Marusen-Kobayashi Koi Farm (丸仙小林養鯉場)

For nearly five decades, Marusen-Kobayashi Koi Farm has been devoted to the art of breeding Nishikigoi in the heart of Uonuma, Niigata Prefecture—the birthplace of Japanese koi. Established by the Kobayashi family and now led by Naoto Kobayashi (小林直人), the farm continues a proud legacy built on patience, precision, and deep respect for nature.

Founded over 48 years ago, Marusen-Kobayashi has steadily grown into one of Niigata’s respected koi breeders. The farm’s location in Uonuma offers ideal conditions: pure mountain spring water, crisp winters, and lush summers that encourage slow, healthy growth and rich colour development.

Generations of knowledge and selective breeding ensure that each koi produced here carries both aesthetic excellence and structural strength—qualities that define Japanese koi worldwide.

• Over 30,000 m² of rearing grounds spread across the Uonuma countryside
• Carefully managed mud ponds that encourage natural growth and vibrant colouration
• Modern indoor systems for tosai (young koi) development and overwintering
• A balance of tradition and innovation—natural rearing complemented by expert care

Marusen-Kobayashi is especially renowned for:

• Shiro Utsuri – elegant black-and-white koi with bold contrasts and refined sumi placement
• Showa Sanshoku (Showa) – dynamic tri-coloured koi combining red (hi), white (shiro), and black (sumi) in dramatic balance
• Kawari (varieties/unique koi) – striking one-of-a-kind koi that reflect the breeder’s creative spirit

Each koi is hand-selected through multiple cullings, with the breeder’s eye ensuring only the strongest and most beautiful remain for future development.

The quality of Marusen-Kobayashi koi has been recognised both in Japan and abroad. Their koi have achieved awards at prestigious shows, including the International Juvenile Nishikigoi Show, where the farm’s dedication to quality has been celebrated.

Beyond competitions, Marusen-Kobayashi is committed to the koi community:

• International sales and export through trusted dealers
• Active engagement online via Facebook and Instagram, where enthusiasts can follow the farm’s seasonal activities, tosai selections, and pond harvests
• A warm welcome to visiting hobbyists, who often remark on the farm’s balance of professional breeding and family atmosphere