Medaka Encyclopedia

Japan Blue Medaka – ジャパンブルーメダカ

Japan Blue Medaka (ジャパンブルーメダカ) Overview The Japan Blue Medaka is a striking ornamental variety known for its deep, dark body tone contrasted by a brilliant blue dorsal iridescence. Developed through precise selective breeding, this medaka showcases the vibrant expression of external light (体外光) in a unique way that has captured the attention of enthusiasts. Physical Characteristics Body Color: Dark-toned body with a smooth black or brown base External Light (体外光): Intense blue shine along the back — a signature trait of this line Visual Contrast: The pairing of black and blue creates a clean, high-impact look Breeding Information Year of Development: 2020 Breeder: Hiroki Kawato Lineage: Carefully developed from medaka with yellow-black bodies and blue dorsal iridescence. Successive generations were selectively bred to stabilize both color and shine. This led to the birth of the fixed, high-contrast strain now known as Japan Blue. Conclusion The Japan Blue Medaka combines simplicity with sophistication. Its bold contrast between dark body and bright blue dorsal light makes it a standout choice for both breeders and collectors. It is a shining example of what dedicated, thoughtful medaka breeding can achieve.