Koi — KHV years · 159

Colour mutants were kept in Yamakoshi rice-terrace ponds in the early 1800s. The 1914 Tokyo Taisho exhibition took them national. The ZNA-centred championship that still sets kohaku, sanke and showa as the Gosanke core classes. After the 1960s export boom, Israeli and US growers scaled food-and-ornamental carp. Butterfly fins are largely a non-Niigata aesthetic.

Koi herpesvirus outbreaks from the late 1990s killed whole collections. Quarantine and certified-free stock became the new entry ticket. Common carp are invasive in many rivers and lakes. A show pond is secure; a flood overflow is not a garden anymore. Giverny water lilies host carp in the public mind. The nishikigoi fancy is Japanese; the Impressionist pond is a later cross-reading.

The ornamental lineage is mass-bred and not Red-Listed. High resilience here means secure stock, not ecological innocence. Koi is one of 24 types in this animals atlas. The pages treat it as a full system -- history, anatomy, operating principles, culture, icons, future pressure and market shape -- not a ranking of a best species.