You buy some Tropicana Orange Juice with Omega 3’s added. Your mother always told you to drink OJ with your Salami, so you pour a tall glass to go with your deli sandwich. As you’re pouring, the “OK fish” designation catches your eye. What are the implications?

You’re the cook in a large camp. Hurried and late on Friday afternoon, you grab what you think is a loaf of kishka from the freezer and toss it into the chulent. Shabbos morning you realize the chulent smells a little funny. Upon closer inspection you realize it was a loaf of gefilte fish. What now?

In an effort to lower your cholesterol you switch from hamburgers to grilled fish. Can you use the same grill? How well does it have to be cleaned?

You use Worcestershire Sauce to prepare your steaks. Your grilling buddies point out that it contains anchovies. May you continue to use it?

The Prohibition

The Gemara in Pesachim 76b states: “Fish that was roasted together with meat should not be eaten for it is bad for odor and for something else”. Odor refers to bad breath (Mordechai) “something else refers to tzaraas (Rashi).

The Shulchon Aruch rules (YD 116:2) that one should not eat meat and fish together because it causes tzaaras. The Rema adds that they should not be roasted together because ‘Reicha’ or smell is considered significant and transfers from one to the other but if done it is not forbidden. If they are cooked together (not roasted) or they are close enough that the juices ooze from one to the other, they are forbidden.

In fact, in the Darkei Moshe the Rema writes that even though when meat and milk mix if one is less than 1/60th we consider it nullified and it is permitted, in this case we won’t say that because of “chamira sekanta meisura”. This is a Talmudic concept that teaches that we are more stringent for health related prohibitions than other prohibitions. Some Poskim are lenient and allow it to be nullified in 60.

Fish and meat may be eaten consecutively, but there is a dispute as to whether one needs to wash their hands and mouth between them. Sefardim are stringent and Ashkenazim are more lenient. Many (Ashkenazi) Poskim say that one should take a drink and/or eat something such as bread between them. This is the source for the post fish lechaim. [There is a Halachic basis to not drink water after fish. Hence the minhag developed to drink schnapps].

The Leniencies

All this only applies to actual fish residue. One may use the same pots for fish and meat as long as they are cleaned well. (Unlike milk and meat, where we say that some flavor is absorbed in the walls of the pot themselves). Similarly, meaty knives may be used for fish as long as they are clean.

Magen Avrohom (173) writes that nowadays there is no danger in mixing fish and meat and perhaps there is room to be lenient. The universal custom is not like the Magen Avrohom. [The Rambam does not quote this Halacha, presumably for the same reason].

The Divrei Malkiel is lenient on Shabbos, as far as I know the custom is not to be lenient.

Fish and Milk

The custom among many Sefardim is not to eat milk and fish together (think lox and cream cheese, tuna melt). They are lenient with butter on fish though.

Kashrus Organization Policy

As far as I can ascertain, the OU will mark an item with more than 1/60th fish as OU fish. Less than 1/60th they will not mark, but the fish will be listed on the ingredient panel for those who are stringent. The primary application is kosher marshmallows and Worcestershire Sauce. I don’t know what the OK policy is as far as the Omega 3 OJ is concerned, if anyone knows please comment.