Chabad.org — English translation + Rashi
Torah Temimah on this passuk (citation pointer only). Core text below is the Chazal derasha as recorded by TT — not TT’s explanatory voice. “זכרנו את הדגה” — Rav and Shmuel dispute: one says actual fish, one says arayos (forbidden relations). “Chinam” means free of mitzvos.
English: Rav and Shmuel disagree: one says actual fish, and one says forbidden relations… and the one who says forbidden relations [derives it from] “chinam” (free).
Double reading of “dagah” — surface craving for food, deeper craving for the free-of-commandments life of Egypt.
The midrash refuses to leave the complaint at the level of cuisine alone.