205 Years of JPD: From Goldfish Merchants to Champion Koi Nutrition

When you scoop a handful of JPD pellets into your pond, you are feeding your koi the end product of one of the longest unbroken lineages in ornamental fish — a Yoshida family that has been raising, ranking, and caring for koi and goldfish in Japan since 1819. That date is not marketing varnish; it is printed on the bag and stamped into the company seal.

Most premium koi foods are made by feed companies. JPD’s story is different, and the difference is the whole point: it grew out of a fish family first, and a fish-medicine company second. Two hundred years of breeding taught the Yoshidas what a healthy koi looks like. A half-century of veterinary science taught them how to keep it that way. The food is where those two things meet.

1819: “Yoshida of Goldfish”

The family seal reads Kingyo no Yoshida — “Yoshida of Goldfish” — founded in the second year of the Bunsei era, 1819. In late-Edo Japan, ornamental goldfish keeping was a genuine craze, and the Yoshidas built their name as breeders and dealers. By the late 1800s the family was publishing ranked goldfish lists — the kind of ranchu ranking records that survive in the family archive from 1899.

The Yoshida Fish Farm

By the 1940s the family operation had become the Yoshida Fish Farm — rows of earthen ponds and grow-out houses raising both goldfish and nishikigoi at scale. This is where the modern company takes root. The man who would carry the brand into the modern era, Ryuichi Yoshida, grew up inside it, appearing in the family album as a small child in the 1950s and, by 1967, as a boy working part-time at the farm. He is still the face of JPD today, known to koi keepers worldwide for the “Koi Clinic” he runs.

1964–1969: food, then medicine, then the world

The company’s first fish food, “Swimmy,” launched in 1964. Four years later, in 1968, the Yoshida operation began exporting living koi and goldfish around the world, with beautifully produced English catalogs — Living Jewels, Brocaded Carp, Exotic Goldfish — that introduced Japanese nishikigoi to a global audience.

Then came the pivot that still defines JPD. In 1969 the family founded Japan Pet Design Co., Ltd. The very next product line was not a food at all. It was medicine: the Green F family of fish-disease treatments. JPD set out to cure sick fish before it set out to feed healthy ones.

JPD is the only major koi food made by the company that also makes the medicine — roughly 90% of Japan’s fish-treatment market.

Becoming Japan’s fish doctor

Over the following decades JPD became the dominant name in Japanese aquatic-animal health, by its own account holding around 90% of the domestic fish-medicine market, with treatments produced in a GMP (Good Manufacturing Practice) pharmaceutical facility — the same standard used for human and veterinary drugs. That medical DNA is the thing competitors cannot copy. When JPD designs a koi food around immunity, gut health, or recovery, it is drawing on a pharmacology lab, not a marketing brief.

2009: putting the science in the pellet

The clearest proof of the medicine-meets-food idea came in 2009, when JPD — working with researchers at Mie University and Japan’s National Fisheries University — developed a nishikigoi food built around egg-yolk antibodies (IgY) targeting koi herpesvirus (KHV). The concept, now well documented in peer-reviewed aquaculture science, is elegant: immunize hens against a fish virus, harvest the protective antibodies that concentrate in their egg yolks, and deliver them to koi orally through feed — passive immunity in a pellet.

That research culture still drives the lineup Mystic Koi carries today, from Swimmy (1964) through the Medicarp health-care foods to the modern champion-grade formulas — Shori, Fujizakura, Shogun and AkaFuji. JPD’s health-care foods have helped produce World Grand Champion koi at the All Japan show, which is why hobbyists call it “the food behind champions.”

A 205-year timeline

Sources: JPD 205th Anniversary (Japan Pet Design) commemorative publication, 2026 — primary source for company history, dates and milestones. Peer-reviewed research on egg-yolk immunoglobulin (IgY) against cyprinid herpesvirus in carp (Aquaculture; Journal of Virology, 2021).