Q: My local fish store does not have kosher supervision and mostly sells fish with the skin already removed. The names of the fish are kosher sounding. Is there any problem with me buying fish from this source?
A: It is forbidden to purchase fish without skin, unless the skin was removed under kosher supervision. The reason for this requirement is that when one removes the skin of a fish, it is impossible to know what species it is. The name on the label is meaningless, because of an issue known in industry as species substitution. This is when an unscrupulous seller (or importer, or distributor, etc.) mislabels a cheap product with the name of more expensive species for financial benefit. Recent news stories have highlighted this practice with regards to a fish called basa or tra. In order to avoid import duties, many have taken to labeling and selling this non-kosher catfish as “grouper” (a kosher fish). If someone purchased skinless “grouper,” for example, it is quite possible that what they really bought was a non-kosher fish. In fact, grouper and basa look nothing alike, and one would imagine that the purchasers of this falsely labeled product would immediately realize the folly being perpetrated on them.
One must check the fish he is buying for the presence of scales, which can be removed from the fish without ripping the skin (all such fish have fins, so there is no need to check). If the fish was already descaled, but one can recognize it by looking at the skin, this is permitted as a valid form of identification as well.
Q: I heard that some people bring a knife from home to the fish store, because the one they use in the store might have residue from non-kosher fish on it. Is this true, and what should I do if I don’t have a knife to bring?
A: Yes, there is a concern that the non-certified store uses their knives on non-kosher fish (even when they claim to have a “kosher” knife only used on kosher fish). You can bring a knife from home to avoid this concern, but there is another option: you can have the store wash their knife and check to make sure it is truly clean (and not just “sort of rinsed”). The board the fish is cut on must be properly washed as well, or covered with craft paper, to protect the kosher order from being compromised by residue left on the board from a previous, non-kosher, order.
Q: What about salmon? Is it true that the OU endorses buying salmon without skin and without a hashgachah?
A: Yes, the OU has researched various questions which have been presented over the years about the kashrut of salmon, and we still endorse the idea of buying skinless salmon. So long as the consumer is familiar with what salmon is supposed to look like, we are not concerned that another fish will be substituted for salmon which is not kosher. There are other fish which look very similar to salmon (some types of trout, arctic charr, etc.), but they are all kosher. We are not aware of any non-kosher fish which looks like salmon, and OU policy assumes that the red color is considered an acceptable indentifying mark for kosher. As such, the OU allows for salmon to be purchased without skin.
Q: What about the knives used in salmon processing plants, and how does that differ from the obligation to bring a knife to my own local (non-certified) fish store?
A: The factories which produce both wild and farmed salmon produce copious amount of fish every day, and even if there was a non-kosher product cut with the same knife, the non-kosher residue on the knife would be wiped off on the first few pieces of fish cut with that knife. Those fish would be mixed in with thousands (or tens of thousands) of other salmon, which would be perfectly clean of residue, and become nullified (batul). The Shulchan Aruch (YD 96:4) rules in the case of lemonade and salted fish that all of the product is permitted, despite the non-kosher knives involved. The Rama explains that this is due to the large amount of product cut with the same knife.
In the case of the local fish store, the seller likely does not cut such large amounts of the same product at a time. One needs to be concerned that the same knife is used for both kosher and non-kosher (or skinless) fish, and therefore needs the knife (and cutting board) to be kosher. If one does not bring his own knife and board, he may ask the store to wash theirs, and confirm that they are clean before the store cuts up the kosher order. If one forgot to check the cleanliness of the store’s knife and board, or if one is afraid they were not properly cleaned, all is not lost! Simply wash the fish off, and scrape the surface of the fish with the sharp side of a knife to remove the residue which might remain on the fish, and enjoy!
Rabbi Chaim Goldberg is a Fish Expert at OU Kosher.
To submit questions for future columns, please email our Webbe Rebbe at firstname.lastname@example.org or call the Kosher Consumer Hotline, at 212-613-8241.