The swordfish is one of the most extraordinary fishes in the sea. One of the largest, fastest and most aggressive of all bony fishes, it starts its life at the size of a grain of rice and can reach over a thousand pounds. The function of its sword, which is a third the length of its body and sometimes impales boats, is unknown. Found around the world, traditionally often caught by means of a harpoon like a whale, the swordfish has been the fish of legends for millennia. But is it kosher?
In Orthodox circles today, it is widely believed that the swordfish is unequivocally non-kosher, and has only ever been eaten by Conservative Jews. Yet this is a myth. In 1933, a list of kosher fish published by none other than Agudas HaRabbonim—the premier right-wing Orthodox rabbinic organization of the early twentieth century, under the leadership of Rav Eliezer Silver—included swordfish! And the following year, under the leadership of Rav Yosef Kanowitz, the list was reprinted, still with swordfish—even though other fish had been removed from the list, after criticism from detractors.
Rabbi Dr. Ari Z. Zivotofsky, in “The Turning of the Tide; The Kashrut Tale of the Swordfish” (BDD 19, January 2008), has thoroughly documented how traditionally, the swordfish was considered to be kosher, and how this changed in the latter half of the 20th century. While the rejection of the historical tradition was understandable, there are strong grounds for justifying the tradition.
The Talmud and Tosefta mention a fish called achsaftias as being kosher. The word achsaftias is not Hebrew or Aramaic—as Rabbeinu Chananel notes, it is an Aramaicized version of a Greek word. This is the Greek word ξιφίας xiphias, which refers to the swordfish (based on the Greek ξίφος, xiphos, which refers to a sword).  From the outset, then, the swordfish would appear to be the achsaftias of the Talmud, described as a kosher fish.
The swordfish, Xiphius gladius, is one of a group of large predatory fishes with swordlike projections known as billfish. Other billfish are several species of marlin, sailfish, and spearfish (which has a relatively short bill). Two of the ways in which swordfish differ from other billfish are of great significance. One is that whereas the bills of other billfish are round in cross-section, like a spear, that of a swordfish is flat in cross-section, like a sword. Accordingly, any reference to a fish named “sword” presumably refers to the swordfish.
The second, no less significant, specific characteristic of the swordfish is that it is by far the most common of all billfish species in the Mediterranean. If the swordfish were to be a non-kosher species, then the Talmud would not describe another billfish as being kosher, and mislead people into thinking that it was talking about the more common swordfish.
The Talmud presents the achsaftias as an example of a fish that is kosher even though it does not have scales. The reason that it gives is that this fish is born with scales, but sheds them when it is taken out of the water. Now, swordfish are not known to do this. However, no other billfish is known to do this either. Furthermore, we must assess what the Talmud is stating based on fact, and what is being stated based on presumption. The fact would be that the achsaftias is a fish without scales. Another fact would be that it is known to be kosher. And a presumption would be that it lost its scales when taken out of the water. In fact, as we shall see, there is another explanation why the swordfish appears to have lost its scales. But there is every reason to believe that it is the fish being discussed in the Talmud—and no other viable candidate.
The next significant discussion about the swordfish is found in the writings of the renowned 17th century halachic authority from Turkey, Rabbi Chaim ben Yisrael Benvenisti, known as the Knesset HaGedolah. He writes as follows:
“It is a widespread custom among all Jews to eat the fish with the sword, known in vernacular as fishei espada, even though it does not have any scales. Because it is said that when it comes out of the water, due to its anger, it shakes and throws off its scales.”
This statement is cited as authoritative, without dispute, by a number of prominent authorities, including Pri Megadim, Darchei Teshuva, Chida, Kaf HaChaim, and others. There is furthermore clear testimony that swordfish was eaten in many communities, under rabbinic approval. And, as noted earlier, the swordfish was rated as kosher by leading halachic bodies in the early twentieth century. In fact, it seems that before the 1950s, nobody at all questioned its kosher status.
The situation changed in 1951, when Rabbi Dr. Moshe Tendler examined a swordfish and did not find any scales. He became convinced that this was not a kosher fish, and furthermore that it could not be the fish described by the Knesset HaGedolah. Rabbi Tendler therefore launched a campaign against the consumption of the swordfish. While there was a heated response from Rabbi Isser Yehudah Unterman (then chief rabbi of Tel Aviv), Rabbi Eliezer Waldenberg took the side of Rabbi Tendler. A fierce debate erupted in halachic journals during the 1960s, though unfortunately all sides suffered from a lack of accurate information regarding swordfish and other billfish.
