Flex is the specification, and it is chosen by the job
These two knives look alike and are chosen by a property that photographs badly: flex. A stiff boning blade drives between joints and along bone without wandering; a flexible filleting blade follows the ribcage of a fish and lifts a fillet whole. Buying the wrong one makes both jobs harder, and no amount of sharpness compensates. Length follows the animal — 13 to 15 cm (5.1 to 5.9 in) for poultry and small joints, 18 to 20 cm (7.1 to 7.9 in) for a side of fish. The third requirement is a grip that holds when wet and greasy, which is why so many professional versions are molded plastic rather than wood. We compare flex, length and taper, grip material, stated steel and corrosion resistance.
15 cm (5.9 in) · X55CrMo14 steel · stated 56 HRC · flexible · curved blade · ErgoGrip handle
The only knife in this hub that publishes both its steel designation and its hardness: X55CrMo14 at a stated 56 HRC, flexible, with a curved blade that lengthens the cutting stroke.
Best for: Skinning, trimming sinew and separating poultry.
≈ $23
18 cm (7.1 in) · Japanese powder steel · 2.2 mm (0.09 in) blade stated · slightly curved · laser-engraved pattern
An 18 cm (7.1 in) fish fillet knife in Japanese powder steel with a stated 2.2 mm (0.09 in) blade — the only thickness figure published in this hub.
Best for: Filleting whole fish, for someone who will keep it away from bones.
≈ $50
15 cm (5.9 in) · straight flexible blade · narrow · Fibrox non-slip handle · stainless
A 15 cm (5.9 in) straight flexible blade with the Fibrox handle — the grip that professional kitchens buy Victorinox for, on the knife most likely to be used with wet hands.
Best for: Filleting fish and jointing poultry, with wet hands.
≈ $39
18 cm (7.1 in) · high-carbon 10Cr stainless · thin blade · ergonomic handle · fish and boning
An 18 cm (7.1 in) fillet and boning knife in high-carbon 10Cr stainless, with a thin blade and a handle shaped to reduce fatigue over a long job.
Best for: Someone who fillets fish regularly and wants a harder edge than a European blade.
≈ $66
18 cm (7.1 in) · Damascus core with 67 forged layers · stated 12° per side · genuine forged pattern
The top of this hub: an 18 cm (7.1 in) Damascus fillet knife with 67 forged layers, a stated 12° edge per side, and a maker who states the pattern is forged rather than etched.
Best for: A cook who fillets often, sharpens their own knives, and wants a beautiful one.
≈ $90
A fillet is lifted in a single pass along the bone. A blade longer than the fish gives a clean cut where a short blade hacks.
Boning is done by going round the joint, in very little space. A short, rigid blade stays under control where a long one becomes dangerous.
A stiff blade skips off a bone instead of following it; an over-flexible one folds at a joint. The stated flexibility is chosen according to whether you fillet a fish or bone a leg.
Flexible for fish, rigid for meat and poultry. A semi-flexible model is an acceptable compromise if you only take one.
13 to 15 cm (5.1 to 5.9 in) is enough: the work is done in very little space, around the joints.
18 to 20 cm (7.1 to 7.9 in), ideally longer than the fish, to lift the fillet in a single pass.
With difficulty and more waste. The thick blade does not follow the bone and takes flesh with it.
Never with these blades: they go around bone, they do not go through it. A cleaver or poultry shears are made for that.
Gentle, frequent honing, without forcing a blade that bends. The edge is maintained more than it is remade.
More than on any other knife: you work on fat and wet surfaces, with a thin blade. It is a safety criterion.
A twenty-centimeter flexible blade fillets a whole fish and copes with poultry; a rigid thirteen-centimeter one does the opposite. Starting with the flexible one covers the most situations.
Flexible for fish, rigid for meat: that is the only rule that really counts here. The blade goes around the bone, it never goes through it, and a non-slip handle is a safety criterion on greasy work.
We show a column only when four utensils in five publish its value. The rest would stay empty and settle nothing.
| Model | Price | Blade length | Use |
|---|---|---|---|
| F. Dick FB032 | $23 | 15 cm (5.9 in) | Separating meat from bone, skinning, removing sinew |
| Victorinox 5.6413.15BK | $39 | 15 cm (5.9 in) | Fine portioning of fish and poultry |
| SANMEIHO SMHCS-2025-03-5 | $50 | 18 cm (7.1 in) | — |
| HOSHANHO Couteau à Filet 18cm | $66 | 18 cm (7.1 in) | Fish filleting and boning |
| SHAN ZU SZPCS-2017-036 | $90 | 18 cm (7.1 in) | Filleting fish and boning meat |
Specifications: manufacturer sheets for cookware and kitchen knives and the matching Amazon product pages. Prices and availability: Keepa. Every figure in this table names its source.
Most recent revision in this category: September 3, 2026.
Prices quoted in these summaries are dated readings. The live price is shown next to each product.
