Koi varieties, 8 classic types.

Koi are not a species you buy once - they are varieties you learn to read. The classics here run from the Gosanke trio (Kohaku, Taisho Sanke, Showa) that dominates every show bench, to single-color Ogons, blue-backed Asagi and Shusui, the red-capped Tancho, and longfin Butterfly koi that purists still argue about. All of them share one non-negotiable: a real pond. A well-kept koi passes 60 cm (2 feet) and lives for decades, so plan thousands of liters and serious filtration before you plan colors. The trade-off is cost and patience - good water costs more than good fish, and a young koi's pattern keeps shifting for years, sometimes into something better, often not. They suit pond owners who enjoy that long game; there is no aquarium version of it.