Large fish can be cut into quarters to yield four fillets each. Whole or quartercut fillets are usually skinned before they are prepared. Quartercut fillets are easier to skin because they are smaller. Flatfish fillets have a sweet, mild taste and should be handled carefully because of their fragile texture. Fillets from the dark side of a flatfish may have a slightly stronger flavor and, because of a more highly developed vascular system, may lose their quality faster than fillets from the white side.
Some anglers recommend using fillets from the dark side first.
Groundfish Groundfish is a commercial fishing industry term for the Gadoid family of fish especially Atlantic cod, haddock, pollock, and the hakes. These species are the primary targets of the offshore fishing fleet on fishing grounds like the Georges Banks. Cod, haddock, and pollock have white flesh and similar edibility characteristics. The hakes are similar in many ways to these three species, but they warrant a separate discussion because their texture and storage characteristics are different. Cod and haddock have long been the mainstays of commercial fishing in the North Atlantic.