Filleting and Portioning Fish

Traditionally, roundfish are primarily cut into fillets (boneless sides) or steaks, or served whole. (Steaks, which are not shown here, are made by cutting across the fish with a large, sharp knife, through the backbone, into slices of the desired thickness. Very large fish, such as swordfish and tuna, are filleted: The large, wedge-shaped fillets are then cut crosswise into slices.) Flatfish are classically portioned into fillets or sections, as the structure of the fish does not allow for vertical slices.