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What a Fish Knows

The Inner Lives of Our Underwater Cousins

Jonathan Balcombe


An Observer Book of the Year 2017

A Sunday Times must read

New York Times Bestseller

Endorsed by His Holiness the Dalai Lama – ‘Balcombe vividly shows that fish have feelings and deserve consideration and protection like other sentient beings’

What’s the truth behind the old adage that goldfish have a three-second memory? Do fishes think? Can they recognize the humans who peer back at them from above the surface of the water? Myth-busting biologist and animal behaviour expert Jonathan Balcombe takes us under the sea, through streams and estuaries to the other side of the aquarium glass to answer these questions and more. He upends our assumptions, revealing that fish are far from the unfeeling, dead-eyed feeding machines so many of us assume them to be. They are, in fact, sentient, aware, social and even Machiavellian – in other words, rather 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. Teeming with insights and exciting discoveries, it offers a thoughtful appraisal of our relationships with fish and inspires us to take a more enlightened view of the planet’s increasingly imperilled marine life. What a Fish Knows will forever change how we see our aquatic cousins – the pet goldfish included.

  • Publication date: October 5, 2017
  • ISBN: 9781786072092
  • RRP: £9.99
  • Pages: 304
  • Publication date: December 1, 2016
  • ISBN: 9781786071231
  • RRP: £4.99
  • Pages: 304


‘Many of us have a soft spot for dolphins and whales, but Balcombe makes it embarrassingly clear how absolutely ignorant (and arrogant) we are when it comes to the vast world of our oceans and their inhabitants.’

Observer, Books of the Year

‘As cogent, salutary and substantial a study of piscine behaviour as I have read in years…This is a book full of wonders.’

Literary Review

‘Eye-opening…What a Fish Knows is far more than a mass of would-you-believe-it facts, marvellously entertaining though they are...passionate and persuasive.’

Sunday Times

‘Surprisingly, this compelling book is the first ever published that is devoted to fish behaviour.’

Forbes, 10 Best Popular Science Books of 2016



‘An extended exploration of the world from a piscine perspective...Balcombe makes a persuasive case that what fish know is quite a lot.’

Elizabeth Kolbert, New York Review of Books

‘...will leave you humbled, thrilled, and floored. Jonathan Balcombe delivers a revelation on every page, presenting jaw-dropping studies and stories that should reshape our understanding of, and compassion for, some of the most diverse and successful animals who have ever lived.’

Sy Montgomery, author of The Soul of an Octopus, a National Book Award finalist

‘We Buddhists consider all animals, including fish, as sentient beings who have feelings of joy and pain just as we humans do. We also believe that they have all been kind to us as our mothers many times in the past, and are deserving of our compassion. Therefore, we try to help them in whatever way we can and at least avoid doing them harm. In What a Fish Knows, Jonathan Balcombe vividly shows that fish have feelings and deserve consideration and protection like other sentient beings. I hope reading it will help people become more aware of the benefits of vegetarianism and the need to treat animals with respect.’

The Dalai Lama

‘[A] sparkling exposition on “our underwater cousins”…[and] a compelling pitch for greatly expanding fish conservation.’


‘As ethologist Jonathan Balcombe notes in this engrossing study, breakthroughs are revealing sophisticated piscine behaviours. Balcombe glides from perception and cognition to tool use, pausing at marvels such as ocular migration in flounders and the capacity of the frillfin goby (Bathygobius soporator) to memorize the topography of the intertidal zone.’

Barbara Kiser, Nature

‘Balcombe covers the waterfront, so to speak, from fish cognition and perception to their social structures and breeding practices, all the while drawing on a dizzying array of experiments and studies. In the hands of a lesser writer, the sheer weight of material could have overburdened the reader. But Balcombe’s prose is lively and clear, showcasing his gift for pithy sentences.’ 

Eugene Linden, American Scholar

‘With the vivacious energy of a cracking good storyteller, Balcombe draws deeply from scientific studies and his own experience with fish to introduce readers to them as sentient creatures that live full lives governed by cognition and perception…Balcombe makes 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.’

Publishers Weekly

Jonathan Balcombe

Author page

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