If I recall the article in the Catholic school magazine we used to get, there was a McDonald’s franchisee in a mostly Catholic neighborhood who was losing customers on Friday. He suggested he serve fish, the HQ said ok, and a star is born.
On another note, the same magazine ran a several part story about a man running for president. You never saw his face until the end - when they showed it was a black man. This would have been back in the 1960’s.
wiki:
“The sandwich was created by a McDonald’s franchise owner in Cincinnati, Ohio, named Lou Groen in 1962.[2][3] Groen owned a McDonald’s in a predominantly Roman Catholic neighborhood where his Catholic customers engaged in the practice of not eating meat on Fridays[3] (a practice more common in the ‘60s but that the Catholic Church continues to consider obligatory on Fridays during Lent).[4]”