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What a Fish Knows: The Inner Lives of Our Underwater Cousins

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A New York Times Bestseller

Do fishes think? Do they really have three-second memories? And can they recognize the humans who peer back at them from above the surface of the water? In What a Fish Knows, the myth-busting ethologist Jonathan Balcombe addresses these questions and more, taking us under the sea, through streams and estuaries, and to the other side of the aquarium glass to reveal the surprising capabilities of fishes. Although there are more than thirty thousand species of fish—more than all mammals, birds, reptiles, and amphibians combined—we rarely consider how individual fishes think, feel, and behave. Balcombe upends our assumptions about fishes, portraying them not as unfeeling, dead-eyed feeding machines but as sentient, aware, social, and even Machiavellian—in other words, much like us.
What a Fish Knows draws on the latest science to present a fresh look at these remarkable creatures in all their breathtaking diversity and beauty. Fishes conduct elaborate courtship rituals and develop lifelong bonds with shoalmates. They also plan, hunt cooperatively, use tools, curry favor, deceive one another, and punish wrongdoers. We may imagine that fishes lead simple, fleeting lives—a mode of existence that boils down to a place on the food chain, rote spawning, and lots of aimless swimming. But, as Balcombe demonstrates, the truth is far richer and more complex, worthy of the grandest social novel.
Highlighting breakthrough discoveries from fish enthusiasts and scientists around the world and pondering his own encounters with fishes, Balcombe examines the fascinating means by which fishes gain knowledge of the places they inhabit, from shallow tide pools to the deepest reaches of the ocean.
Teeming with insights and exciting discoveries, What a Fish Knows offers a thoughtful appraisal of our relationships with fishes and inspires us to take a more enlightened view of the planet’s increasingly imperiled marine life. What a Fish Knows will forever change how we see our aquatic cousins—the pet goldfish included.

304 pages, Hardcover

First published June 7, 2016

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About the author

Jonathan Balcombe

12 books140 followers
Jonathan Balcombe was born in England, raised in New Zealand and Canada, and has lived in the United States since 1987. He has three biology degrees, including a PhD in ethology (the study of animal behavior) from the University of Tennessee, where he studied communication in bats. He has published over 45 scientific papers on animal behavior and animal protection.

He is the author of four books. Jonathon is currently at work on a new book about the inner lives of fishes, and a novel titled After Meat.

Formerly Senior Research Scientist with the Physicians Committee for Responsible Medicine, Jonathan is currently the Department Chair for Animal Studies with the Humane Society University.

Based near Washington, DC, in his spare time Jonathan enjoys biking, baking, birdwatching, piano, painting, and trying to understand his two cats.

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5 stars
1,198 (43%)
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425 (15%)
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Displaying 1 - 30 of 425 reviews
Profile Image for Petra X.
2,456 reviews35.5k followers
April 10, 2017
Years ago I had an extraordinary experience with squids when I was snorkelling off an unknown reef very close to a tiny island about 100 yards from shore. If the reef had been known there would have been very few parrotfish and cowfish, both of which are good eating. There would also have been no supermale parrotfish. A supermale is a female that has turned into a male and is double or more the size of the other fish and also much more beautiful and brightly coloured and absolutely delicious to eat.

So I was snorkelling and I saw a little squid, it stayed still in the water and was rapidly changing colour. Then it was joined by another, then another until there were about 7 of them of varying sizes from about the size of your hand up to forearm sized all in a row and all rapidly cycling colours. I called out to my ex to come and see but come slowly not to scare them. I didn't think they would stay. He swam over and by then there were about 11 squids and it was apparent to both of us that they were staring at me. They were as curious and interested in me as I was in them and they didn't go away for quite a few minutes. They were no more shy than I was and as I had called my ex, so they had 'called' each other. Perhaps it was because no one knows of the reef they live in they weren't frightened of people, I don't know.

What I learned from this book:

1. If we thought of fish as we do mammals we would stop thinking of them as 'other' and realise that they have the same five senses (plus more). Having the senses means using them and implies learning from experience (don't touch that sea urchin again, it not only stings, but poisons).

2. That people judge intelligence by how like us the animal thinks. We do too. All those books on animal intelligence are just about measuring how like us the animals solve problems that humans set them.

3. That scientists rail against anthropomorphising animals, but if we did a bit more with fish, if we were more empathetic and understanding we would see that they have personalities, liked to play and not pretend that they can't feel pain and have no consciousness so it's ok to come into my shop and say (as plenty of customers do) that they are 'basically vegetarians' but eat fish.

Here in the Caribbean, diving is good career. People come every week and want to be taken to see the reefs. The divers nurture relationships with generally-friendly fish like rays, giant groupers (Goliath fish) and some of the sharks so that their clients will have an interesting experience. Not all of these relationships are based on food. They never are with sharks. It would be foolish to feed sharks! But nevertheless, over years the divers and individual sharks get friendly and the sharks come and rub against the divers, much as cats do, and like to be caressed. What's in it for the fish is the same as what's in it for the people, it's entertaining, it's nice to see friends, what else could it be?

The book, to sum up, was quite boring. I was hoping for more than the author's conjectures based on our common senses, what is known about fish and their life cycles, and anecdotes (like mine). Few of his assumptions and conclusions were ones that were new to me. I don't think it's the fault of the author, it's just that fishes inner lives are mostly a mystery.

3.5 stars rounded up because the author did his best and at least opened a dialogue into the idea that fish are as deserving as consideration as other animals when it comes to protecting them from pain and harm.
Profile Image for Diane S ☔.
4,901 reviews14.5k followers
January 10, 2019
Who ever knew that s book about fish could be both so fascinating and illuminating. Don't think I will ever look at fish the same way again. So many characteristics that make us human do come into play with fish. Communication skills, empathy, using tools and other clever ways to get what they need, including cleaning. The chapters are nicely separated, covering a topic at a time.

So many different types of fish, I spent much time looking them up to see their pictures. Some can change from femsle to make, what a clever advantage. Some have elaborate courtships in order to attract a mate. My favorite little puffer fish for instance uses his fins, to create an unusual and elaborate sand circle, much like the crop circles in farmers fields. In the middle he further furnishes his new lady love with broken shells, seaweed, other types of bling. All this for one mating session. Intrepid little fella.

So many fascinating facts, well worth a read. Audio listeners be aware that illustrations are in the book. So many times the sudio does not contain a PDF file.
Profile Image for BookHunter M  ُH  َM  َD.
1,670 reviews4,539 followers
June 28, 2025

قبل عدة سنوات وجدني صديقي في العمل شارد الذهن أحدق في سقف الغرفة فبادرني قائلا:
- فيه حاجه و الا ايه
= ليس من السهل أن تكون ثعلب ماء
- نعم يا ضنايا
انفجرنا ضاحكين معا قبل أن أبرر له قولي العفوي الذي جاء بمنتهى الجدية رغم ما أثاره من جو كوميدي في المكتب بأكمله.
كنت قد شاهدت في اليوم السابق واثئقي عن حياة ثعلب الماء و المخاطر التي يتعرض لها من مفترسات أخرى أو من الإنسان و الطبيعة و خلال مواسم الهجرة أو التزاوج أو حنى في معاناة البحث عن الغذاء له و لأطفاله و في دفاعه عن نفسه و عن أسرته و منطقته. كان الفيلم جيدا جدا و مثيرا للتساؤلات عن هذه الحيوانات البحرية التي لا نكاد نعيرها انتباها و لكنها في النهاية أمم أمثالنا كما يقول التعبير القرآني.
لم يزل المعلق في الفيلم يقول عند كل موقف هذه الكلمة الشهيرة:
ليس من السهل أن تكون ثعلب ماء
و عندها أيقنت بالفعل أنه ليس أمرا سهلا بالمرة و عرفت أن هذا ليس هو الشيء الصعب الوحيد أن أكونه و عرفت أنه كم من ثعالب ماء و حيوانات أخرى تكافح من أجل البقاء.
إذا كنت مهتما بمراقبة الأمم الأخرى من بني الحيوان و تود أن تعرف أكثر عن سلوكها و طموحاتها في الحياة فهذا الكتاب هو بالتأكيد لك.
لن يسرد لك الكاتب معلومات مجردة عن الأسماك و أنواعها و تشريحها أو حتى وصفاتها بل سيخبرك بكل بساطة عن ما تعرفه السمكة التي نسيء فهمها و نتصور أنها كائن خالي من الإدراك و الإحساس و أن حياتها ميكانيكة تخلو من أي مشاعر أو أهداف و كل ذلك لأن وجوهها ككثير من الحيوانات تخلو من أي تعبير ناهيك عن غموض حياتها بالنسبة لنا لوجودها في ظلمات بعضها فوق بعض.
يخبرنا عن ما تدركه السمكة و ما تشعر به و ما تفكر فيه من واقع عشرات التجارب العلمية على أنواع كثيرة من الأسماك و ينتقل أيضا إلى موضوع غاية في التشويق عن من تعرفه السمكة. و هل الأسماك تستطيع التعرف على بعضها و على الكائنات الأخرى معرفة اجتماعية و كيف تتناسل السمكة و حياتها خارج الماء ثم يختم بفصل عن مخاطر انقراض الأسماك و الصيد الجائر و بشاعة مزارع الأسماك كسائر المزارع الحيوانية الأخرى.
Profile Image for Navi.
112 reviews216 followers
March 6, 2020
This is the most delightfully charming work of nonfiction I have read in a long time!

