Question

your visting france and some people have a paper fish what holiday is it

Answer 1

April Fools Day :)

Answer 2

It's the French way of celebrating April Fools. The reason they use paper fish is because when France adopted the Gregorian calendar in 1564, the people that still celebrated New Years in April were called "poisson d'avril" (April Fish) because it occurred under the zodiac sign of Pisces. Those who celebrated in April often had paper fish pasted on their backs as a prank.