅), meaning “Eastern Crimson,” but breeder Yukio Ōba (大場 幸雄) chose the character for “light (光)” instead of “crimson (紅)” to emphasize the Hikari body form—a signature trait of this medaka.

🧬 Origin & Development

• First Appearance: Circa 2004–2005
• Original Breeder: Yukio Ōba (大場 幸雄)
• Affiliation: Medaka no Yakata
• Lineage: Developed from Hikari-bodied offspring discovered during the stabilization of the Yōkihi strain

Ōba meticulously selected and bred only the red-colored medaka that exhibited symmetrical Hikari body traits, ultimately resulting in the stable Tōtenkō line we know today.

🎨 Physical Characteristics

• Color: Bright crimson body color, reminiscent of a morning sun
• Body Type: Hikari—marked by symmetrical dorsal and anal fins, and a diamond-shaped caudal fin
• Top-View Appeal: The guanine layer along the back reflects light beautifully, giving the fish a glowing dorsal appearance from above

🔁 Fixation & Breeding Tips

The Tōtenkō Medaka is considered to have a high fixation rate and is beginner-friendly. However, as with many Hikari types, breeders should watch for spinal irregularities or asymmetrical tail fins and select for well-balanced body structure along with vibrant coloration.

• Focus on selecting individuals with straight spines and even fin symmetry
• Bright, consistent red pigmentation should be prioritized for long-term line integrity
• Occasional non-Hikari forms may appear and should be excluded from breeding

✨ Conclusion

The Tōtenkō Medaka is more than just an ornamental strain—it’s a reflection of tradition, balance, and refined breeding. With its historical roots, luminous red color, and symmetrical body type, it offers a timeless beauty suitable for both collectors and dedicated breeders alike.

※ This article was compiled from breeder references and original material published at Medakazukan.