Eels are fish

I was curious to see what would happen if I clicked the "Unsubscribe" button at the bottom of this page, and sure enough, it told me that I unsubscribed. Neat.

Incredibly, I actually did learn this today because it was in the NYT crossword and I went down a very similar rabbit hole. I never made it to Freud, though, after I discovered and got sucked into the European Union Eel Regulation Framework[1].

If you, like me, are masochistically fascinated by this kind of “I can’t believe this is a real thing that the government actually does” documentation I recommend giving it a once-over.

1. https://oceans-and-fisheries.ec.europa.eu/ocean/marine-biodi...

I regret to report that there is surely no such thing as a fish.[0]

[0] https://quoteinvestigator.com/2024/12/04/no-fish/

Apparently we are all fish. Or fish don't exist.

To explain: if you want to define a taxonomy in which all things that look like fish and swim are 'fish' then we are too. We are more closely related to most 'fish' than sharks are. I.e the last common ancestor of herring AND sharks is older than our & herring's LCA.

Hank Green recently did a couple of videos on the topic

https://www.youtube.com/watch?v=On2V_L9jwS4

https://www.youtube.com/watch?v=-C3lR3pczjo

https://www.youtube.com/watch?v=ElpRJQ2FZiM

Here's a long-form article on the same topic (the 19th century search for the spawning ground of eels)

https://www.newyorker.com/magazine/2020/05/25/where-do-eels-... ("Where Do Eels Come From?" (2020))

https://news.ycombinator.com/item?id=23265000 (56 comments)

I love these 'wait, what!' moments in biology. Thanks for sharing this - definitely going to be my fun fact for the week!

At least you could exclude jawless, cartilaginous, and lobe-finned fish. That would leave you with 99% of what people call fish. But as said it would exclude sharks, they would need to be their own group.

More bothering me is that there are no trees. There are just many plants which have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight.

It also reminds me of a bit in Unsong, a book where there's quite a bit of discussion about whether the whale is a fish or not.

For reference, this idea is becoming more popular recently due to the Green brothers: https://youtu.be/-C3lR3pczjo

> Apparently we are all fish. Or fish don't exist

Apparently if you go even further back and apply the same logic, we are all fungi. In fact, we both can synthesize vitamin D from sunlight, although I'm not sure if we do it the same way or use it for the same purpose.

I could be way off base here, and I don't honestly know much about biology... but just because two species don't have recent common ancestors, doesn't mean they couldn't have co-evolved and ended up very similarly, right? Wouldn't this be grounds for relating their classification?

Huh, someone (OP?) will potentially miss the next edition of this newsletter.

I just noticed the URL has a lot of parameters, probably for their analytics to identify the subscriber.

I read the blog post. Then I thought "surely the eels in my local southern German lakes can't be from the sea". But sure enough, the European eel hatches close to the Bahamas.

I audibly wtf'ed multiple times while going down this rabbit hole. Thanks!

https://en.wikipedia.org/wiki/European_eel

Yeah. Terms like "fish" and "tree" are more like "quadruped" than they are like "rodent".

Yes, fish, like trees or reptiles, don't exist as a monophyletic group (or clade).

Convergent evolution happens all the time but taxonomy is nonetheless based on ancestry.

It looks like the URL won't load without both the p (presumably page?) and s (presumably subscriber?) parameters, and there was no other way to share it.

I wonder what the point is of having a newsletter that doesn't have an indexed web version. It's just a blog, right? Just one that happens to arrive in your inbox as well. What's the downside of listing the entries on the author's homepage as well, making them available to everyone?

While reading an article, I went to check how an eel differs from a lamprey - and I found out that a lamprey isn’t actually a fish

> things that look like fish

Well, apart from the circularity, we don't look like fish, do we? What we look like, we define, just like we define what 'fish' is. There's no need to go all Linnaeus about it.

This is just a consequence of life beginning in the ocean. Land-based life is related to ocean-based life at the point of the fork, and there were prior forks which, by definition, remained in the ocean.

Does this hold even if we don't include whales and dolphins in "things that look like fish"?

