In the resurrection of our Lord Jesus Christ two major events happened:
- The resurrection itself
- The restoration of Adam and all his children to the paradise which happened on Friday
So the church wanted to celebrate the two events, the first one is well celebrated. What about the second one? We cannot celebrate it on Friday or Saturday since our Jesus Christ is still in the tomb or on Sunday because the celebration of the Feast of the Resurrection will supersede.
So the church chose the first day after the Feast of the Resurrection (Monday) to celebrate the restoration of Adam and his children and that is why people go to gardens (like the paradise) and eat eggs (symbol of the resurrection).
As for the salted fish, when Egypt was 100% Christian, the fish market would stop during the 55 days fasting, and at that time there was no coolers, so they used to salt the fish to be able to keep it for a long time.
Then after the feast day, all the Christians decided to eat the salted fish to help their brethren the Christian fishermen who did not sell any fish for a the 55 days.