I have heard on numerous occasions that fish are nothing more than “water vegetables”, lacking feelings of pain, memory, familial love and social structure. They are continuously looked upon as a distinct species separate from the rest of the animal kingdom because they do not embody features we associate with more “sentient beings”.

I used to work in a Fish and Reptile department at a pet store. I have intimate memories of fish that recognized me when I came near their tank, liked to be touched, and had specific preferences with which fish they spend their time with. At the time, I thought it was all in my head and I was giving fish more credit than they deserved by anthropomorphizing them. However, there was always a lingering doubt in the back of my mind.

This book was a luminous revelation to me. The author's sincere passion and care for the welfare and advocacy of all "fishes" (instead of grouping them all together as a singular fish, the author makes a point of using the plural form to indicate that they are a group of individual fish with different likes, dislikes etc.) is embedded throughout the text.

Some interesting things I learned:

- Our assumption that fish are quiet is false. They make an array of different sounds to communicate with one another - one comical method is through (I kid you not) farting!

- There was a study exploring the relationship that Koi have with music. The researchers found that Koi correctly discerned different musical cues and were able to classify music by artistic genre (blues, classics etc).

- Fish are curious beings and gain stimulation through various modes of play. There is an anecdotal case where a cat and a fish play a running game with each other that was endearing. This is especially important for fish owners. I can’t imagine what a fish must feel living in an empty tank isolated without anything providing a source of entertainment or aesthetic comfort.

- The intricacies involved with the symbiotic relationship between fish and their cleaner were fascinating.

After reading this, I have a much deeper understanding and respect for our underwater cousins. I cannot recommend this book highly enough!
Profile Image for Wanda Pedersen.
2,223 reviews493 followers
March 19, 2018
Fish get short shrift when we are thinking about animal behaviour. Consider the poor maligned gold fish, which is reputed to have an attention span of mere seconds. Incorrect, as it turns out—gold fish can learn tasks and retain that learning for months.

I’m not a diver. I can’t swim and water will always be a scary place for me, but I can see where this book would be very interesting to anyone who spends time in the underwater world. Fish are much more interesting that I gave them credit for. I’m a birder, after all, and so I’m a little biased (although I certainly know that the term “bird brain” is actually more of a compliment than an insult).

It’s difficult for us to imagine what a fish’s life is like—they live in a completely different medium than we do, have extra senses that we can’t fathom, and have unexpressive faces. I think that last point is the one that leads us to underestimate fishes—we value expressiveness over evidence, I think, because it’s something we’re good at.

If you are interested in matters of animal intelligence (and human judginess) I would recommend Franz de Waal’s excellent book Are We Smart Enough to Know How Smart Animals Are?.
Profile Image for Lori Ann.
349 reviews5 followers
January 13, 2017
Brain candy for any diver...a must read.

The last two chapters point out a ton of inconvenient truths for fish eaters. Looks like there are going to be more nuts and beans in my diet.
Profile Image for Jenny.
1,177 reviews102 followers
March 15, 2019
"What many of these people like about fishes is not that they are like us. What is beautiful about them, and equally worthy of respect, is how they are not like us. Their different ways of being in the world are a source of fascination and admiration, and cause for sympathy. We can connect across the great divide that separates us, as when I have felt the gentle tugs of discus fishes rising to pluck food from my fingertips, or when a grouper fish approaches a trusted diver to receive caresses.

Among other things, fishes use their brains to survive and flourish, and one of the ways I have sought to raise the status of fishes has been to draw attention to their awareness and cognitive skills. But extolling the mental virtues of other species inflates the importance of intelligence, when intelligence really has little to do with moral standing... Sentience--the capacity to feel, to suffer pain, to experience joy--is the bedrock of ethics. It is what qualifies one for the moral community."
-"Epilogue"

This book is excellent. It taught me more about fishes than I'd ever expected to learn, and it is fascinating in the details Balcombe selected to share with his readers. What impresses me the most, other than the awesomeness and strangeness of creation expressed through fishes, is Balcombe's obvious love for and admiration of fishes. He makes them real to me through scientific evidence but also through anecdotal evidence. I appreciate that he mixes stories with science to not only prove his points but to also add sympathy and emotion to his arguments.

The main claim in this book is that fishes are not fish. They are not a mass of creatures without individuality, emotion, intelligence, or knowledge. They are individuals with personalities, memories, and culture. The way that fishes interact with each other, socially, sexually, and culturally is so similar to we humans that it makes it impossible not to see fishes as sentient beings, deserving of our respect.

Finally, I love the subtitle. For Balcombe, I know that it refers to evolution and the concept that life on our planet started in the water, and that at some point, our first land ancestors emerged out of the ocean and started developing bodies that could function on land. For me, it means that God created us all, so we all have common ancestry. Also, there was water before God created anything else, so in creation, the concept of life beginning in the water is the same as it is in evolutionary biology. Fishes existed before people, and they had more time to develop, evolve, and bond with the rest of creation. Why would we humans think we are any better than fishes? We have the same creator, and we are made from the same materials. We are all birthed from water.

I highly recommend this book to people who already love fishes but especially to people who are convinced that the things who live in water and don't blink are not intelligent individuals. You'll be shocked to find you are very wrong!
Profile Image for Tim Martin.
848 reviews53 followers
October 23, 2016
_What A Fish Knows_ was a quick, enjoyable read that veered between being a popular science book on the latest findings on fish behavior, memory, sensory abilities, and intelligence and a book strongly advocating for a kinder, more empathetic treatment of fish (and also essentially never, ever eating fish again). I can understand how one type of writing (fish are both surprisingly intelligent and quite aware of their environment and what happens to them in ways that might surprise most readers) would lead to the other (in the words of the author, “fishes are individual beings whose lives have intrinsic value – that is, value to themselves quite apart from any utilitarian value they might have to us,” very much echoing the views of _Relicts of a Beautiful Sea_ by Christopher Norment, who covered rare desert pupfish of the American Southwest at length, a book well worth reading). I rather preferred the more straightforward presentation of the latest findings on fish behavior and cognition than the more advocate aspects (most prevalent in the opening section and again towards the end), though even I cringed after reading the chapter at the end of the book describing the suffering and waste brought about by modern fishing practices (I am unsure if having read the book made that section even more cringeworthy, as I have always lamented so many things about modern fishing, such as the massive death of animals in the form of bycatch and the damage brought about by trawling nets).

