What Are the Main Fillet Knife Uses?

Fillet knives are one of the most unique-looking kitchen knives on the market. Based on their name alone, you might be unsure of the specific fillet knife uses. If you have one of these knives in your collection or are interested in owning one, you should understand their true purpose.

Fillet knives are used to make delicate cuts through flesh and around bones. Their design is most suitable for cutting different types of fish. The sharp, serrated blade effortlessly penetrates skin and flesh. A fillet knife blade is slim to reduce friction and make clean cuts. The blade is also flexible so it can contour around bones.

Fillet knives are not limited to fish. They can be helpful with deboning some cuts of meat, for example, small chicken bones. It is not recommended to use a delicate fillet knife to cut very tough meats because it may snap. Meat and fish aside, a fillet knife is a very good tool for finely chopping vegetables and onions.

People often confuse fillet and boning knives, and who can blame them? We will compare these two types of knives to highlight the key differences so you can decide which suits your cooking better. Afterward, we will cover essential fillet knife maintenance plus the criteria to keep in mind when purchasing a fillet knife.

What is a fillet knife?

A fillet knife is a specialized type of kitchen knife that is designed to cut fillets off fish carcasses. The name fillet itself refers to a boneless cut of fish or meat ― exactly what a fillet knife is supposed to produce. A fillet knife can cut many ingredients but preparing fish is its main purpose.

A fillet knife has many elements in common with a standard chef knife with some visible physical differences. A fillet knife has two main sections: the blade and the handle. Its blade is usually 4-10” long.

Parts of a fillet knife

Blade

A fillet knife has a curved edge to increase the blade length and improve slicing efficiency. Some fillet knife edges have a subtle curve, while others have a very pronounced curve. Very curved fillet knives have spines that curve back as well ― this is unique among kitchen knives.

The spine itself is dull but is useful for scaling fish before butchering. Fillet knives sometimes have serrated edges with very fine teeth. The teeth help to cut through the tough skin and muscles of fish by creating many small tears to reduce resistance.

The tip of a filleting knife is the round section at the end of the blade that finishes with a sharp point. The tip is great for finely chopping vegetables and scoring. The point is used to pierce through tough fish skin and flesh.

Handle

The handle is the interface between a user and their blade. The tang is the core of the handle and is directly attached to the blade (it is part of the same piece of metal). The tang is either partially surrounded by scales or fully concealed by the handle material.

Filet knives can have a full tang, which is the same length and width as the handle, or a partial tang, which is thinner and shorter. The tang changes the knife’s center of gravity ― a full tang is considered more balanced.

Many fillet knife models have a finger guard or handle guard (or both). The finger guard is a section that sticks out at the top of the handle. Its role is simple: to stop your hand from sliding up to the sharp blade. The handle guard is similar; this section sticks out at the bottom of the handle and prevents your hand from slipping and possibly dropping the knife.

The finger and handle guards create a secure slot for your hand so that it will not move in either direction. This is an important safety feature of the handle since your hand may slip when

Fillet knife uses

Filleting

A fillet knife’s primary use is cutting fillets from the carcass of a fish. That is, to cut away a boneless piece of fish that is ready for cooking. The design of a fillet knife lends itself to careful and precise cutting; the narrow blade reduces friction to make clean cuts through the soft flesh. The blade is also flexible and so can adapt to many shapes and sizes of fish.

Gutting & scaling

With certain types of fish, it is necessary to remove the internal organs before cutting fillets. The sharp tip section of a fillet knife is excellent at slicing open the belly of a fish to reveal the organs.

Although dedicated scaling tools exist, few home cooks own one. Scaling is an important initial step when preparing some fish. Luckily, the blunt spine of a filleting knife can work as a scaling tool.

Deboning

A fillet knife is technically not a boning knife but is quite similar (see below). Hence, it can be useful for deboning fish ― its thin and flexible blade is adept at penetrating small gaps and extracting the tiniest bones. In addition to bones and flesh, you can use a fillet knife for gutting fish since it cleanly slices through the tough skin.

Fish are not the only animals that a fillet knife is useful for. However, it is not as sturdy as a boning knife. A fillet knife can probably slice through chicken breasts but would struggle with the tougher cartilage. It is unsuitable to use a fillet knife for tougher cuts of meat like beef and lamb.

Preparing fruit & vegetables

Aside from meat and fish, the slender blade of a fillet knife can produce thin slices of fruit and vegetables. For example, you could finely chop garlic and tomatoes. You could also thinly slice tomatoes, bananas, and strawberries. 

You should be careful with chopping firmer items like apples, potatoes, carrots, or watermelons. These ingredients can damage or even snap the somewhat flimsy blade.

How to fillet a fish

This is a very broad topic given how many species of fish there are. Each fish carcass provides two edible fish fillets. The rest of the body (except the guts) can be useful for making fish stock.

