The Primer on Meat and Fish—
Why is Fish Not Considered Meat and Permitted on Abstinence Days?
From a Catholic perspective, the distinction between fish and meat on days of abstinence (such as Fridays in Lent) is rooted in theology, tradition, and canon law, rather than purely scientific or dietary classifications. The Church’s discipline of abstinence is based on spiritual symbolism, historical precedent, and practical considerations rather than modern biological taxonomy.
1. Canon Law and Church Teaching on Abstinence
According to Canon Law (Codex Iuris Canonici, 1983, can. 1251):
"Abstinentia a carnibus vel a cibo ex decreto conferentiae episcoporum determinato servanda est omnibus diebus sextis, nisi aliqua solemnitas occurrat."
("Abstinence from meat, or from some other food as determined by the Episcopal Conference, is to be observed on all Fridays, unless a solemnity occurs.")
Here, the Church mandates abstinence from “carnes” (Latin for flesh meat) but does not include fish.
The Catechism of the Catholic Church also affirms:
"The penitential days and times in the universal Church are every Friday of the whole year and the season of Lent." (CCC 1438)
This means that Friday abstinence is a form of penance, following the example of Christ’s sacrifice on Good Friday.
2. Why is Fish Not Considered “Meat”?
A. The Traditional Distinction: “Flesh Meat” vs. Fish
In the Church’s historical classification, “meat” (caro) refers to the flesh of warm-blooded land animals—such as cows, pigs, sheep, poultry, and game animals. Fish, on the other hand, is classified differently due to:
Ancient Cultural Distinctions – In Greco-Roman times, fish was seen as a separate food group from land animals.
Theological Symbolism – Meat symbolized richness and feasting, whereas fish was associated with simplicity and sustenance.
Historical Abstinence Laws – Early monastic traditions considered meat a luxury, while fish was a staple food of the poor and a symbol of fasting.
Thus, fish was never classified under the Church’s traditional term for “flesh meat” (carnes).
B. St. Thomas Aquinas on Abstinence and Flesh Meat
Aquinas addresses this in the Summa Theologica (ST II-II, q. 147, a. 8), where he explains why the Church forbids meat but allows fish during fasting and abstinence:
"Carnium usus magis impedit mentem in contemplatione spiritualium quam piscium esus."
("The consumption of meat hinders the mind more in contemplating spiritual things than the eating of fish.")
He gives two reasons why land animal meat is prohibited but fish is allowed:
Symbolic Reason:
Animals of the land live with humans and symbolize worldly pleasures. Their meat was associated with feasting.
Fish live in water, symbolizing purification and detachment from worldly pleasures.
Thus, eating fish maintains a spirit of penance without indulging in rich feasting.
Physical Reason:
Meat from warm-blooded animals was seen as more nourishing and stimulating, potentially increasing bodily desires and making spiritual discipline harder.
Fish, being lighter, was considered less indulgent.
Aquinas reinforces that fasting disciplines the body, and since land animal meat was seen as more pleasurable, it was prohibited.
3. The Historical and Practical Basis for Fish Exemption
A. The Practice of Early Christians
Early Christians abstained from rich foods, including meat, dairy, and wine, during fasting.
Fish was a staple food for monks and ascetics, seen as a humble alternative to meat.
B. Medieval and Renaissance Developments
Abstinence from meat was observed widely, but fish remained an exception because it was easier to preserve and obtain.
The discipline allowed poorer communities, particularly those near coasts, to have an accessible protein source.
This explains why regional seafood customs developed in Catholic countries during Lent (e.g., salt cod in Spain, fish-based dishes in Italy).
C. The Influence of St. Peter and the Apostles
Christ called the Apostles “fishers of men” (Matthew 4:19), making fish an early symbol of Christianity (ichthys).
After His Resurrection, Christ prepared a meal of fish for His disciples (John 21:9), reinforcing its place in Christian tradition.
4. Common Objections Answered
Objection 1: Isn’t Fish “Meat” Biologically?
Yes, fish is flesh in a biological sense, but the Church’s classification is theological and disciplinary, not scientific.
The Church’s use of “meat” refers specifically to land animal flesh (carnes), not all animal protein.
Objection 2: What About Other Aquatic Creatures (Shellfish, Reptiles, Amphibians)?
Historically, some local bishops permitted aquatic creatures like alligators, capybaras, or beavers, based on their habitat (water).
While biologically inconsistent, this was a pastoral accommodation for communities dependent on these foods.
Objection 3: Isn’t Abstaining from Meat but Eating Lobster or Expensive Fish Against the Spirit of Penance?
Yes! The spirit of penance should guide one’s choices.
While fish is permitted, choosing luxurious seafood defeats the penitential purpose.
The Catechism encourages simplicity and sacrifice, so one should avoid indulgence even when eating fish.
5. Summary of Why Fish is Not “Meat” in Catholic Tradition
Canon Law and Church Teaching – The Church mandates abstinence from carnes (flesh meat), not all animal protein.
Theological Symbolism – Fish, living in water, represents simplicity and purification, while land meat is associated with feasting.
Aquinas' Explanation – Meat is more stimulating to bodily desires, making abstinence from it a stronger penance.
Historical Practice – Fish was a staple for early Christians, while meat was seen as a luxury.
