Written by Rabbis Eli Gersten, Yaakov Luban and Moshe Zywica of the Orthodox Union

In halacha, there is no difference between eating meat after fish or fish after meat. In both instances, rinsing or cleaning the mouth in between is essential. One should either eat a slice of bread or drink a beverage. According to the Shulchan Aruch (YD 116:3), if the meat or fish were touched by hand, the hands must be washed in between, except if a fork was used. According to the Rama (ibid.), there is no need to wash one’s hands either way, as long as the hands appear to be clean.

So, why is the custom to always serve fish first?

Rav Shmuel Wosner, zt”l (Kuntres Shemirat Haguf V’hanefesh), explains the common custom of eating fish before meat by referencing the Rambam in Hilchot De’ot (4:7). The Rambam writes that if a person intends to eat two foods, the one that is lighter and easier to digest should be eaten first. For example, chicken should be eaten before meat. Since fish is lighter than both chicken and meat, it is customary to serve fish first at the beginning of a meal.