Firstly, you should use the knife’s spine to remove the scales. Turn the knife around and run the spine along the surface of the fish, making sure to move against the grain of the scales.

Once the fish is clean of scales, you can remove the guts (this is not recommended for certain types of fish). Scissors are the most effective tool for this job. Cut down from the gills towards the tail and be careful not to tear too many organs. Pinch and twist the gills with the scissors and then pull them out. You may want to clean the remaining blood.

To free a fillet, you need to cut underneath the collar of the fish (behind the gills). Then, slice along the backbone and under the skin down to the tail. Use your fillet knife to carefully peel the fillet off the rib cage, not leaving any flesh behind.

Every fish has slightly different anatomy and therefore needs a unique approach to filleting. For specific steps for most types of fish, use this guide as a reference.

Fillet knife vs boning knife: how are they different?

Fillet and boning knives look fairly similar and can both be used to prepare fish. The difference between the two is not always clear-cut. There is a lot of overlap between the two knives, and some models can act both as a fillet and boning knife.

The table below shows how these tools differ. If you want a more in-depth comparison, take a look at our article on this topic.

	Fillet knife	Boning knife
Blade length	4-10”	5-9”
Blade width	0.5-1”	1-1.5”
Blade shape	A very thin blade with a pronounced upward curve. The spine also curves up at the end of the blade (on certain models).	A thin blade with a flat spine. The edge gradually curves up towards the point. The curve is more obvious in the tip section.
Edge type	Usually serrated. The edge is curved to maximize the cutting surface. At the bottom of the blade, you will often see a finger guard	Usually smooth. These knives can feature finger guards as well.
Flexibility	Fillet knives are flexible because they must carefully cut fillets from many types of fish.	Boning knives are stiffer than fillet knives because they need to slice through tougher cuts of meat.
Material	A fillet knife needs to work in a wet and oily environment. Its blade, therefore, should be corrosion-resistant.Stainless steel is an excellent choice of metal because it does not rust easily and is soft (hence flexible).	When manufacturing a boning knife, hardness and rigidity are prioritized over flexibility.The wider boning blade is stiffer than that of a fillet knife. It is even stiffer when made from carbon steel. Although, they can also be made with stainless steel.
Uses	Filleting, gutting, and de-boning fish. It can also be useful for chopping or slicing certain fruits and vegetables.	De-boning meat. This could also be used to prepare fish since it shares many features with the fillet knife.A boning knife can handle harder vegetables than a fillet knife.

How to care for a fillet knife

Your fillet knife needs the same maintenance, care, and storage as your other knives, even if you use it less often. If you keep the blade sharp, clean it thoroughly after every use, and store it in a secure place, it will perform well for years.

How to sharpen

A fillet knife has a very narrow blade, so you should not sharpen it too often to avoid wearing it down. Still, a sharp blade is crucial for making clean cuts.

The standard sharpening technique uses a whetstone. While holding the knife at the correct bevel angle, run the blade gradually along the corner of the whetstone, starting with the rougher side. After you have slid the knife across both sides of the whetstone several times, it is a good idea to rinse the blade with warm water.

If you do not have a whetstone, there are some brilliant DIY sharpening methods that you can try. For instance, the bottom of a plate or mug is a good substitute for a whetstone. We covered these methods in detail here.

Note that the curved blade of a fillet knife makes sharpening more tricky since you cannot use a simple back and forth motion.

How to clean & store

There are plenty of good storage options for your fillet knife. Instead of placing it in a drawer, you can hang it on a knife rack or keep it in a knife block. There are also ingenious under-cabinet storage methods.

As for cleaning, wash your fillet knife soon after use, especially after preparing raw fish. Wash it by hand with hot water and soap. Following this, you should dry it with a clean towel to minimize the chances of corrosion.

How to choose a fillet knife

Size

Your blade should ideally be longer than the width of any fish you prepare. For most cooks, a blade in the 6-8” range is perfect.

Blade

The choice between carbon and stainless steel is a trade-off between hardness and corrosion resistance. A stainless steel blade requires less maintenance but will lose its edge faster.

In regards to the shape, a very curved fillet blade is more optimized for cutting fish but is more difficult to sharpen. Remember, some boning knives can also work as filleting knives, so if you don’t plan to prepare much fish, that may be a better option for you.

Handle

A partial tang knife is lighter, though less balanced than one with a full tang. Everyone has their preference when it comes to the weight of a knife.

An ergonomic handle with finger grooves may be more comfortable but less aesthetic for some people. The same is true of certain materials; what looks good might not feel great. It is all a matter of choice.

Summary

Most cooking tasks can be completed with a standard chef knife, although a fillet knife can be a welcome addition to your knife set. If lots of your meals are based on fish, nothing can beat the delicate and precise cuts of a fillet knife.

If you only plan to use your fillet knife occasionally, you can opt for a cheaper model. Nowadays, there are plenty of options on the market for every budget. If you maintain your fillet knife, it will be a worthwhile purchase.