Visiting Hobbyist 2024　Koichi Shibuya (Yamagata Prefecture)

“I never imagined I’d become so engrossed in this…”
With more ponds, more koi, and more friends, my enjoyment keeps growing.

The garden, with its pond and impressive ancient pine, belongs to the Shibuya family, who have a history of over 300 years in this area, passed down through generations. Koichi Shibuya, who once had no specific hobbies, now finds Nishikigoi an indispensable part of his life, bringing him joy and enrichment. His Nishikigoi set-up is comprehensive, featuring a proper concrete pond, a picturesque garden pond, an indoor sheet pond for overwintering, mud ponds and aquariums—covering all aspects of koi care. I visited Koichi, who said with a smile, “I wake up and look at the koi, and in the evening, I watch them while enjoying a drink”. My visit was guided by his friend Kiichi Watanabe, who introduced Koichi in the December 2022 issue of this magazine. (Interview conducted in June 2023).

The Nishikigoi, once merely a decorative feature in the garden,

Captivated me after I built the pond.

The area, surrounded by expansive rice fields, has long been rich in water resources. Edible Magoi used to be kept in the backyard pond, fed by irrigation channels. The oldest photo of the backyard pond at the residence dates to 1929, but its history extends back over 200 years. The shape of the pond with a its small island in the centre has been unchanged since at least 1929, and the view from the living room is excellent. Due to its shallow depth, the old garden pond now serves as a retirement home for koi. Many in this pond have a long history with Koichi, and they quickly gather around whenever he stands nearby.
He conducts serious breeding in a concrete pond which holds around 12 tons of water that he built in the courtyard five years ago, and he is considering participating in koi shows as well. The overall shape is almost trapezoidal but with subtle curves on each side instead of straight lines to avoid the large garden stones while maximising water capacity. The pond can be admired from the living room and Western-style rooms, and on sunny days, it’s a luxurious experience to enjoy the view from the wooden deck.

He keeps about 25 three-year-old koi in the main pond. Taking the landscape into consideration, the two-chamber filtration system and the Wakishimizu 10 model (filter media) are quite a distance from the pond, positioned to be hidden by the building. Water is drawn in from a sedimentation tank near the pond. The filter media includes resin mesh and honeycomb, and oyster shells are used to improve the water quality. Although this area has abundant stream water to irrigate rice fields, it lacks groundwater, so tap water is used for koi breeding.
Given the fully outdoor arrangement and the region’s heavy snowfall, pond covering for overwintering extends from mid-November through the end of April.
“To withstand the weight of snow, sturdy square timbers are laid across the top of the pond, plywood panels are attached, and a sheet is placed over them. The circulation and aeration remain active so the water remains clean, even in spring, and weight or lustre is not lost,” Koichi said.
The beauty of the outdoor koi post-wintering is reportedly superior to the indoor pond mentioned later. The interview was conducted in early June. Despite it being shortly after the resumption of feeding, the koi’s colour and lustre were excellent, indicating a favourable environment.

A pond was created in the space originally used as a water reservoir for disaster prevention and as a snow disposal area during the winter. It was common sight to raise Magoi there as a source of protein during the winter.
“When I was a child, I hated collecting Magoi from the pond,” Koichi said. “But after my father passed away, I became interested in our garden. I thought having just black carp was dull, so I went to a koi shop to buy some coloured ones.“
His journey began at Uzenya, a koi shop in Tsuruoka City. At first, he struggled to keep the koi alive, often unintentionally causing their deaths by overfeeding. However, his priority was always the garden and the koi were seen as enhancing its beauty. He would replace them with inexpensive new koi if they died, as he wasn’t planning on serious breeding. Then, one day, the store owner, the late Sukeji Okamoto suggested that he make a pond.
“I thought it was quite ambitious,” Koichi laughed. “Since I started keeping koi for the garden, I wasn’t keen on spending too much money. I also needed to learn about filtration and that the water from the rice field channels was unsuitable. Still, I learned by seeing Kiichi’s pond and studying how he did it. Even after making the pond, there were various challenges like the cover collapsing under the weight of snow or the garden pond’s koi being eaten by animals, but Kiichi taught me each time something went wrong.”