How to Butterfly a Fish: Step-by-Step Butterfly Cut Guide
To butterfly a fish, you remove the backbone and ribs while leaving the two fillets joined, so the fish opens flat into one bone-free piece. Run a sharp fillet knife along each side of the spine, then snip the bone free with kitchen shears.
Butterflying (also called splitting) is close cousin to filleting a fish — the difference is that you end up with one connected, flat fillet instead of two separate ones. It is the cut you want for stuffing a whole fish, grilling it flat, or cooking mackerel, trout, branzino and sardines evenly without diners picking out bones. Here is how to do it cleanly, updated for 2026.
What is a butterfly cut on a fish?
A butterfly cut removes the spine and rib bones from a gutted fish while keeping the two sides attached — usually along the back or the belly. Opened out, the fish resembles a butterfly: flat, even thickness, skin on one side, flesh on the other. Because the fish cooks flat, it cooks fast and evenly, and because the bones come out before cooking, everyone eats without hunting for pin bones.
What you need
A flexible, razor-sharp fillet knife does the fine work along the bones — ours is the 7" Bushcraft Fillet Knife, hand sharpened and oiled before it ships like every blade we forge. Add kitchen shears for the spine, tweezers for pin bones, and a cutting board with a damp towel underneath so nothing slides. A cut-resistant glove on your guide hand is cheap insurance.
How to butterfly a fish, step by step
1. Start with a gutted, scaled fish
Scales and guts must go first — your fishmonger will do this in seconds if you ask. Remove the gills, and rinse and dry the cavity so your knife will not slip.
2. Extend the belly opening
Lay the fish on its side and run the tip of your fillet knife from the gutting cut down to the tail, opening the belly fully without piercing through the back skin.
3. Free the ribs on the first side
Working from the cavity, slide the blade flat along the rib cage, letting the bones guide the knife. Use long, shallow strokes — you are separating flesh from bone, not sawing.
4. Free the second side
Flip the fish and repeat on the other rib cage, keeping the back intact so the two sides stay joined.
5. Cut along the spine
Angle the knife along each side of the backbone from head end to tail, releasing it from the flesh while leaving the skin along the back uncut.
6. Remove the backbone with shears
Snip the spine at the head and tail ends with kitchen shears and lift it out in one piece, ribs and all.
7. Pull the pin bones and open it flat
Run a fingertip against the grain of the flesh to find stray pin bones and pull them with tweezers. Open the fish out flat — it is ready to stuff, grill or pan-roast.
Butterfly cut vs filleting: which should you use?
Fillet when you want individual portions or skinless pieces; butterfly when you want the whole fish cooked as one — stuffed, flattened on a grill, or served dramatically whole. Butterflying also wastes less meat, since nothing is trimmed away from the bone twice.
Common questions
Can you butterfly a fish with the skin on? Yes — the skin is what holds the two sides together. Leave it on; it crisps beautifully and keeps the flesh moist.
Which fish are best for butterflying? Round fish with soft rib bones: trout, mackerel, branzino, snapper, sardines and small salmon. Flatfish are better filleted.
Do I need a special knife? You need a thin, flexible, genuinely sharp blade — a stiff chef knife will tear the delicate flesh. A dedicated fillet knife pays for itself the first time you break down a catch.
Shop the range
Every blade from The Cooking Guild is hand sharpened and oiled before it ships — the sharpest blades you will ever use, or your money back. Try the Bushcraft Fillet Knife or browse the full utility & fillet knife collection with a 99-day home trial and a free lifetime guarantee on every knife.
Keep reading: How to Choose the Best Knife for Outdoor Cooking and Survival · How to Maintain and Care for Your Knife Outdoors (Rust, Edge, Storage)
Keep building your knife skills: how to fillet a fish · 6 basic knife safety rules
Kitting out for the outdoors: The Essential Knives Every Outdoor Cook Needs (From Campfire to BBQ)