Practicality and Charity – Abstaining from meat was a universal sacrifice, but fish was accessible to all.
Thus, fish remains permitted on abstinence days, not because it is biologically different from meat, but because of the Church’s spiritual and disciplinary traditions aimed at fostering penance and detachment from worldly indulgence.
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Historical Timeline of Fasting and Abstinence in the Catholic Church
The discipline of fasting and abstinence has evolved throughout Church history, adapting to different cultural and pastoral needs while maintaining the spirit of penance and sacrifice. Below is a historical timeline tracing the development of these practices:
1st – 3rd Centuries: Early Christian Fasting Practices
Jewish Roots – Early Christians inherited the Jewish tradition of fasting (e.g., fasting on Mondays and Thursdays) but adapted it.
Didache (c. 1st century AD) – Instructs Christians to fast on Wednesdays and Fridays instead of the Jewish practice (Monday/Thursday).
Tertullian (c. 200 AD) – Mentions "station days" (Wednesday & Friday fasts) as common among early Christians.
Fasting Before Baptism – Catechumens were required to fast before receiving baptism, a practice still reflected in the Easter Vigil fast.
Eucharistic Fasting – The practice of not eating before receiving the Eucharist began early.
4th – 6th Centuries: Formalization of Fasting and Abstinence
Council of Nicaea (325 AD) – Establishes Lent as a 40-day period of fasting, modeled on Christ’s 40 days in the desert (Matthew 4:2).
St. Athanasius (c. 340 AD) – Encourages the Lenten fast among Christians.
St. Augustine (354–430 AD) – Writes about fasting as a means of self-discipline and detachment from worldly pleasures.
Fasting Rules:
One meal per day, after sunset.
Abstinence from all meat, fish, dairy, eggs, and wine during Lent.
7th – 9th Centuries: Stricter Rules and the Introduction of Fish
Pope St. Gregory the Great (590–604 AD) – Clarifies that meat is forbidden on fast days, but fish is permitted because it is a "lighter food."
Monastic Influence – Monks adopt strict fasting, avoiding not just meat but also dairy and eggs (Eastern Orthodox still maintain this).
Fridays as Days of Abstinence – By the 8th century, every Friday (in honor of Christ’s Passion) becomes a universal day of abstinence from meat.
10th – 13th Centuries: Gradual Relaxation and Exceptions
Fasting Modifications – Some areas allow a small meal in the evening instead of strict fasting until sunset.
Canon Law of 1215 (Fourth Lateran Council) – Reinforces mandatory fasting during Lent and Friday abstinence but allows for regional variations.
Thomas Aquinas (1225–1274) – Defends theological reasons for abstaining from warm-blooded animal meat while permitting fish (Summa Theologica, II-II, q. 147).
Exceptions for the Sick and Travelers – Bishops begin granting dispensations for those unable to fast.
14th – 16th Centuries: Practical Adaptations
Late Middle Ages – Fasting rules remain strict, but practical exceptions arise:
Monks and laypeople often eat "fasting soups" with vegetables, grains, and fish.
The Church allows the use of butter and dairy in some regions (e.g., a special dispensation was required in medieval France).
Council of Trent (1545–1563) – Reinforces the importance of fasting and abstinence but acknowledges the need for pastoral flexibility.
Exploration and New World Foods – Foods like chocolate, coffee, and potatoes enter Europe, leading to debates about whether they break fasts.
Pope Paul III (16th century) – Allows beaver and capybara meat to be classified as "fish" for fasting purposes, since they are semi-aquatic.
17th – 19th Centuries: Gradual Relaxation in the West
Relaxation of Black Fasts – The strict one-meal-per-day rule begins to loosen, allowing two small meals and one full meal.
Missionary Adaptations – Missionary priests allow local fasting adaptations, such as using fish or local vegetarian foods.
19th Century Popes – Grant more exceptions for laborers, soldiers, and the poor who depend on meat for sustenance.
20th Century: Official Changes in Fasting Rules
1917 Code of Canon Law (Pius X, Benedict XV)
Requires fasting on Ash Wednesday, Good Friday, and all days of Lent (except Sundays).
Mandatory Friday abstinence from meat remains for the entire year.
Pope Pius XII (1950s) – Eases fasting requirements, allowing dairy and eggs on fasting days.
1966: Major Reforms Under Pope Paul VI
Apostolic Constitution Paenitemini (1966) redefines fasting and abstinence:
Fasting (one full meal, two smaller meals) required only on Ash Wednesday and Good Friday.
Friday abstinence from meat remains, but Episcopal Conferences may substitute other forms of penance.
United States Bishops (1966) – Lift the year-round Friday abstinence, making it optional outside of Lent (but still recommended).
21st Century: Current Catholic Fasting and Abstinence Rules
Canon Law (1983 Code, can. 1251-1253) states:
Fasting (ages 18-59): Required on Ash Wednesday & Good Friday.
Abstinence from meat (ages 14+): Required on Ash Wednesday, Good Friday, and all Fridays of Lent.
Other Fridays: Encouraged as a form of penance but not universally obligatory (varies by country).
Eastern Catholics & Orthodox – Still observe stricter fasting, including abstinence from meat, dairy, eggs, and even fish during Lent.