Visiting Koi Hobbyist 2025　Tetsuya Koyano (Ibaraki Prefecture)

With the completion of his house pond, the ‘second chapter’ begins, dreaming big in a huge pond.

One more passionate hobbyist has pushed their interest to the next level, striving for even greater achievements. Tetsuya Koyano, who runs a manufacturing company in Chikusei City, Ibaraki Prefecture, has built two impressive ponds on his company’s expansive grounds—a 70-ton pond and a 35-ton pond. Although these were created primarily as his personal koi ponds, he named the facility “Koyano Koi Farm” upon completion and even launched a website. While enjoyment remains his top priority and it is not a commercial venture, his dream is ambitious: to become the best in Japan. I met him and some of his koi-keeping friends who had helped with the pond’s design and construction, and I learned about his meticulous approach to pond building and the direction he is aiming for.

Built ponds for every koi size—
crafted by an expert and completely satisfying.

The visit took place in late July on an extremely hot day, and the temperature inside the greenhouse was expected to be very high.
The surrounding area is a peaceful rural landscape. Construction of the koi ponds on a section of the spacious property began in March 2024. By late May, the ponds were completed, and after covering the pond with plastic for greenhouse, the ponds were ready for use just before summer.
The two ponds, far beyond the scale of a typical hobbyist, hold 70 and 35 tons respectively, each greenhoused in a separate structure. The scale perfectly justifies the name “Koyano Koi Farm.” While keeping his personal enjoyment of koi as the top priority, Tetsuya says he also plans to consider sales in the future, depending on demand.

“Inevitably, maintenance costs are high, so I hope at least to cover the electricity and feed expenses (laughs),” Tetsuya said. “Right now, I have about 100 koi, and the cost of their food alone is quite substantial.”
When planning the ponds, he consulted several contractors, but either their estimates didn’t fit his budget or they lacked experience in building koi ponds, making it difficult to get the project started.

At that time, during a sales event at Odakan’s Sano Fujioka branch, Kyo Sekine happened to visit the store and was introduced as a pond-building specialist. A koi enthusiast who runs a construction company, he had even built his own 200-ton pond, so things progressed quickly from there.
“Kyo has built nearly seventy koi ponds so far, so I felt completely confident leaving it to him. I hardly made any requests myself, yet this pond was completed. Once a pond is built, you can’t really go back and fix it. There’s no substitute for proven experience,” Tetsuya explained.