The World's First F1 Farmed Fish "Yume-Aji" Takes On the Wild "Seki-Aji"—A Tokyo University of Marine Science-Born Startup Ships 8,000 Fish to Toyosu and Michelin Restaurants, a New Model for Sustainable Fisheries

Sakana Dream Inc. (Tateyama, Chiba), a startup originating from Tokyo University of Marine Science and Technology,the world's first F1 cross-bred farmed fish "Yume-Aji", began full-scale shipment in March to April 2026. Born from crossing the kaiwari, called the "phantom fish," with golden horse mackerel from Minamiboso, Chiba, Yume-Aji features rich fat and umami likened to "the toro of white-fleshed fish." On April 18 to 19, a taste-comparison sushi set pairing it with the natural pinnacle "Seki-Aji" was sold at Nakajima Suisan, among other events, hinting at the dawn of a new era in which farmed fish stand shoulder to shoulder with wild fish.

What is "Yume-Aji"—the aquaculture innovation born of the world's first F1 cross

Kaiwari × golden horse mackerel interspecies cross

Yume-Aji is an F1 (first-generation cross) of the high-end jack-family fish "kaiwari" and the "golden horse mackerel" landed at Minamiboso, Chiba. The kaiwari has extremely low catch volumes and is known as a "phantom fish," characterized by strong umami. The golden horse mackerel, on the other hand, is known for its good fat. By crossing these two species,umami × fat, a new fish possessing both was born.

An Eco-Conscious "Single-Generation" Design

What stands out is that Yume Aji is designed asan infertile, single-generationfish. Even if one escapes the farm, it cannot reproduce, so there is no risk of contaminating the gene pool of wild fish.For Agriture, which championsa sustainable future for food

, this is a noteworthy, eco-conscious approach to variety development.

Why "Aquaculture × Selective Breeding" Matters Now

The Wild Catch Is One-Third of Its Peak

Japan's wild fish catch has fallen sharply from its peak (about 12.82 million tons in 1984) and now stands at roughly one-third of that. To make up for this structural decline in supply, more advanced aquaculture is essential, but conventional farming has long carried the image of a "degraded version of wild."

Shunichi Hosoya, head of Sakana Dream, sets "making the world's most delicious fish" as the company's mission and aims for farmed fish that surpass wild in quality. Although Japan is home to over 4,000 species of fish, only a handful have undergone selective breeding in aquaculture. It is a challenge to bring the cycle taken for granted in agriculture—"selective breeding → higher quality → branding"—into fisheries.

The Same Idea as Agricultural Selective BreedingIn agriculture, crossing different varieties has produced brand varieties like "Koshihikari" and "Shine Muscat." Yume Aji is a case that applies this idea to fisheries, pointing toa new direction for innovationFood OEMin Japan's food industry. Just as our approach to raising the value of off-grade produce through dried vegetables, creating "quality that surpasses wild" through aquaculture offers a new option for the raw-material procurement of

as well.

"Seki-Aji vs. Yume Aji" Tasting Debuts April 18

On April 18–19, the high-end fresh-fish retailer Nakajima Suisan will sell a "Yume Aji vs. Seki-Aji" tasting sushi set. It is the first-ever attempt in which a farmed F1 fish squarely challenges "Seki-Aji," the pinnacle of wild brands.

Source

• Its distribution channels are varied too: shipments to Toyosu Market and Nagoya Central Wholesale Market, supply to Michelin-listed restaurants, and handling at "Uo Ichiban," a seafood theme park run by the YouTuber "Kimagure Cook." It is also offered for a limited time as a furusato-nozei return gift from Tateyama, Chiba, securing a direct touchpoint with consumers.
• Sakana Dream Inc. press release, "World's First F1 Farmed Fish Yume Aji Enters Full Shipment" (PR TIMES)
• Nihon Nogyo Shimbun, "Sakana Dream's Yume Aji × Seki-Aji Tasting Event" (April 14, 2026)