Shailah of the Week by Rabbi Zvi Nussbaum
Rabbinic Coordinator, Kosher Hotline Administrator for the Orthodox Union
We know that eating fish and meat together is a sakana, dangerous! (For more on this topic, please refer to this previous shailah.) Does the same apply to eating fish together with dairy?
While Beit Yosef (YD 87:3) writes that it also applies to fish and milk, Rema (Darkei Moshe 87:4) disagrees! Most Ashkenazi poskim, including Shach and Taz, did not accept the chumra of not mixing fish and cheese, though some (such as the Pri Megadim YD 87:3) write that one should be careful in this regard. The Pitchei Teshuva (YD 87:9) points out that Rabbeinu Bechaye in his commentary on Parshat Mishpatim (Shemot 23:19) also forbade eating fish with cheese because of a possible danger to health.
However, most Ashkenazi poskim agree with the Chasam Sofer (YD 101), who writes that since Rambam, who was one of the greatest doctors, did not caution against mixing fish and cheese, and there is no mention of this in the Gemara, there is no need to be concerned.
Even many Sephardim who follow the ruling of the Beit Yosef differentiate between fish and cheese, which they view as a sakana, and fish and butter, which they permit.