I will admit that some of the more advocacy type claims made early in the book (such as on page 19, “we’ll explore how fishes are not just sentient, but aware, communicative, social, tool-using, virtuous, even Machiavellian” or on page 20 “[a]nother prejudice we hold against fish is that they are “primitive,” which in this context has a host of unflattering connotations; simple, undeveloped, dim, inflexible, and unfeeling”) made me think twice about reading the book but also, after reading it, deciding I was a bit too hasty, as the author did indeed provide examples of fish tool use, evidence of perhaps friendships among fish and among fish and non-fish, and lots of examples of Machiavellian behavior. It’s not that I thought fish were stupid or dim-witted or was surprised that they had some complex behaviors, but the more emotional aspects of what he wrote I was a little leery of (were the fish being anthromorphized or was this part of a philosophy that granted sentience to just about any animal and what did virtuous mean in this context?).

Another aspect of the book, which the author identified very early on, was his heavily reliance on anecdotes. While studies were definitely mentioned (and documented in the copious bibliography), there were lots and lots of examples, often provided by non-scientists, of fish behavior and intelligence indicating levels of cognition and recognition of individuals (be they other fish or non-fish like pet owners or individual divers) well beyond what most people would think of with regards to fish (a relevant quote on page 6, “I have sought to sprinkle the science with stories of people’s encounters with fishes, and I will be sharing some of these as we go along. Anecdotes carry little credibility with scientists, but they provide insight into what animals may be capable of that science has yet to explore”). They were fun to read and did indicate that so much more research can be done, but I sometimes found myself preferring the studies rather than the stories.

As far as the science of the book goes, most of it was fascinating. The author organized the book into different sections (“what a fish perceives,” “what a fish feels,” “what a fish thinks,” “who a fish knows,” and “how a fish breeds”), each section two or three chapters and filled with lots of fascinating facts.

The reader learns in the “what a fish perceives” section that some fish, such as bluegill, can see predators in a different part of the pond as they use the underside of the water’s surface as a mirror, that seemingly identical looking fish (such as various species of highly territorial damselfish) can distinguish between various individuals owing to distinctive facial patterns of dots and arcs only visible in UV, each pattern as unique as a human fingerprint, some fish (such as American shad and Gulf menhaden) can hear the ultrasonic sounds produced by predatory dolphins while others, such as cods, perches, and plaices, can hear infrasounds as low as 1 Hz, enabling the fish to migrate long distances using the ambient infrasound produced by waves, tides, and currents moving against cliffs, beaches, and reefs. Far from living in a silent realm, some fish have truly remarkable hearing as well as the mental ability to process it; one study with koi showed that the fish could even “discriminate polyphonic music [playing multiple notes simultaneously], discriminate between melodic patterns, and even classify music by artistic genre.” Not just eyesight and hearing are examined but also the sense of smell and electrorecption, the “biological ability to perceive natural electrical stimuli,” such as by electric eels (as an aside, I did not know that South American electric eels weren’t true eels at all but actually of the knifefish family, more closely related to catfish).

The section on fish sensory abilities was not terribly controversial and often backed up some common sense knowledge of fishermen and aquarium owners. The next section, “what a fish feels,” was a bit more, as it often went to heart of people saying that fish don’t feel anything, that they don’t feel pain, that when they look distressed from being handled or hooked it is just a reflex. Early on in the chapter, the author cautioned against “corticocentrism,” the idea that to “possess a humanlike capacity for pain” one must have a neocortex (though quickly acknowledging that few think birds don’t feel pain and also at the same time birds do not possess a neocortex). I feared that the section would be emotional or spiritual or the like (despite the solid science of the previous section), but again I was surprised at the series of very good studies on fish sensory capabilities and the solid science behind assertions that fish experience pain, react to it, and plan to avoid it in the future if possible. Also to my surprise the section didn’t just dwell on fish pain and stress but also fish joy, providing studies (and a lot of anecdotal examples) of fish experiencing joy and playing even as adults.

I think my favorite section was next, “what a fish thinks.” By this point I was swept away by some of the fascinating studies and anecdotes of the surprising mental abilities of fish. My favorite by far was the example of the frillfin goby (a fish of the intertidal zones of both eastern and western Atlantic shores). This fish prefers to stay safe in isolated tide pools at low tides, but when danger threatens it can leap with a high degree of success to neighboring pools. As studies showed, the fish does not sense these pools from its own pool, but remarkably “memorizes the topography of the intertidal zone – fixing in its mind the layout of depressions that will form future pools in the rocks at low tide – while swimming over them at high tide.” Also in this section the author demolishes popular conceptions of goldfish memories measured in seconds, provided an example of tool use discovered in 2009 (orange-dotted tuskfish near Palau using “rapid head-flicks and well-timed releases” to open clams against undersea rocks), showing how in one study vermiculate river stingrays in South America (a freshwater species) could problem solve to get food treats, even in several cases “moving away from a strongly attractive cue – the smell of food at one end of the tube [used in the experiment] – and trying the other side…not a trivial a thing…it means they have to work against their natural impulse,” and how archerfish (able to spray jets of water up to ten feet through the air to help them prey on insects) are able to get better at aiming not just from practice but actually watching other archerfish hunt, “a form of grasping something from the perspective of another.”

“Who a fish knows” was fascinating, going into aspects of fish sociology. The reader learns the differences between shoals and schools (shoals are groups of fish gathered together and socially interacting but each swim independently and may be facing different directions, while a school is more disciplined with the fish moving at the same speed and in the same direction at a fairly constant distance from one another). Another excellent section, the author covered predator inspection (behavior that lets a predatory fish know it has been spotted by other fish and highly suggestive it should move on) and two extremely interesting sections on cleaner fish and also on cooperative hunting (my favorite example being cooperative hunting between groupers and moray eels, with the groupers actually able to understand and have the moray eels in turn understand pointing, this accomplished by a grouper doing a headstand over a spot where a prey has hidden; this is a “referential gesture, which outside of humans, has only previously been attributed to great apes and ravens”). There was also coverage of fish culture, that non-inherited information passed on by “informed individuals” such as migration routes, ideal forage spots, which predators to avoid, etc. may be lost in overfished species and could be lost forever, complicating recovery efforts.

The last section, “how a fish breeds,” was much as I expected it, covering fish breeding, but was still interesting, covering the different ways fish are actually care givers and may protect eggs and young (the cichlids of the great lakes of east Africa get lots of attention) as well as elaborate gender hierarchies and courtship rituals. It included the latest research, such as the 2012 discovery of elaborate, geometric “crop circles” created by male pufferfish off the southern tip of Japan, huge mandalas up to six feet wide and decorated by shells, created by fish only five inches long.

The book closed (after a horrifying section on fishing) with another appeal that fish are deserving of empathy. “In those flat, glassy eyes we struggle to see anything more than a vacant stare...[t]heir unblinking eyes – constantly bathed in water and thus in no need of lids – amplify the illusion that they feel nothing.”

It was a good book and I am definitely glad I read it.
Profile Image for Sara.
235 reviews37 followers
December 19, 2017
Once I heard this book was coming out, I had to have it because, as the author points out, you can't really find an entire book devoted to fish ethology (behavior).

Now, this author undoubtedly has a bit of an agenda as you can tell from prior books. He's for animal rights so I wanted to see if he strayed too far from hyperbole. Generally I don't think he did. Mostly he stays with the science and makes some excellent points such as a) fish came way before us so it's not like they've stopped evolving for millions of years and b) fish reaction to pain stimuli and response to pain meds and some parallels to birds indicate they Can feel pain.

However, I do mostly maintain my initial ideas that yes... Fish feel pain and think but not to the degree of mammals. (He intimates that they feel acute more than chronic pain). The strong emotional component was even more spurious barring a few anecdotes.

That's not to say nothing surprises me though: the mental calculation and deception of certain fishes was surprising and very interesting (the cleaner fish chapter was great!) and the chapter on fish sensory adaptations was wonderful as well.

It was a really fun book and it does raise interesting questions on how to treat fish ethically. (I don't eat fish either). However, given the scope of the problems of overfishing, the author didn't give a ton of suggestions. An obvious one would be to explore Which fish are more sentient as people have suggested for apes and birds (macaws and the Corvid families) and maybe give them more consideration (he suggested wrasses but makes some points for chiclids too).

