Commentary for Deuteronomy 14:10

טמא הוא לכם, “it is ritually impure for you.” The word טמא here is not to be understood in the ritual sense of impurity, the person having contacted such animals requiring to perform purification rites before handling matters that are holy, but is an expression for something detestable. The concept of ritual impurity does not exist concerning fish. The expression טמא as clearly meaning something detestable is found in Ezekiel 4,13: “shall the Israelites eat their bread unclean in a disgusting unappetizing manner (among the nations that banish them?)”