As long as humanity has sought sustenance, there has been fish to provide it. Whether for an informal lunch or an elaborate dinner, it is inconceivable that a menu would not include fish. However, not all types of fish may be enjoyed by the kosher consumer. Many varieties of fish are prohibited medoraisa. Moreover, there are numerous issues regarding the processing of fish that could impact the kosher consumer.
A kosher fish must posses several characteristics. All kosher fish must posses snapir vekaskeses (fins and scales). Furthermore, the scales must be capable of being removed without tearing the fish’s skin (See Rema Yoreh Deah 83:1). It is not unusual for some fish to meet the first two criteria and not the third. Sturgeon, which is a very common type of fish, is a prime example. Although sturgeon does posses simanim, the scales are embedded and cannot be removed without tearing the skin.
There are a number of interesting issues regarding the fish industry and the practical halacha. Not all types of fish are found uniformly throughout the world, and fishermen will only find certain types of fish in specific areas. Nevertheless, it is standard that every fisherman’s net catches a small amount of “secondary” fish varieties in addition to the main catch. The “incidental fish” are known in the industry as by-catch. The by-catch is typically incompatible with the primary catch. There are times when non-kosher fish might be mixed in the same nets as a kosher variety. It is standard practice throughout the fish industry that the catch is rigorously hand sorted several times to remove all foreign fish from the main catch. The hand sorting is intended to ensure that only the desired variety of fish is brought to the plant before the processing begins. Nonetheless, some poskim take the position that a mashgiach temidi must be present at the time of the entire processing, to confirm that non-kosher varieties of fish do not enter the manufacturing facility (see Kisvei Rav Henkin Teshuvos Ibra, 38:2 ). The Beis Yosef (Yoreh Deah 83) quotes the Tosfos Rid who maintains that when there is a bona-fide chazaka that a fisherman deals exclusively with a kosher variety of fish, it is permissible to purchase fish from that source, even without simanim (See Mesorah Volume I, pp. 79). Some poskim maintain that the several meticulous hand sorting processes create a chazaka which ensures that all by-catch is removed (ibid, pp. 69 ). The removal of the skin and gutting of the fish occur at the plant. Fish which are typically eaten raw, such as anchovies, may sit in brined barrels for several months before they are placed in jars and sold. Most other types of fish are cooked before they are canned, and they are shipped out almost immediately after the processing. An astute mashgiach must ensure that the sensitive aspects of the production are properly supervised to meet acceptable kashrus standards.
Rav Moshe Feinstein zt’l writes against identifying skinned fish with a mere tevias ayin (familiar eye). Fish must posses simanim, or an identifying characteristic to confirm that it is from a kosher variety (See Igros Moshe Yoreh Deah 3:8). There are a few types of kosher fish whose flesh are a unique color and could serve as a proper siman, assuming the color could not be possibly duplicated in a non-kosher variety. Salmon is a good example of this kind of fish. The distinctive pinkish-reddish color shade of salmon distinguishes it from other types of fish. Farmed salmon whose flesh color might lack the appropriate pinkish-redness shade are fed dietary supplements of astaxanthin, an anti-oxidant that is from the same family as beta-carotene. (Beta-carotene is an anti-oxidant naturally found in carrots and sweet potatoes), to enhance their flesh color to resemble the pinkish-red shade of wild salmon. Excess carotenes are stored in the flesh of salmon, as opposed to other creatures who might store excess levels of the ant-oxidant in their skin. This same practice could not be successfully employed to alter the flesh color of other types of fish to resemble salmon, and there are no known documented cases of duplicating the salmon’s pinkish-reddish shade in other fish varieties. Consequently, there are poskim who accept salmon fillets without snapir vekaskeses because the distinct color serves as a suitable siman. However, this principle would not apply to kosher caviar eggs that are very often dyed to resemble non-kosher caviar. The Shach (Yoreh Deah 83:27) quotes a custom from the Beis Yosef of identifying caviar eggs as kosher if they have a unique color. Nevertheless, on the retail level, caviar eggs purchased by consumers today are usually dyed and the color would not serve as an acceptable siman.
Bishul akum is another fascinating topic which has been discussed with regards to the fish industry. The two criteria for a cooked item to be considered bishul akum is that it is not eaten raw, and is fit to be served at a king’s table (see Avodah Zarah 38a). Although sushi has become increasingly proper, it is still difficult to categorize fish as a food that is eaten raw. Furthermore, it is not uncommon to find fish on the menus of fancy restaurants and caterers. Fish very often will require bishul yisroel unless neither of the two basic requirements applies. For example, many assume that sardines do not require bishul yisroel since they are not oleh al shulchan melachim.
There are also some poskim that are lenient with regards to bishul akum when the food is cooked with steam in a factory (See Minchas Yitzchok 3:26), which is the case with sardines. Tuna is a type of fish that might require bishul yisroel depending upon how it is prepared. Canned tuna is cooked twice while it is processed at the factory. It is first steamed with the skin on prior to removal, and after canning in an industrial cooker. Although tuna is often broiled or grilled and served at fancy restaurants, the taste of the tuna after the first steaming in a factory is poorer in quality than the final canned product. Canned tuna is also not a variety that is considered a fancy grade which qualifies as oleh al shulchan melachim according to many poskim. However, poskim who are stringent with regards to steam in factories, or define oleh al shulchan melachim not by the final product but by the type of fish, would require a mashgiach to be actively involved in the cooking process.
The issue of bishul akum is very prevalent to salmon. Salmon is a popular kosher fish, which is generally not eaten raw in its natural state and can certainly find its way on to the table of a fancy dinner. Salmon is commonly found in the form of lox, nova, or the hot smoked variety. Lox and nova are prepared by brining salmon is a saltwater solution, which might also include sugar. The fish is placed in a smoking oven at a temperature below 100 degrees, where smoked flavor is added to the fish. This process is known as cold smoking. Lox and nova are technically not cooked, and therefore there is no concern of bishul akum. However, hot smoked salmon is cooked at hot temperatures, and would require bishul yisroel. In some instances, hot smoked salmon is prepared by taking lox or nova and hot smoking it. Under these circumstances, since the fish is edible prior to the cooking there is no need for bishul yisroel.
Questions have been raised about the presence of tolaim (insects) in fish. This issues tends not to be very problematic on a practical level. Fish feed off of various organisms found in their natural habitat. In some instances, kosher fish may get its nourishment from non-kosher organisms. Although non-kosher seafood and tolaim found in the stomachs of kosher fish are prohibited (See Shulchan Aruch Yoreh Deah 83:10), the stomachs of the fish are removed when they are processed. Tolaim found in the flesh of the fish, or between the skin and flesh of the fish are permitted. Tolaim found in these areas are born inside the fish, and do not have the prohibited status of sheretz hayam (Shulchan Aruch Yoreh Deah 84:16, Shach 43).
There are many intricate halachic issues today with regards to the fish industry. It is important that consumers are properly educated with regards to the actual practices of fish companies, and how they are viewed through the eyes of the halacha. Since there are differences of opinion with regards to application of the halacha to many of these questions, consumers should not hesitate to consult their local Rov for proper guidance.