How to Choose the Right Fish Fillet Knife

The Art of Filleting Starts with the Right Tools; Four Experts Help You Choose

Give a filleting expert a lackluster, blunt knife, and watch as precision turns to butchery. A top-notch fishing fillet knife offers many advantages over a poorly designed or maintained one. Among them are:

• It protects your investment. After all, that's what describes the fish you catch; typically, you've made a substantial investment of your time and money to put them on ice. A good blade ensures clean, precise cuts, resulting in fillets with minimal loss of meat or irregularities.
• It protects you. Ironically, an angler is far more likely to wound himself when trying to fillet with a poorly made, dull knife than with a high-quality, razor-sharp fillet knife. The latter slices precisely with minimal effort, while the bad knife requires more guesswork and more forcing when making cuts.
• It saves you time and frustration. You’ll spend far more time trying to fillet a fish with a cheap, dull knife than with a serious blade. In other words, the right knife helps you do the job better and faster.

Making the case for using the right fishing fillet knife is one thing; figuring out if you have the right knife or not is a bit more involved. Good charter captains and guides are almost always pros when it comes to cleaning fish. For many, it’s an almost daily ritual, often done at a fish table — under their clients’ watchful gaze. Here’s the take of several experts, from long experience, on fillet knives.

Construction/Design

No aspect of a fillet knife is more critical than its blade construction. Most high-quality fish fillet knives today are stainless steel. Of course, not all stainless steel is created equal. Harder steel is generally better steel for fishing fillet knives, says Capt. Eric Newman of Journey South Outfitters in Venice, Louisiana. He also looks at the Rockwell hardness, a figure available for better blades. It’s a term used by metallurgists to quantify blade hardness. Quality consumer knives will typically range from 50 to 65 on the Rockwell scale. Newman uses AFTCO fillet knives rated as 56 to 58, hard enough to yield a finer edge and to hold that edge longer than blades with a lower Rockwell number.

Quality fillet knives combine some carbon with stainless steel, says Capt. Ryan Griffin, one of Southern California’s top watermen who also happens to be a professional chef. “This is required for optimal blade strength as well as sharpening capabilities. Stainless on its own is brittle and won’t hold an edge. Carbon is very dense and susceptible to oxidation.” So, combining the two metals in the right amounts is the solution, he says. Griffin also points out that it’s called stainless. All fillet knives will oxidize unless maintained properly after use.” That means cleaning with mild soap and fresh water, adding a thin layer of oil, and storing in a dry place.

Echoing how critical dry storage is for a knife’s longevity, Capt. Damon Sacco in Cape Cod, Massachusetts, the founder of Castafari Sportfishing, says, “Store your knives in a dry place — like your engine room instead of in a cabinet in your cockpit. I learned that one the hard way.”

Another feature of well-designed fish fillet knives: full-tang construction. That describes a knife with a blade that extends all the way through the handle. “That full tang offers a stronger knife and a better connection of blade to handle,” says Capt. Karl Anderson, a well-known South Florida expert. Other experts agree: good knives are full-tang knives.

Blade Length and Design

Figuring out the best blade length seems to be a matter of personal preference as well as the size of the fish. These experts show just how much the preference for blade length will vary. For Newman, shorter is better — “the shortest blade possible when filleting fish. I have more control with shorter blades.” Anderson also prefers a short knife: a seven-inch blade with flex “so I can cut along the backbone and make cuts close to the bone without tearing or slicing the meat because the blade is too big (too long or wide).”

Griffin has some use for his nine-inch knife, but prefers seven- and eight-inch blades, and will scale down to a six-inch blade for small jobs. Even for tuna, once he’s made initial cuts with a large blade, he’ll bring out his thinner six-incher to finish filleting.

Returning to the size of the fish to be cleaned as a determining factor in blade length, Sacco is an outlier in the group because he deals mostly with large tuna and swordfish, so understandably he’s all about 10- to 12-inch knives. Still, he often makes his initial cuts with a short but thick blade, then switches to a larger blade that offers some flex. For that, he says, AFTCO’s fillet knives meet the requirements for a blade both “strong enough to hold up and thin enough to remove the skin” (without damaging the fillet).

However, for many pros, there’s a major caveat about picking one length: Don’t. That is, having two or three knives of different lengths on hand can be essential. For example, Newman points out that when he’s ready to skin a fillet, he chooses a knife with the blade length appropriate for the width of that fillet. Anderson also often finds multiple blades the best way to tackle a particular job: “Recently we have been on a good run of larger blackfin tuna; for these, we use the larger 12-inch AFTCO knife to make the preliminary cuts from the pectoral to the head then down along the dorsal, through the thick skin. We then go back with the eight- or 10-inch knife to make the flesh cuts.”

