For Egyptians, Sham Al-Nessim marks the advent of Spring. It falls on the first Monday after Coptic Easter, and it was linked to agricultural activity in ancient Egypt. It included fertility rites and ancient harvest festivals that were later, and unwittingly, attached to Christianity and the celebration of Easter. The date is not a fixed one: it is calculated according to the Coptic calendar -- and here "Coptic" means the Egyptian calendar, which had its origins in the annual Nile flood and the agricultural seasons.
It seems that Sham Al-Nessim is a holiday as old as Egypt. According to the Egyptian Information Service, the name is actually derived from the ancient Egyptian harvest season, Shamo, the "the renewal of life". According to Plutarch's Annals, the ancient Egyptians used to offer salted fish, lettuce and onions to their deities on this day.
This is only one of many stories concerning the holiday. Centuries ago people who believed in healing powers and other bits of folklore chose these types of food as part of pagan ritual, yet nowadays, out of the ritual of tradition, Egyptians still choose to celebrate -- and even die for it.
At the centre of the festival is fesikh, grey mullet; caught, piled high in containers, and left out until it is distended. When it is sufficiently putrefied, salt is added and the fish are left to pickle for a few months. Et viola, the fish that Egyptians are willing literally to die for is processed. It is no wonder that dozens are poisoned and several meet their fate every year during Sham Al-Nessim, usually as a result of botulism contracted from the foul-smelling feast.