Filleting a Flatfish

Filleting a flatfish is the technique of removing the four fillets from a fish such as sole, turbot or flounder. Because the fish is flattened and its backbone lies along the centre, the fillets are separated by following the skeleton from the centre line toward the outer edges. The aim is to produce clean fillets while leaving as little usable flesh as possible on the frame.

Preparation and tools

Use a stable, sanitised cutting board and a sharp, flexible filleting knife. Check that the fish has been properly received, chilled and prepared. Depending on the species and recipe, scale, gut and remove the head before filleting, or leave the head attached for certain presentations. Keep the fish cold throughout fabrication.

Basic method

1. Place the fish securely on the board, with the darker or upper side facing up.
2. Make a controlled incision along the centre line from head end toward the tail, following the backbone.
3. Starting at the centre, use short, controlled strokes to follow the rib bones and release the first upper fillet toward the outer edge.
4. Repeat on the other side to remove the second upper fillet.
5. Turn the fish over and repeat the process for the two underside fillets.
6. Trim the fillets, remove pin bones if present and check carefully for any remaining bones.

Yield and quality control

Flatfish yield depends on species, size, condition, trimming standard and whether the skin is retained. Keep the frame, head and suitable trimmings for fumet when appropriate, removing gills, blood and unsuitable tissue first. Weigh the usable fillets and record yield when standardising purchasing and food cost.

Example: a whole Dover sole is commonly skinned and filleted into four portions before cooking or service.

Chef’s tip: keep the knife close to the skeleton and use steady strokes rather than sawing. A clean technique improves yield and produces fillets with fewer ragged edges.

Food-safety note: keep fish chilled during fabrication, sanitise tools and surfaces, and separate raw fish from ready-to-eat foods. Follow the required controls for any raw or undercooked service.

Key distinction: flatfish are commonly fabricated into four fillets; round fish generally produce two main side fillets.