The practice of fasting and abstaining from certain foods is an ancient one that has been practiced by many religions. In the early years of Christianity in Europe, the Church instituted the practice of requiring the faithful to abstain from eating meat on Fridays in memory of Christ's death. During the season of Lent, the Church also called for abstaining from eating meat on Wednesdays as well as on Fridays.

While the Church called upon all of the adult faithful to abstain from meat on these days, the rule really only applied to the rich as the poor generally could not afford meat. As many vegetarians and environmentalists point out, producing meat is a more costly way of providing the nutrition humans need as it takes time for the animals to grow to maturity and, during this period of growth, they are consuming plant life. Humans, being omnivorous, are able to consume and digest both plant and animal life which means it is more efficient, from a production standpoint, to produce and eat the plant life directly rather than produce it to feed to animals and then eating the animals.

It is important to note that the Church's directive called for abstaining from eating meat and did not mention, let alone require or even encourage, the eating of fish on Fridays. The Church's objective in calling on the faithful to abstain from eating meat on certain days was to provide them with a simple exercise to aid in their spiritual development. However, human nature being what it is, people usually react to new rules by looking for loopholes which enable them to comply with the letter of the rule but not necessarily the spirit of the rule.

In its abstinence rule, the Church simple required its members to abstain from eating meat with the idea that people would limit their food to vegetables and grains on Fridays. However, meat is generally considered to be the flesh of warm blooded land animals. Fish, on the other hand, are cold blooded water dwelling creatures. Using this technicality, people began consuming the flesh of fish in place of the flesh of animals on days of abstinence. Fish thus became a part of the culture of the Catholic Church.

People, of course, had been eating fish since the beginning of time, but the consumption of fish was limited to areas near waters where fish were plentiful. While St. Peter and some of the other Apostles and disciples of Jesus were fishermen and the New Testament describes Christ both accompanying them on a fishing trip and eating fish with them. However, this was due to the fact that they lived next to the Sea of Galilee which made fish a common food in that area. So, while the eating of fish had nothing to do with the fact that some of the Apostles were fishermen, the abstinence rule did began the slow process of making fish more common among the Catholic population in general and this slowly lead to some other economic and cultural changes in society.

As Europe emerged from the Middle Ages and began growing economically, a middle class began to form. While lacking noble titles and aristocratic ancestors, this group became the economic equals of the nobility and their rising incomes meant that the middle class could now afford to eat meat regularly as well. This, of course made them consumers of fish as they now had to follow the abstinence rules of their faith. The Industrial Revolution caused the middle and working class to expand further as wages for factory workers began to rise.

The economic growth produced by the Industrial Revolution attracted swarms of immigrants, many from Catholic countries in southern and eastern Europe as well as numerous immigrants from from heavily Catholic Ireland and Germany. As the incomes of these immigrants rose, they too found themselves able to afford more meat in their diets and, as a consequence found themselves substituting fish for meat on Fridays, just like the aristocratic lords and ladies in Medieval Europe, in order to comply with the rules of their faith.

Soon fish consumption by people living in America's interior cities like Louisville, Kentucky, Milwaukee Wisconsin, St. Louis Missouri and others equaled that of areas along the Atlantic coast whose fishermen ended up supplying much of the cod and haddock sold in the interior.

This increased consumption of fish in the industrial cities of the interior soon gave rise to the tradition of the Friday night Fish Fry, a custom that can still be found to this day in many of these cities.  With the advent of the five day workweek, Friday became the end of the workweek as well as the anniversary of the day on which Our Lord was crucified.  

Soon restaurants began offering Friday fish frys as a relatively inexpensive way for working and middle class Catholics to dine out with their families while abiding by the precepts of their faith.  The restaurants were soon joined by local Catholic Churches, American Legion and VFW Halls and other organizations which found inexpensive fish fry dinners to be a good way for their members and others to get together and socialize while, at the same time, raising money for the churches or organizations. 

Things began to change following the Second Vatican Council which met from October 11, 1962 to December 8, 1965. In early 1966 Pope Paul VI urged that the practice of fasting and abstinence be adapted to local economic conditions. Later that year the U.S. Conference of Catholic Bishops relaxed, but did not abolish, the rules on fasting and abstinence. However, the media and much of the laity interpreted these actions as abolishing the Church's requirement that the faithful abstain from meat on Fridays during the year and on Wednesdays and Fridays during Lent.

Through the centuries the Church in Rome had required, as a general rule, that Catholics abstain from eating meat on Fridays during the year as well as on Wednesdays and Friday's during Lent. However, there were exceptions to the general rule. Children under age 14, old people, pregnant women, people who were ill, the aged, travelers in certain circumstances, etc. were not required to follow the abstinence rule. Further, as the Church grew and expanded beyond Western Europe and as society changed due to economic growth, the Church in Rome gave national Bishop's Conferences and even individual local Bishops the power to modify the rules to make them compatible with local customs.

Thus, in the United States, Catholics were allowed to eat meat on the Friday following Thanksgiving (which is always on Thursdays) in recognition of the fact that most households had a generous supply of leftover meat from the feast the day before. Similarly, whenever St. Patrick's Day (March 17th), a major Irish-American holiday which occurs during Lent, fell on a Wednesday or Friday, American Catholics were not required to follow the abstinence rule.

Finally, local bishops would provide dispensations to secular groups hosting a meal on a day when Catholics were required to abstain from eating meat. This was in recognition of the fact that America is a secular nation made up of people of different faiths and that Catholics are active participants in secular society. So, whenever a secular organization with Catholics among its members planned an event that included a meal and fell on a day that the Catholic Church required its members to abstain from eating meat, the organizers simply requested from the local bishop a dispensation that would excuse Catholics attending the event from having to abstain from eating meat.

The actions by Pope Paul IV and the U.S. Catholic Conference of Bishops in 1966 relaxed but did not remove the Church's rule requiring Catholics to abstain from eating meat on Fridays.  

However, the confusion surrounding the relaxing of the abstinence rule led the vast majority of Catholics in the U.S. and elsewhere to stop abstaining from meat on Fridays.  In recent years the Church in the U.S. has managed to get many practicing Catholics to abstain from eating meat on Ash Wednesday and Fridays during Lent.  However, most either ignore or don't know that the Church continues to require that Catholics between the ages of 14 and 60 to fast and abstain from eating meat on Ash Wednesday and Fridays during Lent as well as either fast and abstain from meat day a week or perform some act of charity and sacrifice day a week in place of fast and abstinence.