parashah shemini

G‑d gives the commandments of Kosher, explaining how to distinguish between kosher and non-kosher animals, fish, and birds. Kosher animals must chew their cud and have cloven feet. The Torah lists four animals that have only one of these attributes, but not both, and are therefore non-kosher. 
Kosher fish must have fins and scales. 

Mosaic scales kosher fishon a CD