Similarly, Griffin switches back and forth between a larger, heavier blade and a six- or eight-incher when filleting fish like grouper. With the larger knife, he traces the fillet to be cut, penetrating the thick skin. “Then I’ll switch to the smaller, flexible blade to slice the fillet to the rib bones, then go back to the larger, more rigid blade to break the rib bones from the spine,” he says. Then it’s back to the small knife to remove ribs from the fillet and, finally, the larger knife to remove the skin.

Fish fillet knives will be either straight or curved. Anderson is “definitely a curved-knife believer: The curved blade offers the most control and allows me to get in tight next to the backbone, without slicing into meat that isn’t right next to the bone, giving you a thicker, cleaner fillet.” Sacco also prefers a curved blade, though he says straight blades are a bit easier to sharpen.

Blade Thickness and Flex

Typically, the thickness of a fillet knife blade goes hand-in-hand with its flex. Heavier, thicker blades will be stiff, while the thinner the blade, the more flex it will offer. A thick blade’s stiffness is a big plus when cutting through fish with tough skin or heavy rib bones, but such a knife becomes a disadvantage with the finer work of separating flesh from bones along the spine.

Size of the fish isn’t the only factor dictating knife size/type; the type of fish makes a big difference. For example, even though they’re relatively small, the heavy bone structure of sheepshead call for a stiff knife, says Newman, citing the eight-inch AFTCO blade for such a job. But for filleting speckled seatrout, with a fragile bone structure, Newman prefers a thin seven-inch knife to avoid cutting through the trout’s skeleton while filleting.

“For smaller fish, the thinner the better,” Anderson says. Thin blades have enough flex for skinning fillets as well as cutting fillets away from the backbone whether at the center of the fish or along the outer edges.

Some pros rely heavily on knives that they feel offer a good compromise, thick enough to do heavier jobs while also with enough flex to work in close while separating meat from bone and from skin. Sacco says he’s found that the AFTCO Boker blades offer that compromise.

Handle

Not to be taken for granted, a fillet knife’s handle material and design are “very important,” Newman says. “It’s all about safety and control,” he adds. “A material that won’t become slippery from water or fish slime is key for safety.” He suggests looking for a handle shape that just feels right in your hand. And “a handle design that flares outward below the blade is key.”

A fillet knife’s handle shape and material are of great importance when cleaning fish large or small,” Griffin maintains. “It’s the difference between an injury or wrapping up a great day of fishing,” citing AFTCO knives’ handle material as the best. Griffin adds that the combination of a dull blade and subpar handle is a recipe for disaster. And with any handle, he advises, keep it clean and free of blood or slime.

Anderson recalls that “Most our handles on charter boats in the ‘70s were wood. I didn’t realize it then, but the repetitive nature of filleting a mess of fish with a small-handled knife after continually reaching into an icy fish box was tough on the hands.” Composite handles on later models were better, but Anderson says they still could be slippery. These days, “The new AFTCO knives offer me the best combination: they fit my hand ergonomically, offer a good grip, and are easy to keep clean.”

Thoughts on Sharpening

How regularly must your fillet knife, whatever its type or size, be sharpened? Depends on the filleter.

For Griffin, that usually means after every third or fourth cleaning job, but not immediately after; rather, just before a cleaning job, “I’ll get out a wet stone and redevelop the edge.” It’s a well-spent five minutes or so per knife.” However, he also maintains the edge by giving the blade a few licks with a honing rod throughout a filleting job. “My Dexter honing rod is always on the table when I'm cutting fish,” he says.

Anderson is a believer in working the blade a bit each time you use a knife. Then “before I put my knives back in the sheath, I touch them up to be sure they’re ready go.” He prefers a fine-grit ceramic stone for this.

Sacco takes a much different approach: “I sharpen a knife only when it feels dull and isn’t cutting properly.”

Each captain and pro has a knife sharpening process and preference, but to make the most of your investment, anglers should sharpen their knife frequently for the best results. Check out our guide on sharpening a fillet knife to learn more. 

Choosing the right fish fillet knife makes all the difference when prepping your hard-earned catch. With input and advice from these four fishing experts and captains, it's time to hit the water so you can start putting your new fish fillet knife to the test.