The 1st of April falls very often during Christian Lent and allows a playful and light break in the midst of austerity before Easter. The fact that April 1 falls during Lent could explain the use of fish, which is the kingly food of Lent.

April Fool's Day has its origins in antiquity:

April 1st falls 12 days after the spring equinox and so it is possible that this festival has its origins in antiquity. One day was devoted to the God of laughter in ancient Greece. This day was devoted to the pranks, the crazy and the reversal of roles as during the Carnival. This tradition was taken up by the Romans with the goddess Aphrodite. In Spain the day of the pranks falls on the day of the Innocents on the 28th of December and in England the day of the pranks is called April Fool's day is the day of the fool of April. 

The most famous origin of April Fool's Day: 

April 1 is the day of hoaxes, jokes and pranks. Where does the tradition of hanging fish in the backs of people come from, shouting "April Fool's Day"?

As always, there is no single origin, but several origins at April Fool's Day. The feast of April 1st falls 12 days after the spring equinox.

The most famous origin of April Fool's Day:

The best known origin of the April Fool's fish is the decision of Charles IX (King of France). With the Edict of Roussillon, August 9, 1564, Charles IX established January 1 as the first official day of the year.

 If the first of April is the day of pranks and jokes in some countries, everyone has a day devoted to pranks but it does not always fall on the same date.

In France, Belgium and Switzerland: April Fool's Day is the same.

In Germany and the Netherlands the party also falls in April and is called "Aprilscherz"

In England the day of the pranks is called "April Fool's day" is "the day of the fool of April".

In Scotland the party lasts 48 hours and is called "Cuckoo of April".

In Spain the day of the pranks falls on the day of the Innocents on December 28th: ​​"dia de los santos inocentes".

In Portugal the feast of pranks takes place without fish but with flour. The victims of the stuffing are found covered with flour!

In India: The Feast of Pranks in India takes place on March 31 and is called "Huli", it is held on March 31st.

In Quebec, the feast of pranks is that of fish: "Running the April Fools".