Meanwhile, the Conservative movement issued a ruling that the swordfish was kosher. Rabbi Tendler subsequently published an article in The Jewish Observer describing the situation as a dispute between Orthodox and Conservative Jews—and thus naturally the rest of the Orthodox community decided to take his side.
However, it is abundantly clear that the Knesset HaGedolah was indeed referring to swordfish. The name for it that he uses, fishei espada, is the name of the swordfish in numerous Mediterranean countries. Rabbi Tendler argues that he was referring to sailfish—but these are rarely found in the Mediterranean, and the Knesset HaGedolah speaks about a commonly found fish. And, as noted earlier, since people in that region were widely eating swordfish—the most common billfish—it is inconceivable that the Knesset HaGedolah would refer to a different fish and not mention any problem with the swordfish.
We have seen that there is a widely supported ruling from the Knesset HaGedolah that the swordfish is a kosher fish, which seems to go back as far as the Talmud, together with longstanding testimony that it was commonly eaten. In light of that, we should seek to validate this ruling and practice—there is a halachic principle that we seek to avoid casting aspersions on earlier generations. Still, if there were no solid grounds for us to independently permit swordfish, this would put us in a difficult position, and we would have to refrain from eating it. Nevertheless, this
is a case where the longstanding halachic position and general practice can be independently justified. Juvenile swordfish, until around four feet in length, are seen to possess scales, in two varieties—smaller ones with a single spine emerging from them, and larger ones with several spines. 
Contrary to ancient belief, the apparent absence of these scales in adults is not because they are all shed when it is removed from the water—as noted, there is no fish that does this. Rather, it is because by the time the swordfish reaches adulthood, its skin has thickened around the scales, such that they are barely, if at all, detectable.  (Note the swordfish is the only billfish in which this happens. With all other billfish, the situation is exactly the opposite of that described by the Talmud and Knesset HaGedola—they lack scales as juveniles, but develop them as they mature. Thus, this is further evidence that the other billfish could not be the fish described by the Talmud and Knesset HaGedola.)
If a fish has scales as a juvenile, but lacks them as an adult, is it a kosher fish? The Talmud only discusses the kashrut of fish which gain scales as an adult, and which lose them as a result of being removed from the ocean, not the kashrut of fish whose scales naturally change into an unacceptable variety. However, Aruch HaShulchan (YD 83:16) states that the Talmud’s dual permissions to eat fish that later grow scales and fish which lose their scales when removed from the sea serve to signify that scales need only be a feature of the species, not of any individual fish at any given time.
Furthermore, there is a simple logical reason why a fish that starts life with appropriate scales must always be rated as kosher. Jewish law allows one to eat a fish based on the presence of fins and scales, even if one does not know the species. But if the subsequent loss of scales would mean that the fish is not kosher, then how could one ever rely on the current presence of scales to be sure that the fish is kosher? It must be that just as a fish which later grows scales is kosher, so too a fish that has scales early in life is kosher.
Yet do the scales of swordfish qualify as kosher scales? Ramban states that scales must be detachable, and notwithstanding the apparent lack of basis for this in the Torah or Talmud, it has been universally accepted as a halachic requirement. Do the scales of swordfish satisfy this requirement?
Swordfish scales are attached to the lower layer of the dermis along their entire base. They are thus more comprehensively attached than are the scales of other fish such as carp. However, there are other kosher fish, such as perch, sea bass, sheepshead and grouper, which likewise have scales that are relatively strongly attached. (Note that no less an authority than the Noda B’Yehuda rated even the scales of sturgeon as being acceptable.) Rabbi Tzvi Hirsch Shapira (Darchei Teshuvah 83:10-11 and especially 83:13) stresses that scales are valid even if they are attached all the way around their base, and even if they can only be detached with a utensil and with effort, and even if there is skin above them, as long as there is also skin beneath them; Aruch HaShulchan writes similarly. With swordfish, the entirety of the stratum compactum (the lower layer of the dermis) lies beneath the scale.
