“Shaku” Size

“Shaku” is the traditional Japanese unit of measurement that equals 30.3cm (11.92inch): 1 Shaku=10 Sun.
“Naki Shaku(Naki-Jaku)” refers to a fish size that is considerd “so close””just short”: Naki means “tear dropping” in Japanese.

Why “Shaku”?

Because both Iwana and Yamame inhabit small mountain streams in Japan, it is rare for them to exceed “Shaku” in length, which is particularly unusual for Yamame, which typically only live for 2 to 3 years.
​It is not known when the word “Shaku” first came to be used to describe fish size, but it has now become a very symbolic word for a trophy-sized fish in Japan's mountain streams.