Have the Fish…but Try not to Enjoy It

Well, it’s that time of year again: fast food restaurants are ratcheting up their fish sandwich ads, frozen fillets tilapia are featured in grocery store ads, and fish sticks are more prevalent in school cafeterias. At least, that’s the way it is in my neck of the woods. The season of Lent is upon us, and many people in this region are observing the time-honored tradition of swapping meat and poultry for fish on Fridays. Though I try not to be too opinionated on this blog, I find it hard to accept community fish fries advertised on my local radio stations as befitting for a time of self-sacrifice and abstinence. I say this because I picture fish fries as the grand finale for a summer day spent trawling around the lake and reeling in scads of “sunnies” and crappies, and then gathering with family and friends to kick back and indulge in crispy, salty, fishy morsels paired with ice-cold brews. If self-inflicted misery is the goal of “Fish Fridays,” people should eat lutefisk: a gelatinous, flavorless cod derivative traditionally paired with equally flavorless boiled potatoes and grim reflections of the ancestors who had to eat this glop.

But I digress. Call me cynical, but I tend to question traditions. This isn’t to say I’m against them; I just like to know why we do things. So, pertinent to this post: Why fish on Fridays? What makes fish so different from meat and poultry? These questions will be addressed from both historical and scientific views.


Full disclosure: I do not participate in abstaining from meat and poultry on Fridays during Lent. I grew up and still live among many people who do partake in this observance, and the tradition has always intrigued me. Of course, Fish Fridays touches on the subjects of religion, economics, and food – all of which can spark heated debates if allowed. So, to hopefully prevent mobs wielding torches and pitchforks from coming after me, I’ll keep this explanation brief and as neutral as possible.

  • Fish played a prominent role of several Bible narratives such as Jesus calling ordinary fishermen to be among his first disciples (Matthew 4: 18-22, NIV), the miracle of feeding a large crowd with just five loaves and two fish (Matthew 14:13-21, NIV), and Jesus sharing a meal of fish and bread with his disciples after the Resurrection (John 21:1-14, NIV). Preparing and eating fish is a tangible way to remember and connect with the people in these stories.
  • The crucifixion of Christ occurred on a Friday, and the sacrifice of giving up more luxurious foods in favor of fish commemorates Jesus’ sacrifice (Villarrubia, 2010).
  • One result of King Henry VIII’s infamous divorce from Catherine of Aragon and break from the Catholic church was the stigma placed on the consumption of fish as a religious observation (Godoy, 2012). This turn from habitual fasting with fish at the center of sacrificial meals hurt the fishing industry (and, probably, spiritual health of many people), and it wasn’t until 1547 when fast days were lawfully brought back to support the economy and culture that eating fish was no longer a social faux pas (Godoy, 2012).
Fish and vegetables: the makings of a “fast” meal.


Fish muscle varies from the muscle – and, therefore, meat – of mammals and poultry in several ways besides just being more suited for being served with tartar sauce (Zhou & Regenstein, 2009).

  • Fiber types (“white” for quick bursts of activity and “red” for long, sustained activity) are more divided from each other than in other vertebrates’ muscle.
  • Myosin (a large protein involved in flexing and relaxing muscles – movement, essentially) is less stable in fish than mammalian muscle.
    • Thermostability of fish myosin is so volatile, myosin properties will vary based on a fish’s living environment: hot-water, warm-water, cold-water, or ice-water. This is why fish tank temperature for pet fish owners is so critical and why tilapia and haddock can never be friends beyond pen pals.
  • Myoglobin (the protein responsible for carrying oxygen to muscles) in fish oxidizes more easily than myoglobin found in mammals, which can cause fish muscle to discolor rather easily.
    • The amount of myoglobin can also correlate to a fish’s diving habits that dictate the amount of oxygen storage required for epic deep-water dives (Zhang, Owens, Schilling, 2017).
  • The amount of collagen (a structural protein) in fish muscle is relatively low compared to collagen levels of mammalian muscle, but contributes to firmness of meat just like the collagen found in mammals and poultry.
  • Fish muscle has a greater concentration of polyunsaturated fatty acids (PUFAs) than mammalian or poultry muscle. PUFAs are prone to oxidize more quickly than the more stable monounsaturated and saturated fatty acids, and once oxidized can deteriorate the quality of meat’s texture and structure. However, since PUFAs are well-known for their anti-inflammatory properties among other health benefits, the presence of PUFAs that haven’t gone to pot is a key selling point for fish.

Also, muscle fibers of fish are not arranged in long, overlapping rope-like structures like those of mammals and birds. Instead, the fibers are arrange in narrow sheets called myomeres separated by thin layers of connective tissue called mycommata (Wood & Crompton, 2020). It’s this separation and the relatively low amount of collagen that allows cooked fish meat to “flake” (Troy, 2019). I don’t believe I’ve come across a recipe for beef, pork, or chicken that directs me to test for doneness by seeing if the meat flakes with a fork.

Fish muscle is arranged in narrow sheets separated by thin layers of connective tissue which include the protein collagen. Photo credit: Encylopedia Britannica, Inc.

So, in summary: The early Christians were right to recognize fish as an animal quite different from those of the land and air. After all, St. Paul wrote in his first letter to the Corinthians “Not all flesh is the same: People have one kind of flesh, animals have another, birds another and fish another” (1 Corinthians 15:39, NIV). It’s role in biblical narratives as a food of the common people and symbol of self-sacrifice persisted through the centuries to this present day when every fast food chain heavily markets fried fish sandwiches for 40 days each spring. Remember, though: the observation of Lent should be marked by self-reflection and sacrifice. So skip the spendy swordfish…and settle for the lugubrious lutefisk.

Bacon oversees his local mini-pond where, once the ice has melted, he will again wade with the fishes.


Godoy, M. (6 April 2012). “Lust, lies and empire: the fishy tale behind eating fish on Friday.” The Salt. Retrieved from https://www.npr.org/sections/thesalt/2012/04/05/150061991/lust-lies-and-empire-the-fishy-tale-behind-eating-fish-on-friday.

Troy, E. (4 September 2015). “Why does fish flesh have a softer texture than beef or chicken?” Culinary Lore. Retrieved from https://culinarylore.com/food-science:why-does-fish-have-a-softer-texture/.

Villarrubia, E. (16 February 2010). “Why do Catholics eat fish on Fridays?” Catholicism.org. Retrieved from https://catholicism.org/why-do-catholics-eat-fish-on-friday-2.html.

Wood, B., Crompton, R.H. (2020). “Vertebrate muscle systems Major types of vertebrate muscles.” Britannica. Retrieved from https://www.britannica.com/science/muscle/Vertebrate-muscle-systems.

Zhang, X., Owens, C.M., Schilling, M.S. (2017). “Meat: the edible flesh from mammals only or does it include poultry, fish, and seafood?” Animal Frontiers, 7(4), 12-18. https://doi.org/10.2527/af.2017.0437.

Zhou, P., Regenstein, J.M. (2009) “Fish muscle.” In M. Du, & R.J. McCormick (Eds.), Applied Muscle Biology and Meat Science (pp. 275-285). CRC Press Taylor & Francis Group.

Published by Amy G.

I'm on a mission to educate readers about meat and its part in human existence: its science, the many ways it's enjoyed, and the people who prepare it for others' enjoyment and nourishment.

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