I would recommend this book. It will surprise and entertain you!
Profile Image for Montzalee Wittmann.
5,084 reviews2,313 followers
December 4, 2018
What a Fish Knows by Jonathan Balcombe and narrated by Graham Winton is a delightful and very informative book on fish. It explains how fish can feel pain, probably pleasure too, can plan, remember, scheme, communicate, and think! They have preferences, can be trained, seem to enjoy certain activities or people over others, and they use tools.
I am a vegetarian and I don't eat fish due to this reason but it is nice to hear the science behind it. I learned so much in here too! Wow! How different fish mate, communicate, use tools, and more!
In the end, the author discusses the fishing industry today...ugh!
I recommend this to anyone and everyone! So heartwarming all the things the little fish can do and no one seems to know about!

Profile Image for Katy Mann.
Author 7 books42 followers
October 5, 2016
Read this from a recommendation on a blog.

Did not know what to expect, but the book was a lively romp with an intelligent guide through all things fish. Senses, emotions, social structures.

Check it out.
Profile Image for أحمد فؤاد.
Author 8 books806 followers
August 5, 2020
ماذا تعرف عن عالم الأسماك؟ بالتأكيد قد شاهدت بعض الأفلام الوثائقية التي رأيت فيها أفلام مشوقة عنها، أو قد تكون قد من مرتادي الصيد، أو من مُحبي اقتناء أسماك الزينة. مهما كنت تعرف فتأكد أنك تعلم القليل عنه.

في كتاب ما تعرفه السمكة، يأخذك الكاتب في رحلة إلى العالم الأزرق حيث عالم المخلوقات المائية... الأسماك، خلال الرحلة نبدأ في التعلم أن ننظر إلى الأسماك ككائنات حيّة لها حياتها وقوانينها الخاصة، أغلبها لم نعرف عنها شيئاً من قبل، أما الذي نعرفه فالكثير منه معلومات مغلوطة، ولعل من أشهرها أن ذاكرة السمك ثلاث ثوانٍ.

الأسماك كائنات ذكية اجتماعية، تتعاشر وتتناسل وتخاف وتتألم وتهرب وتحارب وتقاتل وتفترس، عالم متكامل يحتاج إلى التأمل العميق في كيفية تعاملها مع بيئتها.

أسماك ترى بتقنية الأشعة تحت الحمراء في الظلام، بروتينات فسفورية،أسماك تلصق بيضها على جسمها ثم تبني طبقة الجلد عليه حتى يحين موعد الفقس فتزيله ليخرج البيض، أسماء ترى بكل عين مجال بصري مختلف في نفس الوقت.

حقائق مذهلة لا تملك أمامها إلا أن تدرك وتستسلم لعظمة وإبداع خلق الله تعالى.

لكن الكتاب في حزن في نهايته، عندما يُسلّط الضوء على تجاوزات الإنسان التي تؤدي إلى تدمير الحياة البحرية.

كتاب ممتع جداً ومثير للتأمل في إبداع الخلق.

تقييمي 5 من 5

وأترككم مع اقتباس من الكتاب.

لماذا لا نتعاطف مع الأسماك ؟

الأسماك دائمًا في مجالٍ آخر، صامتة وغير مبتسمة، عديمة الأرجل وميّتة العينين.

في تلك العيون المسطّحة الزجاجية، نحن نكافح لنرى أي شيء أكثر من نظرة محدّقة فارغة. لا نسمع أي صرخات ولا نرى أي دموع عندما تنغرز الأشواك في أفواهها وتُسحَب أجسامها من الماء. وعيونها التي لا تطرف - التي تُغسَل على الدوام بالماء وبالتالي لا تحتاج إلى جفون - تضخِّم الوهم بأنها لا تشعر بشيء. مع نقص المنبّهات التي عادةً ما تستحثّ تعاطفنا، نُصبح بالتالي لامُبالين لمحنة الأسماك.

إنّ ما نفشل في إدخاله في حساباتنا عندما يفتر تعاطفنا هو أنّ المخلوق الذي ننظر إليه هو خارج محيطه الملائم. إنّ الصراخ من الألم غير فعّال للسَّمكة في الهواء بقدر ما هو غير فعّالٍ لنا عندما نكون مغمورين بالماء. الأسماك مهيّأة لأن تعمل، وتتواصل، وتعبّر عن نفسها تحت الماء. العديد من الأسماك تُخرِج أصواتًا عندما تتألّم، ولكنّ الصوت الذي تنتجه ينتقل في الماء، ونادرًا ما نكتشفه. وحتى عندما نتمكّن من ملاحظة إشارات دالّة على الأسى - الرفرفة، التقلُّب، فتح وغلق الخياشيم لدى محاولة السَّمكة عيثًا أن تأخذ الأكسجين - فقد نتجاهلها كشيء لا يستدعي القلق، خصوصًا إذا اعتقدنا أنها مجرّد أفعال انعكاسية.


Profile Image for Wendy.
307 reviews6 followers
November 5, 2016
I gave this book 3 stars because I think the subject matter is so critical, but I have read some of Balcombe's other work and am left here with the same feeling as with those: the writing is slow, and only sporadically does it pick up into something really enjoyable. This is a shame. I am reminded of books I've read on animal rights, like There Is No Happy Meat and compare it to Jonathan Saffron Foer's Eating Animals - and though I much prefer the message of Bohanec's, it was actually Foer's that moved me much more (this after being vegan for some years when I first read it). I recently finished another book on animal behavior - Beyond Words by Carl Safina, and I am hard pressed to figure out the difference between his writing and Balcombe's. Could it be the way Safina takes his time and presents the worlds he shows? Could it be that he inserts himself fully into the information he shares? But Balcombe does the same, and I am much more aligned with Balcombe's thoughts and feelings; Safina sees problems and doesn't, say, stop eating salmon. Balcombe sees problems and tries to change them.

But from a writing and reading standpoint, I just found this one difficult to get through. I don't doubt Balcombe's science, and I am happy to have the information. It's just not a sit-down-and-enjoy kind of book.
Profile Image for Alina Rozhkova.
303 reviews19 followers
January 5, 2022
Замечательная книга, и рыбы тоже замечательные. В книге куча исследований о том, как рыбы себя ведут, как чувствуют, и почему не стоит их вылавливать и убивать в таком количестве.
В русском издании зачем-то миллион примечаний от переводчика и редактора, где они спорят со всем, что пишет автор, и приводят примеры всяких "русских способов приманивания сома" 🙄
Profile Image for Sille .
364 reviews92 followers
November 9, 2023
Väga hea raamat tuletamaks endale meelde, kui väär on lähtuda antropotsentristlikust vaatepunktist, nagu saaks mingit olendit intelligentseks pidada üksnes juhul, kui ta käitub ja mõtleb nagu inimene.
Siit raamatust saab kergesti loetaval, aga faktitihendal moel teada nii mõndagi sellest, mida kalad (tõenäoliselt kõige ekspluateeritum selgroogsete liik üleüldse) näevad, tunnevad, tajuvad, ja millest jääb mulje, et nad on eluks oma keskkonnas paremini ja mitmekülgsemalt varustatud ja ette valmistatud kui inimene oma keskkonna puhul.

"Kui kalad vaimujõudu nõudvates tegevustes primaatidest paremini hakkama saavad, tuletab see taaskord meelde, et aju suurus, keha suurus, karvkatte või soomuste olemasolu ning evolutsiooniline lähisugulus inimesega ei sobi intelligentsuse mõõtmiseks."
Profile Image for Jonathan Maas.
Author 32 books359 followers
April 9, 2018
An incredible array of fish facts that slowly work their way into a thesis

What a Fish Knows: The Inner Lives of Our Underwater Cousins, by Jonathan Balcombe is first and foremost, an incredible assortment of fish facts. Secondly, it is a book.

This is not to diminish it as a book - the incredible insight from the first gives it its power.

One of my favorite non-fiction books about the ocean is Deep: Freediving, Renegade Science, and What the Ocean Tells Us about Ourselves, where James Nestor acts as a writer/journalist first, and a diver second. Nestor goes to the widest array of the trope - and investigates the Ama, divers, dolphin researchers and everyone else.

