What is a Deba Knife? Introducing the recommended size for beginners, the difference between steel and stainless steel, and how to use it

A "deba knife" is necessary for filleting and other fish preparations . It is a sturdy knife that can cut through the bones and head of a fish, but when it comes to choosing one, you may be unsure about whether to get one in steel or stainless steel, or whether to get one in 150mm or 180mm.

In fact, the best rod will vary depending on the size of the fish you want to fillet and the time you have available to care for it.

For example, if you mainly use small fish such as horse mackerel, you should choose a small deba knife; if you want to fillet medium-sized fish such as sea bream and yellowtail, you should choose the versatile 150mm medium deba knife; and if you want to reduce the effort required for maintenance, you should choose a stainless steel knife .

In this article, we will thoroughly explain the different types of "deba knives," how to choose one for beginners (size, material, dominant hand), how to use it, and how to care for it.

What is a deba knife?

A deba knife is a type of traditional Japanese knife that is made specifically for the purpose of filleting fish .

The name is said to have come from the fact that the blacksmith in Sakai who invented this knife during the Edo period had bucktooth, and so the name "deba knife" came to mean "a knife made by a craftsman with bucktooth."

A thick, heavy Japanese knife specially designed for filleting fish

The biggest feature of a deba knife is that its blade is overwhelmingly thicker and heavier than ordinary household knives (such as a santoku knife or a chef's knife).

For example, it is not uncommon for a deba knife to weigh more than twice as much as a Western knife (gyuto) of the same length. The reason it is so thick and heavy is to withstand the impact of cutting through the hard bones and head of a fish, and to prevent the blade from chipping or bending .

Furthermore, by using this axe-like weight, you can easily cut through tough fish heads and bones without using much force.

Why do we need a deba knife? Its unique structure (single-edged blade and back-slit)

The reason why a deba knife is easy to use for filleting fish is due to its special structure.

■Single-edged structure:

Like many Japanese knives, deba knives are essentially "single-edged," meaning that only one side of the knife (usually the front side for right-handed knives) has a sharp edge, while the other side is flat (or concave).

This single-edged design allows the blade to dig deep into the fish's flesh, separating it along the bone, allowing for a clean filleting without leaving any meat on the bone.

The sharp single-edged blade cleanly cuts through the fibers, preventing the fish's flavor (drip) from escaping and eliminating any fishy smell. The cut surface becomes smooth like a mirror, and even the texture changes to make it delicious .

■Urasuki (Urasuki):

The back of a single-edged knife is not completely flat, but has a slight depression. This depression makes it difficult for the food (fish flesh) being cut to stick to the knife , reducing resistance and allowing for smoother cutting.

Simply slide the blade along the bone, and the blade will move like it's running on a rail, allowing anyone to easily and neatly peel the fish flesh.

This combination of a single-edged blade and a back-slit is what makes a deba knife ideal for filleting fish .

Main types of deba knives

Deba knives are further divided into different types depending on the size of the fish to be filleted and the purpose.

Deba knife: the most standard type

This is the most standard type of knife, commonly known as a "deba knife." The blade is thick and heavy enough to be used for cutting off fish heads and cutting through bones.

Aio Deba Knife: Slightly thinner than Hon Deba, and easy to handle

The "Aideba knife" is a type of knife with a blade that is slightly thinner and slimmer than a Hon-Deba knife. It is somewhere between a Hon-Deba and a Mioroshi-Deba , and is not as heavy as a standard Deba knife, making it easy to handle.

Oshiori Deba Knife: Even thinner, can also be used for filleting

The Mioroshi Deba knife is even thinner and slenderer than the Ai Deba knife (similar in shape to a sashimi knife). It is designed not only to fillet fish, but also to cut it into fillets and sashimi.

However, because the blade is thin, it is not suitable for cutting through thick bones like a real deba knife.

Small Deba Knife/Horse Mackerel Slicing Knife: For small fish such as horse mackerel

This is a very small "kodeba knife" with a blade length of about 9cm to 13cm. As its name suggests, it is specialized for delicate work such as filleting and gutting small fish such as horse mackerel, sardines, and whiting, and is very maneuverable.

How to choose a deba knife

Deba knives come in a huge variety of sizes and materials, so choosing your first one can be difficult. Here are three points to help beginners avoid making mistakes.

Point 1: How to choose the size (blade length)

If you have a clear idea of ​​the fish you want to fillet, it's best to choose a knife based on the size (especially the vertical width) of the fish .

• 90mm to 135mm (small deba) : For small fish such as horse mackerel, whiting, sardines, squid, and cutlassfish.
  
