Stricter Than A Prohibition
‘We Rely on a Gentile…’
The Shulchan Aruch (Yorah Deah 116:2) rules: “One must be careful not to eat meat and fish together because it can cause tzaraas.” The Taz adds (ibid, s.k. 2) that since “a danger is stricter than a prohibition,” the mixture is forbidden even if the fish (or meat) is less than 1/60 of the mixture.
Similarly, it is forbidden to drink exposed water as per an edict of Chazal, even if the container is huge and any snake venom that may have slipped inside would be insignificant (e.g., 1/1,000).
Snake Venom Most Potent
The Shach disagrees (Nekudos Hakesef, ibid.). He maintains that while snake venom cannot be rendered insignificant (since it is extremely dangerous), other dangerous foods forbidden by Chazal do become insignificant if they are 1/60 of the mixture or less.
Ability To Distinguish
The Tzafnas Paneiach (264) also differentiates between snake venom and a mixture of meat and fish. Snake venom is dangerous by itself whereas only a mixture of meat and fish is dangerous. That’s why, while snake venom cannot be nullified, a tiny bit of fish in meat or meat in fish can be nullified if the taste is not detected. At that point, one can’t really speak of a mixture.
Our sugya mentions an incident involving Rabbi Yochanan and a kilkis fish that fell into a pot of meat. He ruled that if the fish could be identified and removed and there was no trace of the fish’s taste in the meat, the meat could be eaten. He relied on a gentile cook tasting it since a Jew couldn’t. We thus have a strong proof against the position of the Taz who maintains that no amount of fish can ever be nullified in meat or meat in fish.
Which Fish Constitutes a Danger in a Mixture?
The Chasam Sofer (see Responsa Dovev Meisharim 3:39) explains our Gemara in such a way that the proof falls away. Fish-meat mixtures, he argues, are only dangerous if the fish is kosher. (see the Ran to Avodah Zarah 35a). Some assume that the kilkis is a kosher fish (see Rashi, Avodah Zarah, and Ran, 39b; Rambam, as explained in the Beis Yosef, 83; and Shach, ibid., s.k. 18). However, Rashi writes (s.v. “kilkis”) that the kilkis is a non-kosher fish. Thus, Rabbi Yochanan was concerned with the food being prohibited, not dangerous.
We should emphasize that most poskim rule that in a mixture of meat and fish, the meat or fish becomes insignificant if it is 1/60 of the mixture or less (Shemiras Haguf Vehanefesh 1:4).
Danger of Meat and Fish Today?
Poskim state that, in our era, we do not see mixtures of meat and fish causing tzaraas. Some suggest that nature may have changed and such mixtures are not so harmful today (see Magen Avraham, 173, s.k. 1, and Mishnah Berurah, ibid, s.k. 3). According to certain opinions, only one fish is dangerous if mixed with meat and that is the binta (see Shemiras Haguf Vehanefesh, 1, s.k. 1).