Everything is a secret third thing.

I had the same thought. I always knew they were fish but always assumed they were local fresh water fish. I mean everyone talks about how Salmon does this incredible journey. If there was another species which did something equally incredible I should have heard about it.

Thanks for the link! A rabbit hole indeed.

My stance is somewhat similar, I think? Arguments that try and precisely define "fish" in some sort of "context free" space are doomed because people don't think of terms outside of context.

Looking at the Wikipedia article for fish, it looks like a reasonable definition would be:

* Everything in the subphylum vertebrata (i.e. vertibrates)

* Except tetrapoda (tetrapods: amphibians, reptiles, mammals and the like).

It's not perfect because tetrapoda does fit within vertebrata in a biological / genetic sense (as a sibling comment put it: fish is not a monophyletic group). But it's a precise enough definition that I don't think we need to claim that we're all fish or that there's no such thing as a fish (as the QI elves would say).

For a fun somewhat related topic, it was neat to see the hierarchy of strings and characters in Common Lisp the other day. Can be used to illustrate a bit of the shortcoming of using ancestry to answer if two things are related. https://lispcookbook.github.io/cl-cookbook/strings.html#stri...

Yes, the issue is the ancestry between "fish" being very distant. It doesn't matter if you exclude marine mammals. Many fish in the ocean are still more closely related to beings on land than another fish. It's the equivalent of calling all flying animals birds. If we excluded bats from this new definition of "bird" then a bumblebee won't suddenly become more closely related to a Buzzard.

Fish exist, and we're not fish. Fish just isn't a monophyletic taxonomic category. If you allow "fish" to be a list of all those animals that look like "fish" and swim like "fish", you'll end up with a bunch of animals who's most recent common ancestor is also the most recent common ancestor of all tertrapods (including humans), so "we are all fish". But if you don't demand a single common ancestor & instead just have a list of several different taxonomic classes you can define "fish" as anything in the list, thereby excluding humans.

It's like the difference between culinary berries (sweet parts of plants) and biological berries (parts of plants containing the seeds internally). Tomatoes are not a culinary berry, but are a biological berry. Strawberries are a culinary berry, but not a biological berry (the seeds are on the outside). It's confusion caused by mixing a jargon use of a word with the common use of that same word.

> 399 Court St, Brooklyn

The address in the footer appears to be a cafe: https://www.google.com/maps/place/389+Court+St,+Brooklyn,+NY...

That's 389

But what about our precious friends the coelacanths?

Edit: foolish me coelacanths are not tetrapods

But a better question may have been regarding the lungfishes

Also "horizontal gene transfer" happens in bacteria, and even happens in multicellular sexually-reproducing organisms after viral infection in some cases. Taxonomy should be a directed acyclic graph, not a tree.

Those aren't the problem. The real issue is that the tetrapods which evolved into most land animals (amphibians, reptiles, birds, mammals) are further down the phylogenetic tree of bony fishes than coelacanths and lungfish, which are further down the tree than cartilaginous fishes like sharks and rays, which are further down the tree than jawless fishes like lampreys and hagfish.

In taxonomy, it's called a "Paraphyletic group" [1].

[1]: https://en.wikipedia.org/wiki/Paraphyly#Examples

usual reminder that European eels[0] are close to extinction, being critically endangered, and yet, for reasons, they are still being fished and eaten all over.

[0] https://en.wikipedia.org/wiki/European_eel

There's a chapter in Moby-Dick with a similar discussion.

Not a surprising result given that complex sea life significantly predates complex land life. It's had much longer to genetically diversify.

Similarly either we are all black, or black as a genetic race doesn't exist. The genetic diversity within humans in Africa exceeds the diversity outside of it. You can find two "black" Africans that are more genetically different than an Australian aborigine compared to a red headed Irishman.

Mammals include orcas and whales

Also interesting that eels, much like crabs, are a body form that has evolved many times in various ancestral lineages.

Suggest looking up the word "spat" and relatedly "spate"

And orcas and whales are not fish.

The author does not appear to be aware of this but eels are not the most snake-like among fish.

