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4.6 · 863 Amazon ratings
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What a Fish Knows
What a Fish Knows by Jonathan Balcombe Review: A Myth-Busting Dive Into Fish Intelligence
Jonathan Balcombe's What a Fish Knows, a New York Times bestseller published by Scientific American / Farrar, Straus and Giroux, is a science-driven popular nonfiction work that systematically dismantles the idea that fishes are unfeeling, cognitively simple creatures, marshaling the latest ethological research to reveal their capacity for perception, feeling, thought, social bonds, and even tool use.
LuvemBooks Verdict
Best for
General readers — aquarists, anglers, marine conservationists, or anyone curious about animal cognition — who want an accessible but rigorously sourced introduction to the science of fish sentience and behavior.
Worth it if
Worth reading if you want a broad, well-organized survey of the latest ethological research on fish perception, feeling, memory, and social life, delivered with the narrative momentum of good popular science rather than a dry textbook.
Skip if
Skip it if you're seeking a purely descriptive zoological deep-dive on a single species or ecosystem — the book's sweeping scope across thirty thousand-plus species means individual topics receive limited space, and its closing sections are frankly conservationist rather than neutrally descriptive.
What readers & critics say
Literary Review called the book "cogent, salutary and substantial," describing it as "impressively rooted in science" and wearing its learning lightly, per literaryreview.co.uk. EcoLit Books found each section "more interesting and engaging than the last," judging it difficult to think of another title more important to the oceans and the earth's ecosystem, per ecolitbooks.com.
Sources: Literary Review, EcoLit Books, Scuba Scribbles, Reef2Reef, The StoryGraph4.6from 863 Amazon ratings— reader ratings, not a LuvemBooks score
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What a Fish Knows: The Inner Lives of Our Underwater Cousins by Jonathan Balcombe is a well-sourced work of popular science that systematically dismantles the notion that fishes are unfeeling, cognitively simple creatures, drawing on the latest ethological research to reveal their capacity for perception, memory, social bonds, tool use, and even pain. Critics praised Balcombe for combining the vivacious energy of a cracking good storyteller with deep scientific grounding, making the book accessible to general readers without sacrificing its research base. The key caveat: the book's closing sections are frankly conservationist in intent, so readers expecting a purely descriptive zoological survey will find the ethical advocacy more prominent than anticipated.
- Is it worth reading?
- For readers curious about animal cognition, marine biology, or conservation, What a Fish Knows is a compelling and well-sourced entry point — its New York Times bestseller status reflects genuine reach beyond specialist audiences. Critics credited Balcombe with making 'a convincing case that fish possess minds and memories, are capable of planning and organizing, and cooperate with one another in webs of social relationships,' and David Profumo in Literary Review called it a 'sparkling exposition.' The one real caveat is that the book's arc leads toward ethical advocacy in its final sections, which may surprise readers expecting purely descriptive zoology.
- Similar books
- Readers who enjoy What a Fish Knows will find natural companions in Ed Yong's An Immense World: How Animal Senses Reveal the Hidden Realms Around Us, which similarly uses the latest sensory research to reframe how non-human animals experience the world. Frans de Waal's Are We Smart Enough to Know How Smart Animals Are? covers overlapping territory on animal cognition with comparable scientific rigor. Peter Wohlleben's The Hidden Life of Trees: What They Feel, How They Communicate applies the same 'hidden inner life' framework to the plant kingdom, and Thomas McNamee's The Inner Life of Cats: The Science and Secrets of Our Mysterious Feline Companions brings a similar ethological lens to a domestic species. For readers drawn to the book's commitment to evidence-based thinking, Carl Sagan's The Demon-Haunted World: Science as a Candle in the Dark offers broader context on scientific skepticism and the dismantling of popular myths.
- Who should read this?
- What a Fish Knows is designed for general readers with an interest in animal cognition, marine biology, or conservation, and requires no scientific background. Aquarists, anglers, and marine conservationists will find its questions speak directly to their experience, as will anyone who has paused to wonder what the fish in a tank or stream might actually be experiencing. It is less suited to readers seeking a purely descriptive zoological reference without ethical dimension, or those wanting sustained deep-dives into a single species or habitat.
- About Jonathan Balcombe
- Jonathan Balcombe is an ethologist and author.
- What are the main themes?
- The book's central themes are animal sentience, cognitive complexity, and moral consideration — specifically as they apply to fishes, a group historically dismissed as unfeeling. Balcombe explores fish perception, memory, social bonds, cooperative hunting, tool use, deception, and pain, arguing that popular assumptions about fish intelligence and awareness are not just wrong but ethically consequential. A secondary theme is the gap between scientific evidence and public perception: the book systematically shows how breakthroughs in ethological research have outpaced the mainstream image of fishes as 'unfeeling, dead-eyed feeding machines.'
- Does it go deep or stay broad?
- What a Fish Knows is deliberately broad — it covers more than thirty thousand species across habitats from tide pools to the deep ocean, which is part of what earned it praise for showing the range and diversity of fish life. The trade-off, as the review notes, is that individual topics and ecosystems receive limited depth before the narrative moves on, which may frustrate readers seeking sustained focus on a single species group or habitat. The book is structured to build a cumulative argument about fish inner life rather than to serve as a reference work on any particular fish.
Summarize this book
Is it worth reading?
Who should read this?
About Jonathan Balcombe
What are the main themes?
Does it go deep or stay broad?