• 150mm-165mm (medium blade) : For medium-sized fish such as sea bream, mackerel, pufferfish, and yellowtail
  
• Over 180mm : Large fish such as yellowtail, tuna, and kingfish

*Sizes over 180mm are very heavy, so we recommend that you check the weight before purchasing.

■If you haven't decided on the fish you're going to fillet (this is your first fish), the 150mm is the all-purpose size.

If you want to start filleting fish but don't plan on just one specific type of fish, you can't go wrong with a 150mm (15cm / 5 sun) deba knife.

The 150mm length can accommodate a wide range of fish, from small fish such as horse mackerel and sardines to medium-sized fish (up to about 50cm) that are often handled at home, such as sea bream and yellowtail.

*Why is "bigger is not better"? When choosing a knife, we tend to think "bigger is better," but when it comes to Deba knives, "bigger is not better."

For example, let's say you buy a large 210mm (7 sun) deba knife for cutting large fish like yellowtail. If you try to use this knife to fillet a small horse mackerel, the knife is too big and you can only use the tip, making it very difficult to handle and inefficient.

In that respect, a 150mm knife can handle large fish, although it will require a few more strokes, but there is almost no inconvenience when filleting small fish. This good balance is why the 150mm is called the "all-purpose size."

Point 2: How to choose the material (steel) (steel vs stainless steel)

Once you have decided on the size, the next thing to consider is the blade material. Let's understand the advantages and disadvantages of both steel and stainless steel.

■ Steel type: Shirogami steel, Aoni steel, etc.

• merit:
  Sharp: When sharpened, the sharpness surpasses that of stainless steel.
  Easy to sharpen: It adheres well to the whetstone and regains its sharpness easily, making it ideal for sharpening practice.
  Tough (such as blue steel): Some steels are "tough" and have the property of being resistant to chipping when they come into contact with bone.
  
  
• Cons:
  Very susceptible to rust: This is the biggest drawback. It is so delicate that rust will appear if you leave it wet for just 10 to 15 minutes. It is essential to wash it immediately after use and wipe off all moisture.

■ Stainless steel: Ginsan, molybdenum steel, etc.

• merit:
  Extremely rust-resistant: This is the biggest advantage. It is very easy to maintain after use, so you don't have to worry about it.
  Hygienic: All-stainless steel handles have no seams, making them easy to clean and hygienic.
  
  
• Cons:
  Sharpness and ease of sharpening: Compared to steel, it is generally inferior in terms of sharpness and ease of sharpening (ease of sharpening the blade).
  (Note: In recent years, technology has advanced and high-quality stainless steel comparable to steel is now available.)

■ Why experts recommend "steel" (frequency of use and ease of sharpening)

For beginners, "stainless steel" is often recommended as it is easy to maintain, but many knife experts also recommend "steel."

The reason is that a deba knife is not used "every day, morning, noon and night" like a santoku knife. If you use it "a few times a month" or "once a week," you only need to take care of rust when you use it, so the disadvantages of steel are relatively easily offset.

Rather, it is thought that the benefits of steel, such as its ease of sharpening and its resistance to chipping (the toughness of the steel), come into play precisely because the blade of a deba knife is subjected to stress.

Point 3: Blade structure (single-edged vs. double-edged) and dominant hand

The way the blade is attached is also an important point that is unique to Japanese knives.

■ Single-edged blade (the basic Japanese knife): Easy to cut along the bone

All traditional deba knives are single-edged. The asymmetrical design, with the blade on only one side, allows the blade to fit snugly against the bone, enabling the "three-piece filleting" technique, which involves removing the meat without any waste.

■Double-edged (Western Deba): Suitable for both dominant and left-handed users

There are also some deba knives (Western deba) that have the same "double-edged" edge as Western knives. Because they are symmetrical, they can be used with either hand and are suitable for cutting straight through bones, but the feeling of cutting along the bone is different from that of a single-edged knife. For your first knife, we recommend a "single-edged" knife, which is the basic Japanese knife.

■Left-handed people should always choose "left-handed"

Single-edged knives are clearly divided into "right-handed" and "left-handed" types due to their structure. It is structurally impossible to use a right-handed knife with your left hand (the blade would move away from the bone).

If you are left-handed, be sure to choose a product that is clearly marked "for left-handed use" when purchasing.

The difference between a deba knife and other knives

When it comes to "filleting fish," the Deba knife is a specialized tool that excels all other knives. Its purpose and structure are fundamentally different from the Santoku knife you might have at home or the sashimi knife, which is also a Japanese knife for fish.

Differences from Santoku knives (thickness, weight, blade structure)

The Santoku knife, which is the most commonly used knife in the home, and the Deba knife, which is specifically for cutting fish, have fundamentally different purposes and structures.

