A fillet knife is a long, narrow knife with a thin blade designed to separate fish flesh from the backbone, ribs and skin. Many fish fillet knives have a flexible blade that follows the contours of the fish and helps produce clean fillets with minimal waste. Blade length and flexibility should suit the species and size of fish being prepared.
After scaling and gutting the fish as required, make a controlled cut behind the gill plate and along the backbone. Keep the blade close to the bones and use smooth strokes to separate the flesh. Repeat on the other side, then remove pin bones and trim the fillet to the required specification. For skin-on portions, the knife can be used to separate the skin from the flesh with the blade held at a shallow angle.
A fillet knife is generally optimized for fish, with a narrow blade and often greater flexibility. A boning knife is designed to separate meat from bones in meat and poultry; it is often stiffer and may have a broader or more robust blade. Some knives can serve more than one purpose, but the correct tool improves control and yield.
Use a stable, non-slip cutting board and keep the knife sharp. Cut away from the supporting hand, keep fingers clear of the blade path and never try to catch a falling knife. Clean and sanitize the knife after use, especially when moving between raw fish species or other ingredients, and store it in a protected knife rack or sheath.
Chef’s tip: Choose blade flexibility based on the fish. A flexible blade can help with delicate fillets, while a stiffer blade may give better control on large, firm fish. Keep the edge sharp and let the knife do the work rather than forcing it through the flesh.
Related techniques: filleting a round fish and filleting a flatfish.
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