Anybody who observes laws of kashrut knows that fins and scales are the signs of a kosher fish. In today’s daf TB Khullin 66 we learn that scales don’t have to be a permanent feature of the fish to be kosher. “§ The mishna states: And with regard to fish, any fish that has a fin and a scale is kosher. The Sages taught in a baraita: If a fish does not have scales now but will grow them after a period of time, such as the sultanit and afyan fish, it is permitted. Likewise, if it has scales now but will shed them when it is caught and rises from the water, such as the akunas, and the afunas, and the kesaftiyas, and the akhsaftiyas, and the atunas, it is permitted.”(Sefaria.org translation)
Is a swordfish kosher? Rabbi Isaac Klein writes:
“In the Talmudic Encyclopedia, under the article ‘Daggim,’ this swordfish is identified as Xiphias gladius, a fish which, in its early stages, has scales that disappear when it matures. According to its Latin and Greek names it is suggested that it is the Akseptias of the Talmud: Hulin 66b (Talmudic Encyclopedia, vol V, pp. 207ff)
“Well there has been some question about this, one of the later authorities whose opinions have been widely accepted says unquestionably:
It
is the widespread custom in all Israel to eat this swordfish called “fish
ispada”
even though it has no scales because it is said that when it comes out of the sea, because of his excitement it shakes and sheds its scales (Darkei Teshuva 83:16).
“Similarly, Rabbi H. P. Tchorch of the Israel Ministry of religion in a report about kashrut in Israel discusses the swordfish, and after quoting a number of authorities concludes:
“From all the above it becomes clear that swordfish is permitted.”
“Then comes the following:
“However,
a great scientist, and one the experts in identifying fish (ichthyologist),
Rabbi Moshe Tendler, a professor at the Yeshiva University in New York,
disagrees with the manner of classifying this fish. According to him, it
becomes clear that there are two classes of fish called swordfish [sailfish and
swordfish}. The first is the “clean” fish, but the second is an “unclean” fish.
It is then possible to say that the author of Knesset
Hagadolah who permitted the fish ispada, meant the latter, which is called “sailfish” (Sinai, v. 32, issues 4-5, p. 209)
“Evidently this noted scientist and expert ichthyologist has so over awed all his colleagues in the Orthodox rabbinate, that even those who had permitted it, backtracked. In Israel they concluded that the matter needs further study.”
Rabbi Klein sought out experts in the field to ascertain whether the immature swordfish has scales are not. He turned to Dr. Carl Gans who holds a PhD in zoology to write a letter to Mr. Bruce B. Collette of the Bureau of Fisheries of the United States Department of the Interior. Mr. Colette is an expert one can rely upon. The following answer came:
Dear
Carl:
In
reply to your letter of December 7 on the swordfish-scale problem, enclosed is
a Fishery Leaflet by Isaac Ginsberg on the subject and also a xerox copy of the
Nakamura
et
al. paper of 1951. As you can see from these references, swordfish do have
scales as juveniles. They retain the scales until they are approximately four
feet long. This means
that
most swordfish found in the markets no longer have scales although they once
did. Whether this leaves it kosher or not is up to your rabbinical friend.
Sincerely,
Bruce
B Colette
Assistant Laboratory Director
Rabbi Klein concludes: “… In the government List of Common Food Fishes that Have Both Fish and Scales, the swordfish is listed too. On the basis of this evidence, we have to reconfirm our original position that the swordfish is kosher. (My emphasis )”
For the entire teshuva see Responsa
and Halakhic Studies by Isaac Klein, Ktav Publishing house: New York, 1975,
pages 75-78.