Why Fish is Okay, but Not Meat on Fast Days (Interesting Answer from Thomas Aquinas!)


Many people ask why Catholics are permitted to eat fish on days of abstinence (“Fish Fridays”!), but not meat. After all, isn’t fish a kind of “flesh”?

The traditional Catholic allowance for fish on days of abstinence has a mystical relationship to the episode of the Great Flood of Noah, in which it rained forty days and forty night – just as Lent is a forty day period of universal cleansing. During this time, Noah and his family ate fish, since they were not permitted to eat the animals on board the ark. Moreover, the fish were preserved in the Great Flood (fish can swim), but land animals were not (they drowned). Hence, fish also play a part in the ministry, parables, and teaching of Christ – after all, many of the Apostles were once fishermen.

However, Saint Thomas Aquinas provides us with a more practical reason for why meat is not allowed, but fish are permitted:

I answer that, fasting was instituted by the Church in order to bridle the concupiscences [i.e. inordinate desires] of the flesh, which regard pleasures of touch in connection with food and sex. Wherefore the Church forbade those who fast to partake of those foods which both afford most pleasure to the palate, and besides are a very great incentive to lust.

Such are the flesh of animals that take their rest on the earth, and of those that breathe the air and their products, such as milk from those that walk on the earth, and eggs from birds [here is the traditional prohibition against eggs, milk, and cheese since they all come from land animals]. For, since such like animals are more like man in body, they afford greater pleasure as food, and greater nourishment to the human body, so that from their consumption there results a greater surplus available for seminal matter, which when abundant becomes a great incentive to lust. Hence the Church has bidden those who fast to abstain especially from these foods. (Summa theologiae II-II q. 147, a. 8)

Are there any nutritionists out there who can confirm this? Any comments?

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  • Cui Pertinebit

    The Fathers talk about how it goes beyond mere pleasure into the power to amplify the desire for pleasure. Flesh-meats and rich foods like eggs and cheese, stimulate the bodily passions. That’s why the Eastern Churches and the Orthodox abstain from them, and why the West used to do the same. Fish and vegetables do not have the heavy, soporific and libidinizing effect upon the body that these richer foods do.

    I’m still in the Orthodox Church, but am being received into Catholicism. I plan on continuing the standard fast, which used to be tradition for East and West alike – don’t eat until after 3, and stay vegan (save for fish/shellfish/etc.). I spent two years in an Orthodox monastery, too, where we also abstained from wine, beer and oil. Let me tell you, it really is true – you notice that the passions are much diminished by this diet, but on Saturdays and Sundays in Lent, when we were allowed to have wine and oil again, you noticed how much extra energy they provided, and you noticed how it was significantly easier to be lustful, angry, etc. I certainly notice a difference between the Vegetarian + Seafood diet, vs. meat and cheese. In my personal opinion, in fact, cheese and cream are worse than meat in this respect. But meat was a luxury in the ancient and medieval world, and poor folk generally only had meat on feasts and such. So, over time, the luxurious nature of the food made it the last remaining thing to be given up in Lent… and nowadays, only on Fridays. I think we could all benefit by returning to stricter practices from the rich Tradition of the Church.

Why Fish is Okay, but Not Meat on Fast Days (Interesting Answer from Thomas Aquinas!)


Many people ask why Catholics are permitted to eat fish on days of abstinence (“Fish Fridays”!), but not meat. After all, isn’t fish a kind of “flesh”?

The traditional Catholic allowance for fish on days of abstinence has a mystical relationship to the episode of the Great Flood of Noah, in which it rained forty days and forty night – just as Lent is a forty day period of universal cleansing. During this time, Noah and his family ate fish, since they were not permitted to eat the animals on board the ark. Moreover, the fish were preserved in the Great Flood (fish can swim), but land animals were not (they drowned). Hence, fish also play a part in the ministry, parables, and teaching of Christ – after all, many of the Apostles were once fishermen.

However, Saint Thomas Aquinas provides us with a more practical reason for why meat is not allowed, but fish are permitted:

I answer that, fasting was instituted by the Church in order to bridle the concupiscences [i.e. inordinate desires] of the flesh, which regard pleasures of touch in connection with food and sex. Wherefore the Church forbade those who fast to partake of those foods which both afford most pleasure to the palate, and besides are a very great incentive to lust.

Such are the flesh of animals that take their rest on the earth, and of those that breathe the air and their products, such as milk from those that walk on the earth, and eggs from birds [here is the traditional prohibition against eggs, milk, and cheese since they all come from land animals]. For, since such like animals are more like man in body, they afford greater pleasure as food, and greater nourishment to the human body, so that from their consumption there results a greater surplus available for seminal matter, which when abundant becomes a great incentive to lust. Hence the Church has bidden those who fast to abstain especially from these foods. (Summa theologiae II-II q. 147, a. 8)

Are there any nutritionists out there who can confirm this? Any comments?

You may also enjoy reading:

Download My Book for Free
Thomas Aquinas in 50 Pages
Over 15,000 copies downloaded! This is a quick and easy way to learn the basic philosophy and theology of Saint Thomas Aquinas. The Popes of the last 300 years have endorsed St Thomas Aquinas. Learn more through this accessible resources. Download it for free.