Already the Ancient Greek and Roman authors had a classification of fish, where eels where less snake-like, because they have pectoral fins, while the most snake-like group of fishes consisted of morrays and lampreys, both of which have neither scales nor any kind of fins, being less similar to other fish than eels.

The loss of the legs and the elongation of the body, resulting in a snake-like form has happened not only in many groups of vertebrates, including eels and morrays, caecilian amphibians, snakes and several groups of legless lizards, but also in many worms, e.g. earthworms and leeches, which evolved from ancestors with legs. Even among mammals, weasels and their relatives have evolved towards a snake-like form, though they still have short legs.

It surely does. This website is a good way to visualize the common ancestor of the bottlenosed dolphin and zebrafish. It's the same common ancestor as a human and a zebrafish, or a bird and a zebrafish. It's an ancient ancestor!

https://www.onezoom.org/life/@Gnathostomata=278114?otthome=%...

It's much more valid for trees. They've evolved many times and there is no common ancestor that is itself a tree.

Fish evolved once, and then a specific subgroup is excluded. That's fine.

There's a certain species of ape that takes offense at this, and doesn't like to think of itself as a "fish".

I enjoyed this but was sorry to see the author mentioning eating eels without mentioning that they're in critical decline. https://courses.lsa.umich.edu/healthy-oceans/freshwater-eels...

> Apparently we are all fish. Or fish don't exist.

I get very annoyed at this argument. It pretends that the only classification systems are strictly following a single ancestor or ignoring ancestry entirely.

The common definition of fish is neither of these. It's paraphyletic. Everything descended from A, except things descended from B and C.

But what about bees?

https://www.loweringthebar.net/2022/06/court-says-bees-are-f...

Human embryogenesis would like to disagree with you.

https://www.bbc.co.uk/news/health-13278255

Or the book "why fish don't exist", which got a lot of press last year if you consume media outside of youtube.

"Lampreys /ˈlæmpreɪz/ (sometimes inaccurately called lamprey eels) are a group of jawless fish"

I'm not sure what you mean? Jawless fish are pretty far from most fish but that's not much of a reason to say they're not fish.

As someone whos allergic to fish, I ALSO learned eels are fish when we got some roasted eel as an appetizer and I had an anaphylaxis flare up :P

You should have used "phylogenetic taxonomy". A "taxonomy" is literally any way of grouping organisms, like "all red things" (mature salmon, some roses, red algae).

They could have a similar phenotype without being genetically similar.

Except that "quadruped" is (AFAIK) phylogenetic: Tetrapoda.

Evolving from doesn't make you the thing, does it? It makes you something else. Fish in particular, since that's a group of animals named by us, based on physical appearance.

Wait until you figure out that cucumber is a fruit.

Not sure of that last claim, as Australian natives are (AFAIK) considered one of the very oldest groups to separate from other Homo sapiens. IIRC, they're the only major group that has no Neanderthal DNA, because they migrated/were separated before H. sapiens met H. neanderthalis.

That's a month old. I heard it over a year ago.

It goes from 410 to 389 in streetview. Gotta be in the middle of those.

You know what I say to that? Go back to Sumatra, ya ginger galoot!

"I want to be like you-u!" Yeah, right.

Fungi and Animalia split from Eukarya. Fungi didn't exist before then.

I realize "we are all eukaryotes" doesn't have the same punch...

Ontogeny does NOT recapitulate phylogeny.

Exactly.

But I believe in weak Haeckel's principle.

They all breed in the Sargasso Sea, so... critical habitat risks.

Nope.

But geese are.

> Evolving from doesn't make you the thing, does it?

Depends on the system of taxonomy; in phylogenetic taxonomy, that’t exactly how membership in a clade is determined.

I'm curious - are you allergic to both bony and cartiligenous fish?

TFW random eel content popping up while i enjoy my unagi.

"We don't know where eels come from" https://www.youtube.com/watch?v=y0UIJekwyPY

GPT-5 says that now its not. So while lampreys are technically fish under traditional definitions, modern evolutionary science places them as one of the most primitive branches of vertebrates—not part of the “true” jawed fish group.