Balcombe does not do this - he finds fish facts, and keeps at them until the reader gets the tale.

Again, this is not to his detriment - it's just his style is facts first, tale second.

In his spirit, I'll list some of his insights, and let you come to your own conclusions -

On the sheer number of fish
What we casually refer to as “fish” is in fact a collection of animals of fabulous diversity. According to FishBase—the largest and most often consulted online database on fishes—33,249 species, in 564 families and 64 orders, had been described as of January 2016. That’s more than the combined total of all mammals, birds, reptiles, and amphibians. When we refer to “fish” we are referring to 60 percent of all the known species on Earth with backbones.


On perhaps the root of our prejudice against fish
Among the vertebrate animals—mammals, birds, reptiles, amphibians, and fishes—it is the fishes that are the most alien to our sensibilities. Lacking detectable facial expressions and appearing mute, fishes are more easily dismissed than our fellow air breathers.

A great concept to try to understand things from an animal's point of view - it may be impossible, but at least you can understand what you are trying to do
One of my favorite concepts learned as a student of animal behavior is umwelt—a term created early in the twentieth century by the German biologist Jakob von Uexküll. You can think of an animal’s umwelt as its sensory world. Because their sensory apparatus varies, different species may have different perceptions of the world even if they inhabit the same environment.


On the fact that many fish just see more than we do
In the ages since, fishes have evolved visual capacities beyond our own. For example, most modern bony fishes are tetrachromatic, allowing them to see colors more vividly than we do. We are trichromatic creatures, which means we possess only three types of cone cells in our eyes and our color spectrum is more limited. Having four types of cone cells, fishes’ eyes provide four independent channels for conveying color information.


On an eel's sense of smell
But the champion sniffer among all fishes (as far as we know) is the American eel, which can detect the equivalent of less than one ten millionth of a drop of their home water in the Olympic pool. Like salmons, eels make long migrations back to specific spawning sites, and they follow a subtle gradient of scent to get there.


On the tastebuds of a fish
Taste buds are also more numerous in fishes than in any other animal. For instance, a fifteen-inch channel catfish had approximately 680,000 taste buds on his entire body, including fins—nearly 100 times the human quota.


In conclusion

And so on! I could go on and on - in short, if you want to know about fish in general, this is a good place to start. Even if you already know quite a bit, I'd give this a shot - you might get a lot!
Profile Image for Martin Smrek.
107 reviews31 followers
November 13, 2021
Great introduction into the complexity and depth of lives of fishes and into what science can tell us about their abilities to perceive the world around them and, of course, how close we are to telling whether fishes have counsciousness or not.
Profile Image for Perri.
1,484 reviews56 followers
August 4, 2021
We've learned so much about non human intelligence and sentience. Thinking or feeling differently than people just shows the incredible adaptations of species and may actually help us learn more about ourselves. I recently read The Hidden Life of Trees: What They Feel, How They Communicate – Discoveries from a Secret World, so why not fish? Probably because they live in such an alien environment from us. Their lack of expression and staring eyes seem, well, down rights fishy. Bur Balcombe makes a good case for them and helped me see them in new light. He also makes a convincing plea to stop the serious fish depletion from overfishing. This was a bit more dull than similar books I've read, but thought provoking for sure.
Profile Image for Siim Kala.
19 reviews1 follower
January 4, 2022
Senistest looma, putuka, linnu jne. raamatutest ehk kõige üllatavam, ilmselt seetõttu, et ootused kaladele ei olnud suured. Tegelikkuses ilmneb, et kalariigis on olemas vaste praktiliselt kõigile vaimsetele võimetele mis nii linnu kui loomariigis, kaasa arvatud primaatide võimed.

Raamat on tõesti infotihe ja lisaks ohtralt varustatud viidetega allikatele. Igati eeskujulik teostus.
Profile Image for Ben.
969 reviews118 followers
April 12, 2022
Full of factoids, logically organized, but the passionate scientists and the scientific process are mostly missing.

> Swordfishes can heat up their eyes twenty to thirty degrees Fahrenheit above the water temperature.

> The sticklebacks behaved as if they had previewed the study plan. When just one fish was presented with two models, it followed the healthier-looking model to its refuge about 60 percent of the time. Performance steadily improved with group size to over 80 percent in groups of ten sticklebacks. This is an example of consensus decision making.

> A subordinate male risks having to fight with a larger male if he is within about 5 percent of the bigger one’s size. A loss could bump him down a few notches in the mating queue. What is a little fish to do? In an admirable show of restraint, male gobies of various species deliberately limit their food intake to retain their place in the queue.

> If the breeding female dies, the chief male changes sex to female and the next largest fish in the subordinate group bumps up to chief male. So there is always hope for a suppressed male in a clownfish family. (All of this reveals a slight inaccuracy in the course of events in Finding Nemo. The fact is, upon Nemo’s losing his mother, his dad, Marlin, should have become his new mother.)

> sperm drinking certainly works for catfishes, for it is believed to occur in as many as twenty species.

> There are a few other all-female species among reptiles, amphibians, fishes, and birds. These species are referred to as parthenogenetic because no sperm is required to fertilize their eggs. But the situation is even more peculiar in Amazon mollies, because they can produce fertile eggs only if they mate with a male Molly of another species. Although the mating act is necessary to trigger pregnancy, it’s a case of “sperm donor lite” for males, whose sperm do not actually fertilize the female’s egg.

> Each leap culminates with the two fishes turning upside down and depositing sperm and about a dozen eggs. Talk about good timing! In this manner, several dozen translucent (and well-camouflaged) eggs end up adhering in a cluster on the target leaf. I’ve read that leaps can be four inches high, but watching a film of the behavior indicates that characins can jump much higher. They can also buy more time to deposit their goods by clinging to the leaf for several seconds. The incubation period is very short, which is just as well because Dad must work in overdrive to keep the eggs moist. He does this by firing water onto the egg masses with a skillful tail-flick. It must be an exhausting job, for splashing is performed at one-minute intervals during the two to three days until the eggs hatch and the newborns drop into the water.

> Pricklebacks, gunnels, and wolf eels coil their elongate bodies around their egg cluster as the tide recedes, trapping a small pool of water in which the eggs sit. It says something about the virtue of parental dedication that a fish will lie for many hours, exposed to air, to protect his or her future offspring. Further strategies for protecting eggs above the waterline include covering them with seaweed, burying them in the sand, and hiding them among rocks. There must be advantages: higher incubation temperatures, higher oxygen concentrations, and lower predation

> Some bettas protect their young in bubble nests, which might be an evolutionary precursor to mouthbrooding. Bubble nests work well in stagnant water where bubble-nesting bettas live. They keep the eggs and developing fry together, safe, moist, and close to the oxygen-rich atmosphere. But in moving water such as a stream, a bubble nest is very difficult to maintain. Parents manipulate eggs with their mouths during the construction of bubble nests, so it is just a short evolutionary hop to holding the eggs in the mouth.
Profile Image for Elizabeth.
1,081 reviews
December 10, 2018
In the history of persuasion no one has ever changed their mind while being talked at. Preaching is the quickest way to lose an unconverted audience. The best way to change someone's mind is to make them curious. Ask them questions and then calmly lay out your interesting facts. Then after you've let the evidence speak for itself you ask if the status quo should change. Does what you thought still seem true?
Sadly this book did the opposite. It started fast and hard condemning people's unfeeling, speciesist view of these poor creatures. Espousing cruelties and the author's own, lone kind heart. While I agreed with him on the folly of people classing fish as somehow less alive or more easily eaten than say cows, it is not just fish or the mamailian bias that I think of as strange. Life is life. Trees have memoirs, loyalties and language. We are land fish that can only survive outside the ocean by carrying the sea inside our bodies. These are facts. They awaken compassion and understanding, but they do so on their own with my telling you what you should feel.
If this book had just contained interesting, relatable facts about our fellow fish I would have enjoyed the whole thing. Alas, it did not, it was a sermon of why humans are unfeeling and biased. Yes, yes, I know that, I did not pick up this book to hear about people, I picked it up to learn about fish.
Profile Image for George Ilsley.
Author 12 books307 followers
July 20, 2024
Fish have been around for a very long time, and have apparently evolved many of the same features which mammals more readily demonstrate — or so Balcombe suggests in this fascinating book.

