血ち合あい

noun

dark red flesh of fish; blood-rich meat near the spine

Refers specifically to the dark, blood-rich meat found along the spine of fish like tuna and bonito. Often contrasted with the lighter, fatty flesh.

• マグロの血ち合あいは鉄てつ分ぶんが豊ほう富ふだ。

  The dark red flesh of tuna is rich in iron.

• 血ち合あいの部ぶ分ぶんは独どく特とくの風ふう味みがある。

  The blood-rich meat has a distinctive flavor.