The Clean animals are listed in the book of Leviticus in the Torah. Many animals in the passage that are clean have the characteristic of having divided hoofs (feet) and also chew their cud (food) for it to be regurgitated. In the case in fish, scales and fins are present. If they do not have either one of them, they can be considered as an unclean animal.
This contains a list of clean animals that are specially mentioned from the Chapter 11 in the book of Leviticus (Old Testament) in the Bible. See the bible on Wikisource.
This list contains animals that are not specified in the Bible, but from the characteristics mentioned in the passage (Letvicus 11:1-47) in the Bible is considered to be clean.
"You shall take with you of every cleananimal by sevens, a male and his female; and of the animals that are not clean two, a male and his female; also of the birds of the sky, by sevens, male and female, to keep offspring alive on the face of all the earth.
Cleananimals were animals that God said the Israelites were not to eat.
Noah was to take a pair, a male and a female, of each kind of animal into the ark. But he was to take seven pairs of each of the cleananimals and birds.
It defines cleananimals essentially as ruminants, a suborder which includes about 69 recent genera, 192 recent species [Wilson and Reeder, 1993], and probably a comparable number of extinct genera and species.
Animals can't be expected to run laps and return to their cages without a lot of human supervision.
He asserts that the animals fossilized there range from the size of a small lizard to the size of a cow, with the average animal perhaps the size of a fox.