I admit being particularly interested in fish, being a fish hobbyist who breeds a number of nanofish for the aquarium trade. As a hobbyist, I was aware of the amazing variety in fish and their habits, such as livebearers, mouth breeders, bubblenest builders, and so on. However, the research in the book illuminates recent discoveries in fish consciousness, their social life and intelligence, tool use and planning capacities, parenting styles, and much much more.

Most fish are still unstudied, because of the challenges posed to observe them. Balcombe also raises the alarm about over-fishing, and habitat destruction, and this warning is particularly important.

Recommended for nature lovers, in and out of the water.
Profile Image for Sher.
543 reviews3 followers
January 10, 2019
What a sleeper! A surprisingly wonderful and engaging book about the life of fish. Did you know fish do have feelings, intelligence, use tools, plan, and have culture? Balcombe has that powerful combination as a writer to bring scientific studies alive, and we get lots of fascinating studies in this book presented in such a lively and clear manner. I also appreciate that Balcombe continually presents -well, this is another way we might interpret these results. And, unlike Sy Montgomery's books that I find to be simply too emotional. Balcombe is not overly sentimental. In fact the information and style is balanced. I've bought my friends copies of this book!
Profile Image for loonchies.
239 reviews25 followers
September 20, 2021

ชีวิตสัตว์ที่อาศัยอยู่ในน้ำมันมีอะไรต่างไป
ชวนให้ตั้งคำถามว่าทำไมมันถึงมีความสามารถบางอย่างนั้น
การวิวัฒนาการของปลาต่อมา การพัฒนาความสามารถต่าง ๆ ให้ใช้ชีวิตอยู่ในโลกใต้น้ำได้
เราเรียนรู้อะไรจากสิ่งเหล่านั้นได้บ้าง
อะไรที่เราคิดว่าใช่ แต่มันไม่ใช่ และมันไปไกลกว่าที่เราคิด
มองปลาแบบเลิกเอามนุษย์เป็นศูนย์กลาง มองโลกแบบถ่อมตัวเสียบ้าง
มนุษย์นี่ก็ทนงตัวเสียเหลือเกินและพยายามจะครองโลกและสร้างเรื่องฉิบหายมากมายก่ายกอง ทั้ง ๆ ที่ตัวเองก็ไม่ได้ดีเด่เลิศเลออะไรไปมากกว่าสิ่งมีชีวิตอื่น ๆ เลย

มุมมองต่อเรื่องต่าง ๆ แค่เปลี่ยนนิดเดียวทำให้เราจับจุดปัญหาต่างไปมากโขเลย
การเอาความเป็นมนุษย์ไปจับ แล้วศึกษาจากตรงนั้นต่อ บางทีก็ทำให้เราเสียเวลาหรือไปผิดทางในหลาย ๆ เรื่อง แต่มันก็น่าสนใจดีพอมองย้อนกลับไป ใช่ว่าองค์ความรู้เหล่านั้นจะไม่มีประโยชน์อะไรเลย มองจากตรงนี้ก็ทำให้เราเรียนรู้ที่จะไม่ยึดติดกับหนทางนั้น และมองหาวิธีการที่ต่างออกไปกับปัญหาอื่น ๆ ที่เจอในอนาคตได้ เพราะมุมมองปัญหาที่ต่างก็จะได้คำตอบที่ต่างไป
ยังมีอะไรรอให้เราศึกษาอีกมาก

กลับมาที่หลาย ๆ คุณสมบัติของปลาที่เราอ่านไปก็รู้สึกว้าว
ก็มาเจอความสร้างสรรค์ของสปีชีส์เราเองเนี่ย ที่เอาคุณสมบัติเหล่านั้นที่เรารู้มาประยุกต์ใช้ในการล่า/ควบคุม
ตบเข่าในใจ โลกมันมีหลายมิติเรื่องต่าง ๆ ก็มีหลายด้านสินะ
การล่าก็เป็นการประยุกต์ใช้องค์ความรู้อย่างนึง

ในแง่นึงเราเรียนรู้จะอยู่กับปลา ปลาเองก็เรียนรู้ที่จะอยู่กับเรา/กับสิ่งที่เราทำให้เปลี่ยนแปลงเหมือนกัน เพราะปลาเป็นมากกว่าอาหารและความรื่นรมย์
ปลาเองก็อาจจะเรียกร้องความสนใจจากมนุษย์ได้เหมือนกันนะ
I love adaptation

ประเด็นที่เรามองว่าน่าสนใจดี (สุดแสนจะน่าเอ็นดู):
* ปลาบางชนิดอาจจะคุยกันผ่าน”ตด”
* ความกลัวของแซลมอนกับกลิ่นขี้
* มิตรภาพของปลาทอง น้ำใจใต้น้ำ
* ปลาซึมเศร้าและกลไกป้องกันตัวเอง
* ปลาติดนวด & ปลาติดยา ~ ความปรารถนาและรื่นรมย์ของชีวิต
* ปลาบางชนิดอาจจะชอบเล่นกับแมว
* ปลาสุดเสือก ไปดู their saranaeness
* ปลาผู้จับนกเป็นอาหาร
* ปลาก็ตอแหลเพื่อผลประโยชน์ได้เหมือนกัน
* สำรวจธุรกิจทำความสะอาด&สปาของปลาน้อย กลวิธีการขายและโปรโมชั่น กลยุทธมัดใจลูกค้า และแก๊งต้มตุ๋นหลอกแดก (literally)
* ประชาธิปไตยในปลา หนทางเลี่ยง”ผนงรจตกม”
* สืบพันธุ์หรรษา: ไข่หลอก, ออรัลเซ็กซ์ของปลาดุก การผสมพันธุ์ผ่านหอยแมลงภู่
* หลากหลายวิธีฆาตกรรมปลาของมนุษย์ทั้งทางตรงและทางอ้อม ผลกระทบของการประมงต่อปลาและสิ่งแวดล้อม

…..

เขียนได้ดี อ่านไม่ยาก ไม่ได้วิชาการเกินไป นำเสนอรายละเอียดที่น่าสนใจแบบไม่รู้สึกเหมือนอ่านตำรา อ่านเพลินเลย

แต่ก็แอบมีส่วนที่เฉพาะทางชีวะเยอะอยู่ มีขยายความให้เล็กน้อยพอให้อ่านเข้าใจได้อยู่ แต่ถ้าให้เราอ่านเล่มนี้ตอนมัธยมก็คงจะเป็นเล่มที่ต้องใช้เวลาทำความเข้าใจอยู่เหมือนกัน

มีช่วงกลาง ๆ ที่เน้นไปที่เหมือนนำเสนองานวิจัยเกี่ยวแบบอธิบายง่าย ๆ แต่มามาติด ๆ กันแบบไม่มีอะไรมากั้นก็ลดอรรถรสการอ่านไปเล็กน้อยเพราะให้อารมณ์เหมือนอ่านตำรา ไม่เหมือนช่วงแรก ๆ ที่กลมกล่อม จังหวะการอ่านกำลังดี หลัง ๆ เริ่มเป็นเรื่องเล่าจากการสังเกตละ

มีจุดที่เราอ่านแล้วนึกตามยากหน่อยคือเวลาพูดถึงปลาประเภทต่าง ๆ ถ้าเราไม่รู้จักเราก็นีกภาพไม่อออก ต้องไปเปิดหา แล้วเล่มนี้ก็พูดถึงปลาหลากหลายชนิดมาก หยุดอ่านเป็นช่วง ๆ

โดยรวมคืออ่านสนุกได้รู้อะไรหลาย ๆ ด้านเกี่ยวกับปลาที่ไม่เคยรู้มาก่อน
Profile Image for Daniel M..
Author 1 book32 followers
September 10, 2017
When we seem them, they’re all a “fish out of water..,” which is a phrase describing someone in an alien place, probably suffering as a side effect. That’s 99% of our experience of fish, but it’s not Balcombe’s experience, and he wants us to know that fish have interesting cognition (learning and performing complex tasks), sophisticated memories, relationships, social bonding, and a real sense of pain that we continuously violate.