A contemporary practical examination of the swordfish has been conducted by Rav Shlomo Machpud of Bnei Brak, one of the most respected authorities on kashrut today, in the presence of several other kashrus experts. He wrote that he performed a careful examination and found numerous scales that were easily detachable. Rav Hershel Shechter has likewise stated in several forums that the swordfish is kosher, and attested that this was also the view of Rav Soloveitchik (although others dispute this). Rav Avraham Yosef reports that his father Rav Ovadiah Yosef permitted swordfish. The Chief Rabbi of Montreal, Rabbi Daavid Sabbah, has stated that he personally inspected juvenile swordfish in Tangiers and found easily detachable scales.
A case could perhaps still be made against swordfish as follows: that the scales described in scientific literature are too deeply embedded to be considered halachically acceptable, and that the detachable scales found by Rav Machpud and others were all the result of contamination from other fish. Still, there is certainly ample justification for those who consider the swordfish to possess acceptable scales, and who welcome a contemporary halachic ruling which confirms the longstanding tradition.
To summarize: the Talmud refers to a fish called achsaphtias which is kosher even without scales, due to its having formerly possessed them; there is every reason to believe that it is referring to the xiphias, swordfish. This is all the more true for the Knesset HaGedolah, which further describes it with the common name for the swordfish and notes that it is widely consumed—there is no other fish that it could be referring to. Finally, the swordfish is indeed found to have scales, which disappear from view as it matures, and while the halachic validity of these scales might be questioned, several contemporary halachic authorities have ruled that they found acceptable scales and that the swordfish is kosher.
Consuming swordfish today, however, is challenging for the religious Jew. The reason is that it is only adult swordfish which are caught in the fishing industry, and they are enormous. Due to the impracticality of transporting and selling a thousand-pound fish to the retail market, fishmongers instead buy loins and steaks. Now, whereas the steak of a fish such as tuna can be purchased by the kosher consumer, since the scales are visible, there are no scales on an adult swordfish. So while the swordfish is kosher, the problem is how one can be sure that the chunk of fish at the
market is really from a swordfish? In fact, shark is sometimes marketed as swordfish!
In theory it is possible to identify swordfish by the unique pattern of whorls in the flesh, but there does not appear to be a rabbinic authority who is willing to rely on this. Thus, the only way to eat swordfish is to obtain the entire fish, so that one can be sure that it really is swordfish. Since a whole swordfish is rather difficult to transport and can cost well over a thousand dollars, this makes it difficult for the kosher consumer to obtain it.
Accordingly, acquiring swordfish for the Feast of Legends from the Sea at the Biblical Museum of Natural History posed quite a challenge. To make things even more difficult, swordfish have been overfished in the Mediterranean and are now much less commonly found. It took months of calling various fishermen until we finally struck gold, with a fisherman based out of Ashdod who had caught a swordfish around six feet long. The price: three thousand shekels! Then there was the difficult of finding a walk-in freezer big enough to store it. But all this effort was worth it,
for this special experience in halachic history.
Talmud, Chullin 66b and Tosefta Chullin 3:27.
See Samuel Krauss, Griechische und Lateinische Lehnwörter in Talmud, Midrasch und Targum (1899) vol. II p. 49 and 294.
Giovanni Bearzi, Elena Politi, Stefano Agazzi, & Arianna Azzellino, “Prey depletion caused by overfishing and the decline of marine megafauna in the eastern Ionian Sea coastal waters (central
Mediterranean),” Biological Conservation 127 (2006) pp. 373-382.
Thomas Potthoff and Sharon Kelley, “Development of the vertebral column, fins and fin supports, branchiostegal rays, and squamation in the swordfish, Xiphias gladius,” US Fishery Bulletin 80 (1982) pp. 161-186; G.F. Arata Jr., “A contribution to the life history of the swordfish, Xiphias gladius Linnaeus, from the South Atlantic coast of the United States and the Gulf of Mexico,” Bulletin of Marine Science 4:3 (1954) pp. 183-243.
J. J. Govoni, M. A. West, D. Zivotofsky, A. Z. Zivotofsky, P. R. Bowser, and B. B. Collette, “Ontogeny of Squamation in Swordfish, Xiphias gladius,” Copeia, 2004(2):391-396.