Except that you can come up with a decent definition of "fish" and "quadruped", whereas there's no definition of "tree" that covers all the cases.

https://www.theatlantic.com/science/archive/2018/04/how-do-y...

I put in 399 and I got an apartment block.

First of all: I think it's ok if the definition of fish is a bit blurry around the edges.

But actually I think coelacanths are quite a fun example. I hadn't heard of these before, thank you!

Yes, they're not tetrapods, but (I've just discovered) they're not even vertebrates (no spine). According to my definition, they shouldn't be fish, but they do seem quite fish like.

They are chordates (they have a spinal cord, just no backbone for it), so I could expand my definition to any chordate that isn't a tetrapod. But there are some rather non-fishy chordates [1] so that doesn't work either.

[1] https://en.m.wikipedia.org/wiki/Tunicate

(For those that don't know, the top level subclassification of animals is phylum. There are a lot of phyla but a common ones are chordates (all vertebrates plus a few odd animals like discussed above), arthropods (insects and insect-like things like spiders and crabs), and molluscs (like slugs and clams). When I was at school, animals were just vertebrates or invertebrates but the reality is more interesting. I went down that rabbit hole when I found out that, weirdly, octopuses are molluscs.)

They're not taxonomically fish (even if you want a monophyletic category & thus count mammals as fish), they're not colloquially fish, they're legally fish under California Fish & Game Code § 45, but they're not necessarily legally fish in other jurisdictions or other subsections of the California Fish & Game Code. Because laws also define words to create jargon, and thereby new meanings dissociated from their common use. The extra fun bit is that other parts of the law can choose to define "fish" differently, for other purposes. Jargon has scope, and allows overloading.

There are lineages in Africa that split from other lineages in Africa before the Australian aborigine split. Add on more frequent (but still rare) mixing for even more diversity. Mixing makes the majority more homogeneous but can increase diversity at the extremes.

> * tetrapod (/ˈtɛtrəˌpɒd/;[4] from Ancient Greek τετρα- (tetra-) 'four' and πούς (poús) 'foot') is any four-limbed vertebrate animal of the clade Tetrapoda (/tɛˈtræpədə/).*

Huh. I always thought it was a more generic term for any four-limbed animal. TIL, I guess!

I don't know where it got that idea because I only see a few people using the term "true fish" and they're using the normal definition of vertebrates. If you want to be extra restrictive then there's multiple options. If you really want to exclude tetrapods you might use rayed fish. And there's also bony fish if you think sharks aren't quite right having only cartilage. Who uses jawed fish in particular?

> They are chordates (they have a spinal cord, just no backbone for it)

None of the cartiligenous fish have backbones. Nor any other bones.

Coelacanths have backbone-functioning cartilige.

Honestly, I can't think of a non-tetrapod animal that is four-limbed. I mean, unless you cut one leg off a starfish.

Eels were commonly currency:

https://www.atlasobscura.com/articles/medieval-eel-rent-map-...

I'm surprised to learn that it is surprising that eels are fish. I mean, they live in water, they have fins, they're generally fish-shaped... What's more surprising is their incredible life cycle and reproductive journey. I'm surprised the author didn't put that in the title.

Oh, but you should not classify living beings according to their habitat and behaviour; classification based on the degree of the phylogenetical relationship is obviously superior and the only truly reasonble one.

We are also fairly closely related to fungi, which is why it’s tricky to make good systemic fungicides. They always go after the liver.

Melanin apparently predates the split between fungus and animal kingdoms.

> Fish exist, and we're not fish.

Sudden flash of A Shadow over Innsmouth.

Orcas and whales are flip floppers (no pun intended).

We left the water and they went back. (I have a theory that given enough time, Labrador retrievers would form a new branch of marine mammals with similar morphology to seals).

I have same feeling for multiple email-newsetters I've encountered over the years

"why is there no blog-like archive?"

it feels like they will be prime example for modern lost media

There is an entertaining book related to this. Why Fish Don't Exist by Lulu Miller.

https://www.goodreads.com/book/show/50887097-why-fish-don-t-...