The book tells us that fish have these rich lives, but we don’t understand them because they’re so alien to us. Without a leg to stand on, literally, or a face to express emotion, or even voices with which to scream, understanding fish requires some sympathy and a deeper understanding that we normally give them. Usually, our experience of fish is a protein on a plate. But they are much more than that.

In seven chapters, the book gives the view that we are incredibly species-ist about understanding animals in general, and fish in particular.

Chapter 2—what a fish perceives: They see, touch, and sense a rich underwater world in ways that we can’t imagine. What would it be like to have taste buds all over your body, or see the electrical fields of other animals, or feel every tiny passing pressure wave. We feel air pressure when it’s large enough—but imagine feeling every passing breeze at 100X the resolution, or hearing sounds of other fishes pressure wave as they pass by.

Chapter 3—what a fish feels: Unlike what your grandfather might have told you, a fish definitely feels pain. That hook in the mouth hurts. But it’s worse to but hauled up in a net from 1000 fathoms down, crushed together with a million of your kind, crushed, suffocated, and decompressed with your guts coming out of your throat. We can’t pretend this isn’t just slaughtering creatures that don’t feel pain.

Chapter 4—what a fish thinks: Much to my surprise, fish have a lot more intelligence (and long-term memory) than I’d thought. It’s not just clever skills, but also learning by observation of others behavior (perspective taking), planning out future actions, and remembering skills and patterns for a very long period. There are fish that engage in inter-species social communication, along with temporary upsets, fights, and reconciliation. (Yes, there are even fish that are tool users, which is quite a feat without fingers or hands.)

Chapter 5—Who a fish knows: Yes, they have social intelligence as well. They have friends, they mourn the loss of a companion, and even organize hunting parties together. Certain groupers even use referential gestures to point out where food is hiding for a moray. The eel sees the grouper “pointing” at the food (with his whole body), rushes in for the kill, and the grouper benefits by cleaning up the leftovers. That is, the grouper is signaling to his hunting partner, “there’s a fish hiding in here.. go get him!” This is all very much more than I ever would have expected of a fish.
Chapter 6—how a fish breeds: I thought I knew a lot about the variety and depth of fish mating and fish-rearing behavior, but since I last read about this, research has shown even more remarkable insights. Yes, there are remarkable swimming displays to attract a mate, and there are amazing constructions that fish will build (without hands!) to show off their prowess and fitness for mating. But there are novel reproduction methods I didn’t know about. Example: the female armored catfish (Corydoras) attaches herself to the genitals of the male to drink his sperm (who knew they had oral sex?), BUT it’s not digested, but pass through her body in seconds to be carefully excreted atop her clutch of just released eggs. (Which means she has a special “pass-through” mode for things she ingests, and not digests.)

It goes on and on: fish that deposit their fertilized eggs inside of a mussel for safe harbor and development until the fish are born, and leave the borrowed bivalve womb.

Since sex and mating drives a lot of behavior, it’s no surprise that it drives fish behavior as well. Male Atlantic mollies have a gonopodium (which looks and functions a lot like a penis) that they use to mate. The males also practice deception—they will show a false interest in a smaller female (which then attracts other males to the smaller female), and the largely endowed gonopodium male will then run off with the larger (and more attractive) female.

(And, in an interesting twist, there are mollies that live in the Amazon that are (appropriately enough) all female. BUT, they can produce viable eggs only if they mate with male mollies… of a different species. They mate and generate eggs, but the eggs aren’t fertilized by the spermatic contribution of the other-species male. It’s a case of “immaculate deception.”)

Equally amazing, some female fish take care of their young post-birth. Some go so far as to excrete a special kind of immunity-boosting mucus from their scales, which the little fry are encouraged to eat. Like mammalian mother’s-milk, the fish-mother’s mucus is early stage, specially adapted food for the infant fish.

Overall, “What a Fish Knows” is a beautifully written paen to fishes, and a call for humanity to stop the killing of an entire category of sensing, perceiving, attentive animals.

Fish are the only wild “bush meat” that we consume on a massive, industrial scale. Yes, there are farmed fish, but that has its own set of problems. Not only are we being cruel about the way we capture them, but we’ve destroyed many populations along the way. That orange roughy you had with a light cream sauce was probably 100 years old when caught. Since orange roughy are slow-growing and late to mature, this means they have very low resilience, making them extremely susceptible to overfishing. Likewise for sharks, cod, etc etc etc.

Would we do anything differently if cows took 100 years to mature to edibility? But because the orange roughly lives in the deep sea at 1000 meters down, we don’t see this, and we don’t know what’s really going on.

What’s worse, it’s become clear that some fishes have cultural knowledge that’s passed down between generations (primarily around good breeding places). It’s very possible that some kinds of fish are not bouncing back after fishing is halted because they’ve FORGOTTEN how to have a viable population.

There’s a lot more going on with fish than you might have known.

It’s enough to make you stop eating fish. I’m certainly decreasing the amount and kind that I eat.

Profile Image for Charlene.
875 reviews684 followers
February 16, 2019
Interesting facts about fish:

Do fish feel pain? It seems that they do. If you expose fish to a pain condition, such as exposure to vinegar, they cannot complete their task. However, if you give fish pain medication, they can complete the task, despite the vinegar exposure.

Fish express anxiety over a variety of things (e.g. finding the correct shelter). Researchers observe various fish doing various tasks and identify the anxious fish, give the fish anxiety meds, and observe that they are less anxious and can make better decisions - the decisions non anxious fish make.

Large fish have spa days. They go to cleaner fish stations to get cleaned, mostly of parasites. They observe the cleaners to see who is an honest cleaner and who is a non honest cleaner (honest = little or no biting of the precious mucus that covers the large fish's skin/ dishonest = taking tasty bits of the mucus skin). Just as humans use Yelp or Google to rate businesses, cleaner fish seem to get reputations as honest or dishonest. Honest cleaner get more clients.
When being cleaned, if the large fish senses danger, it will open its mouth and chomp down, trapping the small cleaner fish inside. After the danger passes, the large fish will open up and allow the cleaner fish to swim free.

Some fish love to be petted, just as a dog enjoys it. The author thinks this is worth studying. Do they experience pleasure? He wants to find out.
Profile Image for hania ಇ.
323 reviews41 followers
July 5, 2025
every tongue that rises against fishes shall FALL
“But a lion has a lot more charisma than a lionfish. I believe that the main source of our prejudices against fishes is their failure to show expressions that we associate with having feelings…In those flat, glassy eyes we struggle to see anything more than a vacant stare. We hear no screams and see no tears when their mouths are impaled and their bodies pulled from the water. Their unblinking eyes—constantly bathed in water and thus in no need of lids—amplify the illusion that they feel nothing. With a deficit of stimuli that normally trigger our sympathy, we are thus numbed to the fish's plight.

What we fail to account for when our sympathies falter is that the creature we are regarding is out of its element. Crying out in pain is as ineffective for a fish in air as crying out in pain is for us when we are submerged. Fishes are rigged to function, communicate, and express themselves underwater. Many do vocalize when they are hurt, but the sounds they produce evolved to pass through water, and rarely do we detect them. Even when we can notice signs of distress flipping, thrashing, gills opening and closing as the animal tries in vain to take in oxygen—if we are schooled in the belief that they are just reflexive, we may shrug it off as nothing to be concerned about.”
Profile Image for Sketchy_tunes.
194 reviews6 followers
August 12, 2022
|5,0*|
What a great book! It’s amazing how much you learn about fish by reading this book. It’s fascinating and eye opening and at the same time horrifying if you consider what we do to these intelligent, emotional and often social animals.

The author writes in a very human and tangible sort of way while still giving so many studies and scientific findings that you just cannot dismiss the points he is making. He incorporates humour and anecdotes into the text which makes it far easier to read but I have to say it is still a very dense book and one might consider reading it bit by bit.

