Isa Koi Farm

Isa Koi Farm

Founded in 1971 by Hajime Isa and now run by his son Mitsunori Isa, Isa Koi Farm is located in Ojiya City, Niigata Prefecture—the heartland of Nishikigoi. Covering approximately 70,000 m² and with 31 mud ponds, the farm has established itself as one of Japan’s most respected breeders, admired worldwide for its uncompromising quality and bold approach to Showa development.

The farm’s reputation rests on its iconic Isa Showa. These koi are instantly recognisable for their powerful, well-balanced bodies, their dramatic contrast of jet-black sumi against deep red and snow-white skin, and their ability to grow to impressive sizes while maintaining beauty. Over the years, Isa Showa have consistently won major prizes, including the coveted Kokugyo Award at the All Japan Nishikigoi Show—cementing their place among the finest koi in the world.

While Showa remain the farm’s signature variety, Isa also breeds Kohaku and Taisho Sanke, ensuring a well-rounded Gosanke offering. However, it is the Showa that truly embody the farm’s breeding philosophy. Mitsunori Isa places particular emphasis on the role of environment and soil quality in koi development, believing that even fry from the same parents can achieve completely different results depending on the mud in which they are raised. This deep understanding of nature’s role in koi growth has been key to the farm’s success.