Summarize this book
What a Fish Knows is a popular science work by ethologist Jonathan Balcombe, published by Scientific American / Farrar, Straus and Giroux in June 2016, that argues fishes — more than thirty thousand species of them, outnumbering all other vertebrates combined — are sentient, socially complex, and cognitively sophisticated animals. Balcombe structures the book as a guided tour through fish perception, feeling, thought, social life, breeding, and suffering, tackling familiar misconceptions like the three-second memory myth and fish pain denial head-on with concrete field research. The book closes with a conservationist appraisal of how humans interact with fishes, grounded in a bibliography spanning pages 239–270 that gives readers a direct pathway into the underlying science.
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How is the book organized?
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Our Review
We review the evidence: published critics, reader verdicts and BookTube reviews, gathered and weighed with AI assistance and edited by LuvemBooks, rather than one reader's first-hand take.
A rigorous yet accessible work of popular science, What a Fish Knows makes a well-sourced case that fish deserve far more intellectual and moral consideration than they typically receive.
What the Book Actually Is and Argues
What a Fish Knows: The Inner Lives of Our Underwater Cousins is a work of popular science and animal behavior nonfiction by ethologist Jonathan Balcombe, published by Scientific American / Farrar, Straus and Giroux in June 2016. Its central argument is straightforward and deliberately provocative: fishes — more than thirty thousand species of them, outnumbering all mammals, birds, reptiles, and amphibians combined — are sentient, aware, social, and cognitively sophisticated animals, and the popular image of them as "unfeeling, dead-eyed feeding machines" is flatly wrong.
Balcombe structures the book as a guided tour through fish cognition and experience, with chapters organized around what a fish perceives, feels, thinks, and knows, as well as how it breeds and how it suffers. This architecture allows him to move systematically from sensory biology to social complexity, giving each dimension of fish inner life its own sustained treatment rather than bundling everything into a single catch-all argument.
Scope, Scale, and the Myth-Busting Mission
One of the book's defining features is the sheer breadth of the claims it takes on. Balcombe opens by targeting familiar misconceptions — the three-second memory myth, the assumption that fishes cannot recognize individual humans, the belief that they do not feel pain in any meaningful way.
The pain question receives particularly careful attention: as the book argues, fishes express pain in ways that differ radically from mammals, and that difference has historically been misread as absence. The book draws on breakthrough discoveries from researchers around the world to show that fishes conduct elaborate courtship rituals, form lifelong bonds with shoalmates, plan, hunt cooperatively, use tools, curry favor, deceive one another, and punish wrongdoers.
The publisher's description characterizes this portrait as worthy of "the grandest social novel" — a deliberate rhetorical choice that signals how ambitious Balcombe's reframing of fish life actually is. NoveList's catalog description credits Balcombe, who also wrote Second Nature, with challenging popular misconceptions through the latest understandings in animal behavior and biology.
Strengths: Storytelling Grounded in Science
Critical reception from major outlets points consistently to Balcombe's skill in combining scientific rigor with narrative momentum. Critics noted that Balcombe draws "deeply from scientific studies" while writing "with the vivacious energy of a cracking good storyteller," and credited him with making "a convincing case that fish possess minds and memories, are capable of planning and organizing, and cooperate with one another in webs of social relationships."
David Profumo, writing in Literary Review, described the book as a "sparkling exposition on 'our underwater cousins.'" These assessments align with the book's structural ambition: rather than presenting a single thesis and defending it, Balcombe ranges across tide pools, open ocean, and aquarium glass, examining how fishes gain knowledge of the places they inhabit and using specific field research and documented encounters to make each claim concrete.
The book includes a bibliography spanning pages 239–270, along with an index, signaling that the popular-science presentation is anchored in citable literature.
A Genuine Limitation: Advocacy Inflects the Analysis
The book's most honest limitation is also inseparable from its purpose. Balcombe is an ethologist who writes explicitly from a position of concern for fish welfare, and the final movement of the book — covering how fish suffer and Balcombe's "thoughtful appraisal of our relationships with fishes" — is frankly conservationist and ethical in intent.
Readers seeking a purely descriptive zoological survey, without the moral dimension, will find the book's arc leads somewhere more prescriptive than they may have expected. Some readers also find that the book's coverage, while broad across more than thirty thousand species, necessarily trades depth for range on any single species or ecosystem.
The ambition that makes it feel comprehensive also means individual topics receive limited space before the book moves on.
Who This Book Is For and Why It Matters
What a Fish Knows sits at a cultural and scientific moment when questions of animal sentience and welfare are genuinely shifting in mainstream discourse, and the book's New York Times bestseller status reflects the reach of that conversation beyond specialist audiences. It is designed for general readers with an interest in animal cognition, marine biology, or conservation, but requires no scientific background — the writing, as Publishers Weekly's assessment confirms, prioritizes accessibility without sacrificing the research base.
Aquarists, anglers, marine conservationists, and anyone who has paused to wonder what the fish in a tank or stream might actually be experiencing will find the book's questions speak directly to them. Its lasting contribution is less any single discovery than the cumulative effect of its argument: that fishes are participants in rich, cognitively complex lives, and that understanding this changes the ethical calculus around how humans interact with them.
Sources & Further Reading
The key facts and claims in this review are grounded in the retrieved, verified sources listed below.
- Cited in this review
- 1
- 2
- Further reading
- 3
Jonathan Balcombe, LuvemBooks
- 4
- 5
- 6
- 7
- 8
- 9
- 10
us.macmillan.com
- 11
Scuba Scribbles
Age & Reading Level
Recommended age
Adult
1 content note · who it suits
Content to know about
discussion of fish suffering and industrial fishing practices
Skip if you want a purely descriptive zoological survey without ethical advocacy or conservationist conclusions.
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