A poisson d’avril is a hoax. It finds its origin in France and dates back to 1564. Under the terms of the Edict of Roussillon, it was stipulated that henceforth, in France, the first day of the year would be January 1st and not April 1st (or March 25th). Charles IX was at Roussillon fleeing an epidemic of the plague, hence the name of the Edict, also called the Edict of Paris. So, we are once again leaving behind the Julian calendar to adopt the Gregorian calendar.
Moreover, we are also looking once again at Charles IX (June 27, 1550 – May 30, 1574) who promulgated the Edict when he was 14 years old. He had become king when his brother François II died, at the age of 16, having reigned for a mere eighteen months. François II had been married, at the age of four, to six-year old Mary, future Queen of Scots.
Marguerite de Valois
Charles IX is the king whose mother, Catherine de’ Medici, manipulated into ordering the St Bartholomew’s Day massacre, which took place on August 23, 1572, six days after Marguerite de France, Dumas père’s Reine Margot and Charles IX’s sister, married, against her will, Henri IV, the Huguenot King of Navarre who became Henri IV King of France and of Navarre, when Henri III died, in 1589.
the reasons changed but the feast remained
As we have seen in the dating of Christian feasts, although renamed, the feast remained. On that day, an exchange of gifts became customary, except that people enjoyed giving foolish gifts to persons who were not aware of the fact that April 1st or March 25th no longer marked the beginning of a new year. Often a fish was given as the feast took place during Lent, a time of year when one did not eat meat. As well, the fish had been a symbol for early Christians.
Chaucer’s Canterury tales, 1392
It would appear however, that fools were celebrated long before January 1st became the first day of the year. Again, we may have Chaucer to thank for this information. In the Canterbury Tales (1392), the “Nun’s Priest’s Tale” is set Syn March bigan thritty dayes and two. The 32nd of March would be April 1st.
But Fools Feasts predate the Christian era. The moment one starts digging into the origins of Feasts, one lands in the Middle East or in India.
Terrible pranks have occurred on April 1st. One is an invitation to see lions washed at the Tower of London on April 1, 1698. No lion was washed, but people took the invitation seriously.
— Invitation to see lions washedEric Satie: Première Gymnopédie, Alexandre Tharaud (please click on the title to hear the music)