I highly recommend this book to anyone but especially to those who think “it’s ok to eat fish ‘cause they don’t have any feelings”.
Profile Image for Kristin.
204 reviews
February 26, 2022
Well organized, mostly common sense at times, but still sprinkled with interesting facts. The intro comes on a little strong with the author’s personal opinion, but it gets more scientific after that.
Profile Image for Christian Orr.
414 reviews34 followers
April 26, 2018


Not only are we learning from other scientific studies that birds are (and dinosaurs were) much more intelligent than longstanding paradigms had assumed for so many decades, this fascinating book shows that the same is true of fish as well; their cold, seemingly robotic and unfeeling automaton appearance notwithstanding, their actually sentient beings with intelligence and even personalities. The author offers his evidence with plenty of solid science, with detailed information backed by a witty writing style.

The author injects some bleeding-heart liberal politics at several points in the book (not just in the animal rights arena but also a totally irrelevant interjection at one point on gender identity politics), which brings my rating from 5 stars down to 4.....but at least, unlike many animal rights and environmentalist extremists, he doesn't advocate the total abolition of fish consumption; rather, he brings up some valid concerns about overfishing (i.e. excessive depletion of a precious, valuable resource) and about the need for more humane methods of killing fish intended for human consumption.

RANDOM STREAM OF CONSCIOUSNESS NOTES AND OBSERVATIONS (and noteworthy passages)

--"One author, Alison Mood, has estimated, based on analysis of Food and Agriculture Organization fisheries capture statistics for the period 1999–2007, that the number of fishes killed each year by humans is between 1 and 2.7 trillion.*" Funny, most people don't talk about "killing" fish that they catch like they would talk about "killing" mammals and birds that they hunt.

--"dizzying numbers like these tend to mask the fact that each fish is a unique individual, not just with a biology, but with a biography. Just as each sunfish, whale shark, manta ray, and leopard grouper has a distinctive pattern from which you can recognize individuals on the outside, each has a one-of-a-kind life on the inside, too. And therein lies the locus of change in human-fish relations. It is a fact of biology that every fish, like the proverbial grain of sand, is one of a kind. But unlike grains of sand, fishes are living beings. This is no trivial distinction. When we come to understand fishes as conscious individuals, we may cultivate a new relationship to them. In the immortal words of an unknown poet: 'Nothing has changed except my attitude—so everything has changed.'" Profound.

"According to FishBase—the largest and most often consulted online database on fishes—33,249 species, in 564 families and 64 orders, had been described as of January 2016. That’s more than the combined total of all mammals, birds, reptiles, and amphibians. When we refer to 'fish' we are referring to 60 percent of all the known species on Earth with backbones." Mind-blowing stats.

--"Bony fishes, scientifically termed teleosts (from the Greek teleios = complete, and osteon = bone)," I thought they were termed Ostichthyians?

--"The bony fishes are at least as evolutionarily distinct from the cartilaginous fishes as mammals are from birds. A tuna is actually more closely related to a human than to a shark, and the coelacanth—a 'living fossil' first discovered in 1937—sprouted closer to us than to a tuna on the tree of life. So there are at least six major vertebrate groups if one counts the cartilaginous fishes." Wow, thought-provoking, and dare I say (borderline) paradigm-shifting?

--"In any event, brain size is only marginally meaningful in terms of cognitive advancement. As the author Sy Montgomery notes in an essay on octopus minds, it is well known in electronics that anything can be miniaturized. A small squid can learn mazes faster than dogs do, and a small goby fish can memorize in one trial the topography of a tide pool by swimming over it at high tide—a feat few if any humans could achieve." And to use a mechanical & technological analogy, look at microchips and microprocessors vs. older and bigger vacuum tubes.

--"As far as we know there is only one way to achieve internal fertilization: sex with an intromittent organ. So it appears that fishes were the first to enjoy 'the fun kind' of sex. About this discovery and John Long, the Australian paleontologist who brought it to light, [David] Attenborough expressed ambivalence during a public lecture: 'This is the first known example of any vertebrate copulating in the history of life … and he names it after me.'" Ha!

--"fishes are not easily fathomed." Pun intended?

"A seven-month survey using echo soundings of the mesopelagic zone (between 100 and 1,000 meters—330 to 3,300 feet—below the ocean surface), published in early 2014, concluded that there are between ten and thirty times more fishes living there than was previously thought." Fascinating revelation.

--"In exchange for the male being the ultimate couch potato, the female never has to wonder where her mate is on a Saturday evening." Haha, amusing metaphors/analogies.

--"Frilled sharks carry their babies for over three years, the longest known pregnancy in nature. I sure hope they don’t get morning sickness." Haha, this author sure is witty.

--"Speaking of superlatives, and names, surely one of the longest belongs to Hawaii’s state fish, the rectangular triggerfish, known by the locals as humuhumunukunukuapua’a (translation: the fish that sews with a needle and grunts like a pig). Perhaps the award for least flattering name should go to an anglerfish dubbed the hairy-jawed sack-mouth, and for most preposterous to the sarcastic fringehead. For the title of crudest, I nominate a small coastal dweller, the slippery dick (Halichoeres bivittatus)." A literal limp wet fish, the latter species? Nyuk nyuk?

--"In March 2015, scientists described the first truly endothermic fish, the opah, which maintains its body temperature at about 9 degrees Fahrenheit above the cold waters it swims in at depths of several hundred feet,"

--"There isn’t anything musical about the sounds that herrings make, but their innovative method might warrant a fish Grammy Award. One paper describes the first example of what might loosely be termed flatulent communication. Both Pacific and Atlantic herrings break wind by releasing gas bubbles from the anal duct region, producing distinctive bursts of pulses, or what the research team playfully named Fast Repetitive Ticks (FRTs). A bout of FRTs can last up to seven seconds. Try that at home! The gas probably originates in the gut or the swim bladder. It isn’t clear how these sounds function in herring society, but since per capita rates of sound production are higher in denser schools of herrings, a social function is suspected. So far there is no evidence that herrings ever beg your pardon." Heh heh, I gotta share that one with Dave Writer!

--"Male deep-sea anglerfishes illustrate the interplay of senses. **They have the largest nostrils relative to head size of any animal on Earth**, according to Ted Pietsch, the world’s go-to guy on anglerfishes." [emphasis added]

--"Consider also that the elephantfishes have the largest brain cerebellum of any fish, and that their brain-to-body-weight ratio—a highly touted marker of intelligence—is about the same as ours."

--"perceptions of fishes, I received unsolicited accounts from eight of a thousand random respondents who described behavior like that of the Midas cichlid we just met. These fishes would allow their humans to pet, touch, hold, and stroke them."

--"'To suggest that fishes cannot feel pain because they don’t have sufficient neuroanatomy is like arguing that balloons cannot fly because they don’t have wings.' Or that humans cannot swim because they don’t have fins."

--"Tool use was long believed unique to humans, and it is only in the last decade that scientists have begun to appreciate the behavior beyond mammals and birds."

--"Aquariums illustrate what science demonstrates: fishes have social lives."

--"Creatures like Grandma and The Whisperer defy the common prejudice that sharks are terrorists and bony fishes primitive and dull. Natural selection acts on variation across individuals, and for complex creatures with minds and social lives, personality is an expression of that variation. You don’t have to have fur or feathers to have personality; scales and fins will suffice."

--"Roving coral groupers and their close relative leopard coral groupers use a “headstand” signal to indicate the location of hidden prey to cooperative hunting partners of several types: giant moray eels, humphead wrasses, **and big blue octopuses**." **emphasis added** Wow, even cooperating with non-fish, non-vertebrate species, i.e. cephalopods!

--"The clever science writer Ed Yong summed it all up with a piece titled 'When Your Prey’s in a Hole and You Don’t Have a Pole, Use a Moray.'" Haha, good one.

--"Hans and Simone Fricke, who studied this strict mating system, described the low-ranking males as being, in essence, psychophysiologically castrated." [regarding clownfishes] Egad!

--p. 183: Oh, good Gawd, not the human gender reassignment/gender identity debate! Not germane to the book topic at all! Ugh, the author's lost me now!
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