I can't tell if you are being facetious or not.

Recommend "The Truth About Animals" by Lucy Code [0]. It has good chapter on eels. They take a left and go to the USA or take a right and go to Europe.

[0] https://www.goodreads.com/book/show/34211802-the-unexpected-...

Some HN threads on this topic (meaning the "Eel-Rents Project" organized by John Wyatt Greenlee),

https://news.ycombinator.com/item?id=35997727 ("To Pay Rent in Medieval England, Catch Some Eels (atlasobscura.com)", 42 comments)

https://news.ycombinator.com/item?id=25543802 ("Paying Medieval Taxes Using Eels (historiacartarum.org)", 14 comments)

https://news.ycombinator.com/item?id=34284363 ("English Eel-Rents: 10th-17th Centuries (historiacartarum.org)", 12 comments)

> "One enormous transaction shows that Ely Abbey, now known as Ely Cathedral, paid Thorney Abbey 26,275 eels to rent a fen (similar to a wetland),"

Your article left out a neat twist: the name "Ely" is actually derived from the word "eel"!

I can HIGHLY recommend the book: "Book of Eels" by Patrik Svensson

Eels are incredibly interesting.

Gpt makes things up. It really shouldn't be used in technical discussions except for a catalyst to find something to look up.

They also taste like fish lol.

Most newsletters I receive do have that!

I know that the lampreys are often lumped in with the fish, but the jawed fish are more closely related to us than to lampreys.

(Fish aren't a clade at all so call em whatever you want.)

Phylogenetically, land vertebrates like us are fish too - we're descended from lobe finned fish.

So technically whales are fish, because all mammals are fish!

If not fish, why fish-shaped?

Only a fool would trust the output of GPT-5 for, well, any purpose.

Whales, like us, are descended from lobe finned fish, so they are as much fish as we are.

Wait what...Earthworms??

These eels undergo a notable sequence of transformations before their journey back to the sea. It wasn't until the 19th century that science connected the transitions from glass eel (larval form), to elvers, to yellow eel (freshwater adult), to silver eel (ocean spawning) form as members of the same species. Salmon are less mysterious as their spawning could be observed.

The directional bristles for anchoring to dirt (more noticeable on the larger earthworm species) are the remnants of polychaete parapodia. Similar to snakes that occasionally have remnant claws.

> Fungi and Animalia split from Eukarya. Fungi didn't exist before then.

Plants are also Eukaryotes but Fungi and Animalia have a more recent common ancestor than either has with Plantae.

We and fungi are both Opisthokonts, a distinct subclade of Eukaryotes, but plants are not.

https://en.m.wikipedia.org/wiki/Opisthokont

You should classify living beings according to a system that is helpful to understand and discuss the livings beings in a given context. "Fish" isn't a specific taxon in the standard biological taxonomy, but is rather a description of a specific set of common physical attributes and behaviors that is helpful to differentiate some organisms from other organisms. Regardless of official taxonomy, for 99.99% of people it's helpful to describe eels as fish.

I have extremely strong personal feelings about how confusing Google Maps can be about something eerily similar to this. For several years up until earlier this year, I lived in apartment in Brooklyn that (along with several other apartments) was in a building that happened to be above a deli. The address of the deli was the same as our apartments, but with no apartment number. However, the entrance to get into the apartments was past the end of the deli itself due to having a small lobby area on the ground floor containing the staircase leading up to the apartments, whereas the entrance to the deli was situated very slightly around the corner that it was on, enough that the door essentially looked to be facing outward diagonally in person, but showing up as slightly on the cross street side when looking at google maps. Because the addresses were so similar, we'd sometimes get mail intended for the deli, and I have to imagine some of our stuff sometimes went there.

