Leviticus 11:9-10

Whatsoever hath fins and scales Both of them. Such fishes being more cleanly and more wholesome food than others. All that have not fins nor scales shall be an abomination A late commentator, by a strange mistake, probably of the press, says here: “Fish with scales sooner incline to putrefaction than those that are without.” The fact is exactly the reverse. These are what medicinal writers call pisces molles, the soft kind of fish. And, as all sorts of fish, according to Dr. James, “are very subject to an alkaline putrefaction, so those without scales incline sooner and more to putrefaction than those furnished with them, and shell-fish most of all. And it may be laid down as a certain rule, that, of all sorts of animals, whether terrestrial or aquatic, those which putrefy soonest, incline the juices of our bodies most to putrefaction, when used as food, and so are least fit for ailment.”