• Deba knife = A knife used to fillet and slice fish. It is characterized by its very thick and heavy blade. It is designed to be sturdy enough to cut through the head and hard bones of fish. Many of them also have a single-edged structure, allowing you to cut cleanly along the bone to remove the flesh.
  
  
• Santoku knife = A versatile knife for "cutting" ingredients. It is characterized by a relatively thin and light blade. It is designed to smoothly "cut" various ingredients such as meat, vegetables, and fish (excluding bones). Most have a "double-edged" structure, allowing the blade to cut straight into ingredients.

Never try to cut through fish bones with a Santoku knife (the blade is too thin and will definitely chip).

Conversely, it is difficult to julienne vegetables with a deba knife (the blade is too thick and the food will break). The correct way to use them at home is to use a deba knife to fillet fish and a santoku knife to cut vegetables and meat.

Differences from a sashimi knife (yanagiba knife) (Use: cutting vs. pulling)

Deba knives and sashimi knives (yanagiba knives) are both Japanese knives used to cut fish, and while most are single-edged, their roles are clearly separated.

• Deba knife = A knife for "filleting" fish. It is characterized by its thick and heavy blade. It is a knife that emphasizes durability for cutting off the head of a fish and separating the flesh from the bones (filleting).
  
  
• Sashimi knife = a knife for "pulling" sashimi. Its blade is very thin and long. This is because the "saku" (block of meat) after filleting with the deba knife is cut in one direction with a "pulling cut." The thin blade does not crush the fibers of the meat, allowing for the creation of sashimi with a beautiful, sharp cross section.

It is difficult to cut sashimi with a deba knife (the blade is too thick and the flesh will be crushed), and it is absolutely impossible to cut bones with a sashimi knife (the blade is too thin and will definitely chip).

In Japanese cuisine, the division of roles is clearly defined: "cutting with a deba knife and cutting with a sashimi knife."

Basic usage of a deba knife

The shortcut to mastering the use of a deba knife is to understand its unique shape. In particular, it is important to know how to use the blade properly and how to cut bones.

A single knife with two distinct blades: the base and the tip

The role of a single deba knife varies depending on the part.

• Chin (base of blade): This is the thickest and strongest part of the blade, located near the handle. This is used for powerful striking, such as chopping off a fish's head or breaking through hard bones. Some professionals even use this part as an area where it's okay to chip.
  
  
• Tip (edge): This is the part near the tip where the blade is relatively thin and sharp. This is used to fillet the fish and separate the meat from the bone, and for other fine work. Because sharpness is important, this is the part that must not be chipped, so handle it with care.

[Preventing chipping of the blade] The trick to cutting hard bones is to aim for the "joints"

Deba knives are sturdy, but if you try to forcefully cut through a very hard bone like the backbone of a sea bream, the blade may chip (or chip) .

The biggest trick to preventing chipping of the blade is to aim at the joints between the bones .

Just like a human spine, a fish's spine has joints at various points. If you hold the blade upright and find the joints, you can cut through the bone without using much force (just the weight of the knife).

How to care for and store a deba knife

If you choose a deba knife, especially one made of steel, proper care is essential to maintain its performance. Learn the correct care and storage methods to enjoy your precious knife for a long time.

To prevent rust, do the following immediately after use:

Rust is the biggest enemy of a steel deba knife. Steel rusts easily, and rust can appear if you leave it wet for just 10 to 15 minutes.

The most important thing to do to prevent rust is to wash it immediately after use and dry it thoroughly .

1. Wash immediately : Fish oil and blood can cause rust, so scrub thoroughly with mild dish soap and a sponge after use to remove any dirt.
2. Dry completely : This is the most important thing. After washing, use a dry cloth (cloth or towel) to thoroughly wipe off all moisture from the blade and handle (especially the base).
3. Wipe while using : While you are filleting fish, keep a tightly wrung out wet cloth nearby and frequently wipe away any moisture or dirt from the blade to significantly reduce the risk of rust.

Basic sharpening methods for Deba knives (how to choose a whetstone and how often to sharpen)

No matter what kind of knife you use, the sharpness will inevitably decrease. To maintain its sharpness, it needs to be sharpened using a whetstone.

• How to sharpen : Most deba knives are single-edged, and are sharpened differently from double-edged santoku knives. The basic rule is to sharpen the "front side" where the blade is attached, and not sharpen the opposite "back side" (ura-ski) too much, just enough to remove any burrs (burrs caused by sharpening) (= ura-oshi).
• Recommended sharpening frequency: Frequency varies depending on usage.
• When you feel that the sharpness has decreased : This is the basic timing.
• After filleting small fish several times : As long as the blade is not under too much strain, a rough guideline is about once every five fillets.
• If you cut a large fish bone , the blade edge is likely to be chipped or damaged to an invisible level. We recommend that you resharpen the blade as soon as possible after use.