Frustratingly, Google Maps only considered the deli entrance to actually be the location of our building, and the visualization it gave depicted entering through the door of the deli despite there being absolutely no way to go upstairs from there (even in the areas not accessible to customers; it was fully separated from the apartments themselves). Due to an unfortunate coincidence, an apartment building slightly further around the corner from us had an address with the same number on the cross street (making up numbers here, but essentially our apartment was 123 4th Ave, and the apartment around the corner was 123 56th St). Street View did not have any address shown when viewing the actual entrance of my apartment building; as far as Google Maps was concerned, that door did not belong to any building. Quite frequently, people seemed to trust Google Maps and assume that the entrance must be on the cross street. When we ordered food for delivery, it was not at all uncommon for the delivery people to ignore the instructions I put (which got increasingly attention-grabbing over the years, ending up with several repeated lines in all caps saying "ENTRANCE IS ON <the name of the avenue>" and "DO NOT GO TO <the name of the street>") and ring the doorbell of the apartment around the corner. Once, an entire desk was even delivered outside of that apartment building around the corner (which was quite annoying due to it being quite heavy and that building being downhill from the avenue). This culminated in our neighbor literally storming into our building with the delivery person to yell at me for being an "asshole" for not being able to do anything about this (although they of course had absolutely no interest in listening to anything I had to say, let alone any ideas I had about how we might be able to work together to get this handled better once and for all).

In the aftermath of that incident, I spent a lot of time trying to find ways to get Google Maps to properly show where the entrance of our apartment was. When I tried to contact their support to get this handled, I was informed that they only supported marking a single location as the entrance for a given address, regardless of apartment number (or the lack thereof), and that my only recourse would be to get the city to give my apartment building an entirely separate address. I asked for them to just slightly move the entrance marker over to be on the same street as the entrance to my building, with the rationale that people would still have absolutely no trouble finding the entrance to the deli since they'd be looking at the corner itself and it would be plainly visible, but it would no longer mislead people into thinking that they needed to enter on the cross street, but my request was ignored. I tried giving feedback within the Maps app itself saying that the location of the entrance was incorrect and suggesting a different pin, but unsurprisingly nothing ever seemed to change.

tl;dr Please do not blindly trust Google Maps as a source of truth for the location of an apartment building's entrance in Brooklyn; I have the emotional scars to prove it. (Probably a decent rule of thumb for other cities too, but I don't have firsthand experience anywhere else).

If you enjoyed this article then you must watch the A Capella Science music video on the same subject:

https://youtube.com/watch?v=TzN148WQ2OQ

By far the catchiest song about eel mating you will encounter today.

But literarily (not literally) they can be.

See also https://slatestarcodex.com/2014/11/21/the-categories-were-ma...

That's just silly.

Geese are molluscs.

Japanese style grilled eel is tastier than most other fish.

(Now I want unagi, and there's no late night sushi options where I am...)

What about the ones in New Zealand and Australia? https://en.wikipedia.org/wiki/New_Zealand_longfin_eel

Whales are fish that spout and have horizontal tail fins. (Currently re-reading Moby-Dick and that's the definition Ishmael comes up with.)

but were you signing up for a newsletter - or a subscription to a blog? it's a lot easier to make blog posts and then distribute them by email as well

all newsletters I've encountered that advertised as newsletter didn't have blogs, sadly :/

So that cucumber and tomato salad with vinegar dressing... is a fruit salad, as 100% of its ingredients are fruit or processed fruit. (As long as you leave off the onions).

The correct conclusion to take from this is that cladistics supremacists are wrong and there are other valid ways of organising knowledge.

I am; for a more serious take see [0].

    Now, there’s something wrong with saying “whales are phylogenetically just as closely related to bass, herring, and salmon as these three are related to each other.” What’s wrong with the statement is that it’s false. But saying “whales are a kind of fish” isn’t.

[0] https://slatestarcodex.com/2014/11/21/the-categories-were-ma...

Or humans are fish. You can pick one.

That is known today, but like I have said, the Ancient Greek and Roman authors, like Aristotle or Pliny the Elder, lumped together morrays and lampreys, because for some reason in the ancient world much more attention was paid to skin and limbs when classifying animals, than to the details of their jaws.

Because the Ancient Greeks and Romans used the same word for morrays and lampreys, when translating ancient texts it is difficult to decide which of the two was meant.

