Gedolei Yisroel, including Maran HaRav Yosef Sholom Eliashiv, shlita, are publicizing a halachic ruling this week regarding a type of worm known as Anisakis found in certain fish. It was originally issued over a year ago.
After thoroughly investigating the matter, all of the major poskim have backed a resolute ruling that Anisakis, a species of nematode (roundworm) found in the intestines and flesh of fish, are strictly forbidden by Torah law.
The psak has been published now, in response to the problem which has arisen in recent years as it became known that Anisakis are found in the abdomen of fish and not just in the flesh. Worms that form in the flesh of fish do not pose a problem, unlike worms that came from outside sources. (This matter was clarified by the leading poskim of the previous generation, and is not the subject of this report.)
As a result, it became apparent that the worms in the intestines of the fish might be prohibited because they come from outside the fish. In the meantime, other evidence came to light indicating that the worms found in the flesh of the fish also come from the intestines and from outside the fish. Following extensive discussion and clarification, top poskim, including HaRav Eliashiv, ruled that consuming these worms is prohibited by the Torah.
The problem occurs in the case of saltwater fish which grew in polluted waters where biological conditions can sustain the Anisakis nematode. In fish ponds the problem does not exist. Likewise, salmon from Norway and Chile do not pose a problem since they are raised in caged areas at sea where the marine species that normally transmit the worm are not present. Sole from Holland are also generally free of this problem due to the manner in which the fish are raised and collected. Nile perch are completely free of worms.
Anisakis infestation is not a problem in fish raised in Eretz Yisroel, such as carp (karpion), silver carp (kassif) and mullet (buri), since they are grown in fish ponds, but proper kashrus supervision is required to ensure that other external parasites are not present. Likewise canned tuna does not contain these worms. Prepared herring fillets imported from Norway with good kashrus supervision are considered worm-free and are subjected to a number of inspections. Whole herring that has not been gutted is considered infested.
Some of the problematic fish, such as sole, can be cleaned to remove the worms, but this requires great expertise and care. Others, such as salmon, cannot be cleaned of these worms because of the color of the flesh and the large number of worms.
Some young codfish (bakala), even sold under kashrus lemehadrin, are full of intestinal worms, which are forbidden by Torah law for consumption.
A psak halacha on Anisakis in fish originally written by HaRav Moshe Shoul Klein, was also signed by HaRav Eliashiv, HaRav Shmuel Halevi Wosner, HaRav Nissim Karelitz, HaRav Chaim Kanievsky, HaRav Shmuel Auerbach, HaRav Moshe Shternbuch and HaRav Nosson Gestetner. Several rabbonim added comments along with their signatures. For example, HaRav Auerbach noted that some people are circulating inaccurate rumors that his late father zt"l would have permitted these worms.
Due to various inaccurate rumors circulating recently regarding the opinion of gedolei Yisroel, they made a special effort to issue a clear halachic ruling.
The rabbonim also note that although these fish have been forbidden by gedolei Yisroel, certain kashrus organizations label them kosher lemehadrin and even write that they have been checked for worms. Just last week dozens of worms were found in salmon certified by one of these kashrus organizations.
Click here for a Hebrew Chart of fish commonly sold in Israel.
Click here for a copy of the original letter.
