אֶת־זֶה֙ תֹּֽאכְל֔וּ מִכֹּ֖ל אֲשֶׁ֣ר בַּמָּ֑יִם כֹּ֧ל אֲשֶׁר־ל֛וֹ סְנַפִּ֥יר וְקַשְׂקֶ֖שֶׂת תֹּאכֵֽלוּ׃
Distes podereis comer de tudo o que está nas águas: todo aquele que tem barbatanas e escamas, esses podereis comer.
Da'at Zekenim
כל אשר יש לו סנפיר וקשקשת, “any maritime creature that possesses fins and scales;” our author asks why the details about fish had to be repeated here? [they had been given in Leviticus chapter 11. Ed.] Our author sees a reason for the repetition of the rules pertaining to which domesticated mammals and which birds could or could not be eaten, seeing that according to the Talmud tractate Chulin folio 61, that certain birds have a different name in Leviticus from the name given here by Moses, and in the case of the mammals the parted hooves are described slightly differently, so that we should know both categories are forbidden if the hoof is not split from front to rear.
Ibn Ezra
I have already explained the words fins and scales [comment on Leviticus 11: 9].