An entertaining read, but doesn't mention one of the weirdest things for me: eels essentially colonise the land. They don't just swim up rivers they get out and find their way into lakes and ponds that aren't connected to the sea by water at all. They can breathe air using their mouths.

I mean, in this case who else should do it? If a fish in your local waters goes from relative abundance to critically endangered, who else but the government is supposed to step in?

Japanese grilled unagi is amazing!

Of course whales are fish. Just look at them.

Of all the information in the Wikipedia article the fact that eels are fish was about the least interesting and only thing I previously knew.

It's right there in the intro section:

Longfin eels are long-lived, migrating to the Pacific Ocean near Tonga to breed at the end of their lives. They are good climbers as juveniles and so are found in streams and lakes a long way inland.

And Sigmund Freud spent some significant time researching Eel reproduction as it was a hot scientific topic at the time.

There was a book about the eels being born from Sargasso sea, all transparent at first, that I remember reading ages ago. It mentioned a lot of legends as well surrounding the eels, because the young ones were never seen - only fully grown eels.

I cannot remember precisely, but to explain their existence, there were even some recipes about "creating" eels. I think one was something similar to "put a couple of sticks under a bit of wet turf for a night". And that is how the witches were able to create the eels.

I wish I could remember the title of the book, but unfortunately it was more than 30 years ago when I read it.

"The Book of Eels" touched a lot of topics you mentioned, not sure about the witch bit though. It was published in 2020 so probably not the one you are looking for. https://www.goodreads.com/book/show/51938590-the-book-of-eel...

Where I live in Portugal glass eels are a seasonal delicacy (galeota/meixão). There is much confusion about the nature of this fish, as the same name is reused across the country, but I believe it is glass eel.

I don't like it and it seems to be going out of style with younger generations, which is good as its fishing is not sustainable.

Was it Waterland by Graham Swift (fiction, but has some eel diversions IIRC)?

my favorite online newspaper recently did a long form piece on eels and their decline in Italy ([1] - Italian only, sorry).

The comments mention a couple of books:

- Brian M. Fagan, Fish on Friday

- Patrik Svensson, The Gospel of the Eels (also wrote another book on eels)

maybe it's one of these two!

[1]: https://www.ilpost.it/2025/05/29/anguille-comacchio/

Thanks. I was wondering about how they got into lakes and bodies of water not connected to the sea.

Was hoping there was some secret underground tunnels connecting all bodies of water.

Thank you! Since you mentioned the decline of eels book that was in Italian, I finally remembered the title too since it wasn't in English neither. It was this book in Estonian: https://www.goodreads.com/book/show/17609869-angerja-teekond.

The title translated to English would be something like "The Journey of Eel" by Aadu Hint. Published in 1950, so I'm rather certain it makes more sense to read the newer books these days.

It's a brilliant title. I thought: huh, surely that's not a surprise? If that's a surprise, there must be more to eels than I know - which of course is what the article is actually about. If the title was just "eels have an interesting life cycle, actually", I probably wouldn't have realised how interesting it actually was.

I don’t mean to suggest that governments shouldn’t do things like this, I’m just abnormally delighted when I find them.

A multinational framework explicitly for the protection and restoration of eels would never have occurred to me (or most of the rest of humanity, I’d imagine) but nevertheless it occurred to someone and now there are civil servants who are paid real money to design and implement it.

To put it another way, I’m less interested in the policy than I am in the mechanics of governance that enable it to exist. One of my favorites is the National Cemetary Administration Operational Standards and Measures[1] program, which basically defines OKRs for U.S. veterans cemeteries.

1. https://imlive.s3.amazonaws.com/Federal%20Government/ID25151...

QI said (roll podcast title) There is no such thing as a fish, since that group is unbelievably diverse.

Strange that birds are dinosaurs, while Pterosaurs are not. Where is the bipedal fish that looks like a reptile or mamal, but is secretely a fish, too?

morray seems to be muscian, you mean moray

I’ve learned all sorts of strange facts about eels by doing crossword puzzles. EEL is a super common crossword answer. If the clue references some aquatic creature and the answer is 3 letters long, very likely the answer is EEL.

