The Gemara Pesachim (76b) teaches that one may not cook fish and meat together since this combination is considered a sakana. Shulchan Aruch (Y.D. 116:2-3) adds that one may not even eat meat after fish or fish after meat unless one eats and drinks in between1. Rama adds that one should not cook open meat and fish in the same oven because of raicha (aroma), though bidieved we say that raicha lav milsa. Magen Avrohom (O.C. 173:1) questions whether this sakana still exists today, however the minhag is still to be machmir.
Taz 116:2 says that fish cooked with meat is forbidden, even if the fish is batel b’shishim. Although issurim are batel b’shishim, since fish and meat is a sakana, we have no right to assume that it follows the same guidelines. “Chamira sakanta m’issura”.
However, Shach (Nikudas Hakesef) disagrees and maintains that fish is batel b’shishim in meat. This is the accepted opinion of most poskim. The Shevus Yaakov adds that since today it is questionable whether there exists any sakana (Magen Avrohom), one need not be machmir when there is shishim.
Therefore, products that contain amounts of fish that are not batel b’shishim must be labeled OU Fish, so that consumers will not unwittingly eat the product together with meat. If the amount of fish in the product is batel b’shishim, we do not require the product to be labeled OU Fish, provided that the fish ingredient is mentioned somewhere on the packaging. In this way, those who wish to be machmir for the opinion of Taz can do so by scanning the ingredient label. If the fish ingredient is not listed on the label or is ambiguous, (Omega-3 oil) then the product should be labeled OU Fish.
However, Rav Belsky said that if the product contains fish gelatin that is batel b’shishim then there is no need to label the product OU Fish even if it does not appear in the ingredients. For example, some flavors use fish gelatin as a carrier and would not be listed. If the amount of gelatin is batel b’shishim, there is no need to label the product OU Fish, even though fish is not listed on the packaging. Since fish gelatin is denatured and then refined, it is unclear whether there is any sakana for it to be eaten with meat. In this case, we need not be machmir provided it is batel b’shishim.
Although there is no chashash that dairy items will be eaten together with meat, still it is proper to label them OU Dairy Fish if the fish is not batel b’shishim to accommodate Sefardim that consider it a sakana to eat dairy and fish together.
It should be noted that though there is a sakana to eat meat and fish together, it is permissible to cook meat in fish kailim or to cook fish in meat kailim3. This is even true of a davar charif. For example an onion cut with a meat knife may be cooked together fish4. However, all of this is provided that the kailim are clean from all residue. It is not sufficient to merely wipe off a knife or spatula that was used for meat to then use it for fish, but rather it must be properly cleaned.
Summary: Because of the potential sakana of eating fish and meat together
• We must label foods OU Fish if they contain levels of fish that are not batel
• If the amount of fish is batel and it is listed on the ingredient panel then it need not be labeled OU Fish.
• Fish gelatin that is batel in a product need not be labeled OU Fish
• It is proper to label dairy items that contain fish OU Dairy Fish
• Although there is no sakana to cook fish with meat kailim, the kailim must be clean.
1. Shulchan Aruch also requires washing one’s hands between fish and meat, but Rama says that this is not necessary.
2. It is clear from the Poskim that discuss this issue that they are still concerned about sakana even today. However, the opinion of the Magen Avrohom is used as a mitigating factor when there are other reasons to be lenient (See Shevus Yaakov III:70 and Yad Efrayim Y.D. 116).
3. Issur V’heter brought by Taz Y.D. 116:2
4. Sefer Davar Charif 15:3