Fish smoking is a method which should be used more extensively in home food preservation of fishery products, says the U.S. Fish and Wildlife Service. When the curing is properly done, it is inexpensive and the product is of high quality, attractive in appearance and taste. Although preservation by smoking usually lasts for a shorter time than by salting, the product is more appetising. If smoked fish spoils quickly and is poor in quality, it is as the smoking has been done improperly. If proper attention is given to materials and methods, little difficulty should be experienced. The efficiency of smoking depends on the drying action; it is only a flavouring and colouring agent. According to species, fish may be smoked either in the round, gutted, split and beheaded, or cut into pieces with or without the skin removed. There are two general methods of smoking fish: hot-smoking or barbequing - and cold-smoking. In hot-smoking, the fish are hung near the fire, usually not more than 3 or 4 feet distant - and smoked at temperatures from 150 to 200F so that they are partially or wholly cooked. Therefore, while hot-smoked fish is very appetising and requires no preparation, it will keep for only a short time. In cold-smoking, the fish are hung at some distance from a low smouldering fire and smoked at temperatures usually lower than 90F (a temperature of 90F may be used occasionally). The degree of preservation depends on the length of time the fish are smoked; fish cold-smoked a few hours, for example, will keep only a short time. If an extended period of preservation is desired, fish must be cold-smoked from a few days to a week or more. The same general principles governing the smoking, handling and storing of cured meats should be followed with fish. Hot-Smoking. Almost any species may be hot-smoked. Mullet, shad, Spanish mackerel, mackerel, alewives or river herring, herring, lake herring, whitefish and king mackerel. This method is recommended if it is desired to prepare a fish that can be used immediately without cooking. Fish smoked by this method may be kept longer without molding or souring, but even so, it will preserve for only a short time. Split the fish along the back, just above the backbone so that it will be open in one piece, leaving the belly solid. Scrape out all viscera, blood and membrane. Make an additional cut under the backbone for the smaller fish. For the larger fish, cut out the forward three-fifths of the backbone. Wash thoroughly and soak in a 70 salt brine (1/2 cup salt to 1 quart water) for 30 minutes to leach blood out of the flesh. Then prepare a brine, using the following ingredients: 2 pounds salt, 1 ounce saltpetre, 1 ounce crushed black peppercorns, 1 ounce crushed bay leaves. This makes a 90 per cent brine (saturated salt solution). The amounts of ingredients are increased in proportion to the amount of brine to be made. The spices used may be increased both in variety and quantity. The fish are held in this brine for periods varying from 2 to 4 hours, depending upon their size and thickness, amount of fat and the desire for a light or heavily cured fish. Weather conditions also make a difference; the exact length of time must be determined by experiment. Rinse off the fish in fresh water and hang outside in a cool, shady and breezy place to dry for about 3 hours before hanging in the smokehouse, or until a thin shiny "skin" or pellicle has formed on the surface. For the first 8 hours that the fish are in the smokehouse, the fire is low and smouldering. The temperature should not be higher than 90F. A dense smoke should then be built up. After 4 hours of heavy smoking, the fire is increased until the temperature is between 130 and 150F. The fish are cured at this temperature for 2 to 3 hours, or until they have a glossy, brown surface. This partially cooks, or hot-smokes, the fish. When smoking is finished, the fish must be cooled for 2 or 3 hours. They may be brushed over lightly with vegetable oil (usually cottonseed) while warm. This is sometimes done just after finishing the cold-smoking part of the process. The oil forms a light protective coating, but the chief value of this treatment is to make the appearance more attractive. Another method is to dip the fish in melted paraffin; thus, a more effective protective coating is formed, but the fish must be handled carefully as the coating is brittle. The paraffin must be peeled off when preparing the fish for the table. Each fish should be wrapped in waxed paper and stored in a cool, dry place. Spoilage occurs more rapidly if the fish are stored in a warm place or under damp and cold conditions. Cold-Smoking. Small fish, such as sea herring, alewives (river herring), spots, or butter fish may be cold-smoked in the round (without cleaning), but they should be gibbed. Gibbing consists of making a small cut just below the gills and pulling out the gills, heart and liver - leaving the belly uncut. Fish larger than one pound should be split along the back to lie flat in a single piece, leaving the belly portion uncut. All traces of blood, black skin, and viscera must be removed, paying special attention to the area just under the backbone. The head does not need to be removed. If the head is cut off, the hard bony plate just below the gills is allowed to remain, as it will be needed to carry the weight when the fish are in the smokehouse. Next wash the fish thoroughly, whether gibbed or split - and place them in a brine made in the proportion of 1 cup of salt to 1 gallon of water. They should be left in the brine at least 30 minutes to soak out blood diffused through the flesh. At the end of this time rinse in fresh water to remove surplus moisture and drain for a few minutes. Each fish is dropped singley into a shallow box of fine salt and dredged thoroughly. The fish is picked up with as much salt as will cling to it and packed in even layers in a box or tub. A small amount of salt may be scattered between each layer. The fish are left in salt from 1 to 12 hours, depending upon the weather, size of fish, fatness, length of time for which preservation is desired and whether the fish are round or split. When the fish are taken out of the salt, they should be rinsed thoroughly. All visible particles of salt or other waste should be scrubbed off. They are hung to dry in the shade as in dry-salting of fish. An electric fan may be used if there is not enough breeze. The chicken-wire drying racks used in dry-salting may be utilised if they are not exposed to direct sunlight. The fish will dry on both sides but the impression of the chicken wire detracts from its appearance. The fish is dried until a thin skin or pellicle, is formed on the surface. This should take about 3 hours under average conditions. If smoking is begun while the fish are still moist, the time required is longer, the colour will not be as desirable, the fish will not have as good a surface - and will steam and soften in smoking. Start a low, smouldering fire an hour or two before the fish are hung in the smokehouse. It must not give off too much smoke during the first 8 or 12 hours if the entire cure is 24 hours, or for the first 24 hours if the cure is longer. The temperature in the smokehouse should not be higher than 90F in California or the southern states, or 70F in the northern states. If available, a thermometer should be used in controlling smokehouse temperature; if not, a rule-of-thumb test is to insert a hand in the smokehouse and if the air feels distinctly warm, the temperature is too high. At the end of the first smoking process, a dense smoke may be built up and maintained for the balance of the cure. If the fish are to be kept for 2 weeks, they should be smoked for 24 hours, or for a longer time. Smoking may require 5 days or even more. Hardsmoked or red herring may require 3 or 4 weeks. Keep the fire low and steady; if hardwood sawdust is not available, use chips and bark - they serve almost as well. Rice husks and corncobs can be used. The fire must not be allowed to die out at night. Do not build it up before leaving, as this will create too much heat. It must be tended regularly during the night. Here is the best way to smoke fillets. Any white-fleshed, "lean" fish will produce fillets weighing more than 1 pound which are satisfactory for smoking. Cut the fish into fillets, removing the backbone and skin. Cover with a 90 brine (saturated salt solution) and hold for 2 hours. Remove and drain for 10 to 15 minutes and air-dry for 2 hours. Hang across a threesided smokestick, each side about 3 inches in width. Smoke over a fire with a fairly light smoke for 4 hours at a temperature not higher than 90F. Turn the fillets so that the side resting on the smokestick is uppermost and smoke 4 hours longer. Smother the fire so that a dense cloud of smoke is produced and smoke until the fillets are a deep straw yellow, turning the fillets once or twice so that both sides will be evenly coloured.