I think it's not about diversity, but lineage. The phenotype for "fish" is so tight and well defined; a salmon is closer related to a human in the tree of life than to a coelacanth even though both are categorised as "fish".

Eels were fish.

They will go extinct in XXI century. Most members of the family like the critically endangered European Eel are being eaten to extinction. Some studies claim that a 98% of the population of European eels alive in 1970, has vanished. Almost one of each two eels sold in USA as food belongs to this species.

Everybody were sharing recipes until the last one.

See (listen?) also the Radiolab episode https://radiolab.org/podcast/slippery-mystery

That's crosswordese for you - https://en.wikipedia.org/wiki/Crosswordese - there's also ERNEs, AUKs, TERNs and ORCAs out at sea

> out at sea

Surely you mean ASEA, my least favorite crossword non-word.

I think it's ok for there to be two meanings of "fish": a biologically formal (but not perfect) definition like I gave in my comment above, and a more informal meaning of "animal thing in the sea" that includes whales and even "starfish". It's very common for words to face more than one meaning. But that doesn't mean you can invalidate one by referring to the other.

Well, there are also legless salamanders, that look like eels pretty much.

https://en.wikipedia.org/wiki/Two-toed_amphiuma

Some of them have no lungs even:

https://en.wikipedia.org/wiki/Microcaecilia_iwokramae

So, it makes sense to say that eels are fish, because there are lungless eel-like creatures that are actually amphibians.

Same with lampreys. It was quite a surprise when I found one slithering around in my yard.

I think you got that comparison backwards.

A coelacanth is a lobe-finned fish which is the group from which tetrapods, and thus humans, evolved.

A salmon is a ray-finned fish which is a very different group. These groups diverged sometime around 300MYA.

> because the young ones were never seen - only fully grown eels.

Only, as it turns out, per the article the ones you normally see are _not_ fully grown eels; the sexually mature stage is also rarely seen.

My address used to be "Apartment 2, [Building], [Street]". There was also "Unit 2, [Building], [Street]" which was a bar in the same structure, but not particularly close to the entrance to the apartments. Google maps did... not deal well with this.

This was a surprisingly fun and captivating read.

I learnt this for my German fishing license. I was really baffled.

I don’t understand why you thought they weren’t fish. How is that possible?

Is it well know that there’s an issue with habitat risk in the Sargasso Sea? If not, then I don’t understand your comment.

Eels are weird as fk, and much of what they're up to is still a mystery from what I understand.

Turtles are reptiles.

How do they know where to go? How can they find Tonga or the Sargasso Sea unerringly in the vastness of the ocean?

Only cladistically. There's a better argument that there's no such thing as a tree or crab. As far as I understand, at least the common ancestor of all fish was still a fish.

I mean, do reptiles exist? Fish exist.

So politicians are reptiles after all?

> Only cladistically

"Only cladistically" is a bit like saying "only in reality" imo. :P

> As far as I understand, at least the common ancestor of all fish was still a fish.

Well.. eel-like probably more I'd guess. But yea.

The issue with "fish" is that people want it to be cladistic (trout and shark are fish) AND function (whales are not fish), and potentially also another anti-function (eels are not fish). You can't have it both/all three ways.

With crabs and trees that's 100% function, and that's fine imo.

> "Only cladistically" is a bit like saying "only in reality" imo.

In the sense that "imo" means "in my opinion, not necessarily in reality".

Clades are just a view on biology. It's not the only one. Otherwise, very few things in biology would exist.

> Well.. eel-like probably more I'd guess.

Still a fish.

The only people who want to see fish cladistically are the ones who don't want fish to be a thing. Fish are obviously a thing, and they are obviously not a clade. It describes function: water, gills, spine.

> eels are not fish

Many disagree.

I have multiple meanings of "fish", and that's ok.

But none of them include marine mammals such as seals, dolphins and whales. And none of them include penguins, even though penguins flying through the water on their little wings are impressively graceful and fast. None of these animals are fish to me under any meaning of the word.