Preparation of Fish and Fillet; Round, Dover & Flat Fish

The range of fish available to the caterer is extensive and is in no way limited to those varieties discussed here. The types of fish selected for discussion are those most commonly used within the catering industry and are aligned with specific principles, methods and dishes — and, it is hoped, good trade practice.

Fish may be classified in a number of different ways, e.g. marine or fresh water, or according to their shape — tapering, arrowshaped, flat, round. In professional cookery it is generally accepted that fish are categorised under two main headings:

(a) shellfish, further subdivided into crustaceans and mollusks;
(b) other fish further subdivided as follows:
(i) oily fish, e.g. mackerel, red mullet, salmon, salmon trout, trout, skate, whitebait;
(ii) white fish, e.g. brill, cod, haddock, halibut, hake, lemon sole, Dover sole, plaice, turbot, whiting.

These categorizations provide a handy guide to specific methods of cooking and styles of serving but should not be treated as hard and fast rules as there are exceptions. Generally those fish listed as oily are not suitable for deep fat frying, but apart from this all fish may be cooked by any of the traditional methods of poaching, boiling, shallow frying and so on. Large fish, whatever their category (but again there are exceptions), are cut into portion sizes before cooking. This provides not only an effective means of controlling the number of portions and the amount of waste but also helps the preparation and avoids problems such as drying out during cooking. For example, whilst it is possible to grill or shallow fry a whole turbot weighing 2 kg, because of its thickness doing so would in all probability make it dry and therefore inedible once cooked.

All fish should be washed in cold water and dried before handling for cooking.

Preparation of whole round fish

Examples of whole round fish to be prepared in the following manner are herring, salmon and trout.
(1) Remove the scales by scraping them with a knife, working from tail to head.
(2) Remove all fins using a pair of scissors.
(3) Make an opening from the vent to the belly and remove all the gut with either the fingers or the handle of a fork.
(4) If the head is to be left on remove the gills gently with a small knife from the opening alongside the gills. Remove the eyes with the pointed end of a peeler. Care should be taken not to break the connective skin joining the underpart of the head to the body.
(5) If the head is to be removed then cut an inverted V-shaped incision each side of the head just below the gills.
(6) Make two very shallow incisions on each side of the fish just penetrating the skin at the thickest part – this is to facilitate cooking.

Preparation of Dover sole:

Sole cannot be skinned in the same way as other fiat fish. This method should be followed before filleting.
(1) Remove all fins using a pair of scissors.
(2) Remove the skin commencing at the tail end; make a slight incision across the centre of the tail, scrape backwards and forwards until the skin begins to lift, then take the loosened skin between the fingers and separate it from the fish by pulling upwards and away. It may be helpful to hold the skin in a cloth to prevent it slipping.
(3) Remove the head by cutting at an angle following the direction of the natural shape of the head formation.
(4) Remove the gut and roe by pushing with the fingers along the external area, or use a knife.

Preparation of other flat fish:

Flat fish other than sole such as turbot, halibut and plaice are prepared in this way.
(1) Remove the fins by cutting through them close to the body of the fish but against the natural formation.
(2) Remove the gills and scales.
(3) Remove the head by cutting along the natural line and following the shape of the head.
(4) Remove the gut and roe by cutting an opening just under the head; scrape clean and remove all traces of blood and gut that may adhere to the bone.

To fillet flat fish

(1) Make an incision down the length of the fish following the natural line of the backbone and working from head to tail.
(2) With a flexible knife cut down against the bone structure allowing the bone formation to direct the flat side of the knife. With a clean sweeping motion cut from the center of the fish to the fins. Remove the fillet and repeat this action until all four fillets have been removed.

To fillet round fish:

(1) Commence by cutting a deep incision along the backbone of the fish.
(2) Continue cutting with the flat of the knife following the natural formation of the rib bones until the fillet comes free. Repeat on the other side.

Removal of skin from fillets

(1) Place the fillets on a work surface skin side down and with the tail end towards you. Gently cut and lift the fish from the extreme tail end then commence cutting downwards and pulling back the skin with the fingers.
(2) Fillets and suprêmes once skinned should be lightly flattened by dipping them in cold water and gently beating them with a butcher’s bat.
(3) Two small incisions should be made in the surface of the fish on the skin side before cooking.