wiki- Eel Knife

• Definition:
  An Eel Knife is a specialized Japanese knife designed for filleting eel, particularly in traditional unagi and anago preparation. Unlike most kitchen knives, its structure varies significantly by region, reflecting distinct culinary techniques.
• Details:
  Eel knives are characterized by their rigid, thick blades and pointed or hooked tips, optimized for penetrating and opening the tough skin of eel. They are typically single-bevel and built with substantial spine thickness to withstand the force required when breaking through the eel’s resilient exterior. There are three main regional styles in Japan: the Kanto-style (Edo-saki), Kansai-style (Kyo-saki), and Nagoya-style, each differing in blade geometry and entry technique.
• Comparison:
  Unlike Yanagiba, Takohiki, or Fuguhiki knives, which emphasize long slicing motions for delicate sashimi, eel knives are designed primarily for controlled penetration and splitting rather than drawing cuts. They are also structurally heavier and more robust than standard sashimi knives, prioritizing strength and leverage over finesse.
• Practical Use:
  The eel knife is used to insert the tip near the head of the eel and split it open along the backbone in a single controlled motion. In the Kanto region, eel is opened from the back, while in Kansai it is opened from the belly. The knife’s rigid construction ensures stability and precision during this demanding process.
• Cultural Notes:
  Eel preparation is deeply embedded in Japanese culinary tradition, especially in dishes such as unagi kabayaki. The regional differences in eel knives reflect historical and cultural distinctions between Edo and Kyoto cuisine. Mastery of the eel knife represents technical discipline and respect for tradition, as proper filleting directly influences texture and flavor.

Related websites
A Collection of Other Types of Japanese Knives |KIREAJI