Be careful of cracks in the handle, which can shorten the life of your knife!

Experts point out that the most important problem to watch out for with a deba knife is a cracked handle .

1. Deba knives put a lot of strain on the base of the handle (muzzle) because they use their heavy blade to strike bones and other objects.
2. The impact causes a small gap (crack) at the base of the handle.
3. Moisture from dishes and other items can seep in through the gaps.
4. The internal metal part (core) rusts and expands.
5. The expanding metal pushes the wooden handle apart from the inside, causing the handle to crack open.

If you leave this condition and the internal core breaks, it will be almost impossible to repair and the knife will reach the end of its life. If you notice even the slightest crack or gap in the handle, please consult a knife specialist immediately.

Correct storage method (storage using newspaper or oil)

This is the storage method for knives (especially steel knives) when they will not be used for a long period of time. Be sure to wash and dry them thoroughly before storing them.

1. Wrapping in newspaper: This is the easiest and most effective method. The oils in the ink in newspaper act as a rust preventative. Wrap the knife in newspaper and store it in a well-ventilated, dry place (such as a kitchen drawer).
2. Applying oil: Apply a thin layer of camellia oil or anti-rust oil specifically for knives to the entire blade.

Some users make their own sheaths to store their firewood, but it's best to start with newspaper.

Frequently asked questions (FAQ) about Deba knives

We will answer questions that beginners often have about deba knives.

Q. Can I cut vegetables or frozen foods with a deba knife?

A. We do not recommend this. In particular, never cut frozen foods.

The blade of a deba knife is thick and sturdy, but this is only to ensure it can withstand fish bones. If you try to cut something very hard, like frozen food, the blade will chip (chipped).

Also, avoid hard vegetables like pumpkins as they can damage the blade. The blade is too thick and not suitable for slicing or julienne vegetables.

Q. Is it enough to just buy a small deba knife?

A. It is sufficient if you are only filleting small fish such as horse mackerel or whiting.

Small deba knives (135mm or less) are very easy to handle when filleting small fish, but due to their size they are too small to fillet medium-sized fish such as sea bream or yellowtail, and the force cannot be transmitted well.

If you plan to fillet a variety of fish, we recommend the versatile 150mm size as your first rod.

Q. Why do professionals carry two knives (one for cutting and one for hitting)?

A. This is to "maintain sharpness" and "optimize use."

Professional chefs use two types of deba knives: one for cutting the flesh (emphasis on sharpness) and one for hitting the bones and head (emphasis on durability).

The process of "pounding" the bones will inevitably damage (chip) the blade, even if it is not visible to the naked eye. If you use a damaged blade to fillet the fish, the cells of the fish will be crushed, resulting in an unclean cross section.

This is because it is possible to make adjustments such as sharpening the blade for cutting to a very sharp edge, and sharpening the blade for striking to a deliberately blunt angle (to make it sturdy and less likely to chip).

Q. Can I fillet a large fish (such as yellowtail) with a 150mm knife?

A. It's not impossible, but it's not recommended.

The 150mm is just an all-purpose size, but it is too small to fillet large fish like yellowtail. Because the blade is not long enough, it cannot reach the bone in one go, which means you have to cut the fish multiple times, which is inefficient.

If you frequently fillet large fish, it is best to choose a size of 180mm (6 inches) or more.

Q. What should I do if my steel knife rusts?

A. If the rust is light, it can be removed with commercially available cleanser (polishing powder) or rust remover.

You can try rubbing the rusted area with a sponge or cloth and applying some cleanser. However, if the rust has penetrated deeply, you will need to use a whetstone to grind it off.

It is more important to "prevent rust from forming" than to "remove it after it has formed." Make it a habit to wash the item immediately after use and wipe off all moisture.

Summary: Choose the best one and try your hand at filleting a fish

A deba knife is a specialized tool packed with the wisdom of our ancestors for deliciously filleting fish. Filleting fish, which can be difficult with a santoku knife, becomes surprisingly smooth once you get your hands on a deba knife.

When choosing your first one, keep the following points in mind:

• Size: If you haven't decided on the fish you want to fillet, the versatile 150mm is the best choice.
  
• Material: For ease of maintenance, choose stainless steel. For sharpness and ease of sharpening, choose steel.
  
• Handedness: When choosing a single-edged knife, if you are left-handed, be sure to choose the left-handed version.

Find the one that's the perfect partner for you and try your hand at making authentic fish dishes.