By: Rabbi Yaakov Luban
The Torah states that kosher mammals are those which chew their cud (ruminants) and are cloven-hoofed. The following animal species are among those considered to be Kosher: Addax, Antelope, Bison, Cow, Deer, Gazelle, Giraffe, Goat, Ibex and Sheep. In addition, meat and poultry require special preparation, which will be discussed below.
The Torah does not enumerate specific characteristics to distinguish permitted and forbidden birds. Instead, it enumerates 24 forbidden species of fowl, while all other birds are considered to be kosher. Nonetheless, for various reasons, in practice we eat only those birds which have an established tradition that the species is kosher.
In the United States, the only poultry accepted by mainstream kashrus organizations as kosher are chicken, turkey, duck and goose.
The Torah establishes two criteria to determine what are kosher fish. The fish must have fins and scales. The scales must be easily removable without damaging the skin. [Generally, scales on kosher fish are either thin, rounded and smooth-edged (cycloid) or narrow segments that are similar to teeth of a comb (ctenoid)]. All shellfish are prohibited. Unlike meat and poultry, fish requires no special preparation. Nonetheless, the fish scales must be visible to the consumer in order to establish the kosher status of the fish. Therefore, filleted or ground fish should not be purchased unless properly supervised, or the fillet has a skin tab with scales attached to the flesh. Furthermore, purchasing fish in a non-kosher fish store is problematic, even if the scales are intact, because the knives and tables are not kosher, and Rabbinic guidance should be sought.
Rabbinic law prohibits consumption of fish and meat together.
Processed and smoked fish products require reliable rabbinic supervision, as do all processed foods.