These tubs are mixed with Sanke and Showa
The Showa is the last of the Big Three varieties collectively known as Go Sanke, and historically it's by far the youngest. It wasn't until 1927, in Niigata, when Jukichi Hoshino crossed a Ki Utsuriwith a Kohaku that the first Showa came to be. These early fish displayed very poor, yellowish hi and indifferent sumi. Then, in 1965, Tomiji Kobayashi improved the strain by crossing a female Showa with a male Sanke and a male Kohaku. The resulting fry wore deep scarlet hi, glossy black sumi, and snow-white skin akin to those we appreciate today.