Чешуя
Какую "чешую" мы считаем "чешуей":
A: “Kaskeses” is generally translated as scales. Nonetheless, not all scales are considered kaskeses. This is because the Ramban, in his commentary on the Torah tells us “kaskeses” are scales that can be easily removed by hand or with a knife without tearing the skin. Scales that are embedded in a fish (or are not visible to the naked eye) are not “kaskeses”. The Ramban’s definition is universally accepted, and in fact the Rema rules that those scales that cannot be easily removed (according to the parameters that will be discussed below) cannot be called “kaskeses”.
(и далее по ссылке - http://www.kashrut.com/articles/fishfaq/ )
A: “Kaskeses” is generally translated as scales. Nonetheless, not all scales are considered kaskeses. This is because the Ramban, in his commentary on the Torah tells us “kaskeses” are scales that can be easily removed by hand or with a knife without tearing the skin. Scales that are embedded in a fish (or are not visible to the naked eye) are not “kaskeses”. The Ramban’s definition is universally accepted, and in fact the Rema rules that those scales that cannot be easily removed (according to the parameters that will be discussed below) cannot be called “kaskeses”.
(и далее по ссылке - http://www.kashrut.com/articles/fishfaq/ )