Dagim [fish] means Daagot [worries/concerns] about spirituality, meaning deficiencies. On Shabbat [Sabbath], when everything is corrected, the worries become food. In Egypt, the worries were for nothing, meaning without Mitzvot [commandments]. If the worries concern self-reception, the body is worried and we do not need to do much work. But if the worry is for the purpose of a Mitzva [sing. of Mitzvot], the body does not let us worry.