Fish Sense

by Jonathan Balcombe

A quirky, intimate, and eye-opening look into the ways of thinking like a fish.

An extract from the much-loved modern classic on the subject of fish consciousness, What a Fish Knows.

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? Jonathan Balcombe dives in among our marine cousins to explore the essential questions of how fish perceive and process the world.

With his ethologist’s gift for showing us the hidden depths of questions we’ve routinely preferred to think of as simple, and his raconteur’s flair for the surprising and the curious, Balcombe takes us under the sea, through streams and estuaries, and to the other side of the aquarium glass to reveal the surprising capabilities of fishes. 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.

Using humor and a repertoire of some of the most surprising fish facts you’ve ever heard, Balcombe shakes up what you think you know about what’s going on inside the mind of these denizens of the deep.

Fish Sense is part of the Picador Shorts series “Oceans, Rivers, and Streams” in which excerpts from beloved classics speak to our relationship with our water bodies, great and small.

Genres: Nonfiction

144 pages, Paperback

Published June 10, 2025

About the author

Jonathan Balcombe is a British-born ethologist, editor, and author known for his work on animal behavior, sentience, and the human-animal relationship. Raised in New Zealand and Canada before settling in the United States, he studied biology at York University and Carleton University before completing a doctorate in ethology at the University of Tennessee, where he researched vocal communication in Mexican free-tailed bats. Balcombe has worked with several animal protection organizations, including the Humane Society of the United States and Physicians Committee for Responsible Medicine, and later served as Director of Animal Sentience with the Humane Society Institute for Science and Policy. He has written influential books including Pleasurable Kingdom, Second Nature, The Exultant Ark, and What A Fish Knows, blending scientific research with accessible storytelling about animal cognition and emotion. Alongside publishing scholarly articles and lectures worldwide, he has remained active in advocacy for animal welfare, conservation, and veganism for decades.

Reviews

[Phillip Mayer · Rating 5 out of 5]

I realize I’ve just been rambling up to this point. I might copy and paste this paragraph back at the top for anyone who is actually curious about the book and not just entertained by my mad rambling. For context, this was written at 5:32 PM on June 6, 2026, but is getting thrown back to the top.
Honestly it’s a little eye-opening. It’s a cool book to pick up if you’re just curious about marine bio, but it describes the studies in each chapter in such a way that lends itself to. . . . trying to think of a word that goes beyond “contemplation,” but I guess I’ll just say it has layers beyond that. For me at least, but y’know.
It’s like 100 pages I could’ve finished it in an afternoon but I didn’t and I don’t regret it because I actually enjoyed having it on my desk and in the back of my mind for the better part of a year. Then I went and spilled wine on it so it has scars but it did survive.

June 5, 2026, ??? o’clock
Gonna give a disclaimer that this is written under the influence.
Also, disclaimer that this will be long and will not be proofread (by me at least but if you wanna send me back a markup I think everyone who follows me on here has my email).
Doubling down on the previous disclaimer. I reeeeaaalllyyy feel a need to write right now, so this will be kind of ridiculously long.
Lets talk about fish.
There’s a bit in the book that I read about a year ago, but still sticks with me. There were these two beta fish that were kept together in a researcher’s tank. They generally ignored each other, except to compete for food when feeding time came. Then, one of the beta fish got stuck in a tank decoration and was thrashing around to get out. The other one, typically ignorant of the other’s existence, was slamming into the decoration to help the other. The researcher noticed in time to just help the two of them. Strangely, after the

June 6, 2026, 7:56 AM
Sorry I got hungry midsentence, ate, fell asleep, and then got back up and wrote this sentence in the morning. I’m really just letting you all experience my stream of consciousness with this review. I’ve got some stuff to take care of. I’ll be back soon, probably inebriated again.

Actually, while I still have a somewhat clear mind, I’ll briefly explain that this book is roughly 100 pages long. I read the first 75 last August, and finished the last 25 around a week and a half ago. If the review is incoherent, yes blame the chemical influence, but also blame the flow of time and my capacity to remember things. Alright, seriously, stuff to do, I’ll be back.

June 6, 2026 5:11 PM
Well that was awful.

Anyway, we’re back to talk about fish. Ok so after the one was released from the decoration, and the other tried to save it, they suddenly became buddies??? Like, what??? They started swimming next to each other, they would play around at the filter together, they always made sure to share food. Just so much about this is astounding. The fact that the one fish had the wits to recognize that the other was in trouble, the rudimentary quantitative reasoning in sharing the food, and not only the formation of a bond, but the expression of behaviors that are recognized in human relationships like play and altruism.
Like, I know that animals form relationships, I know that fish form relationships by coming together in schools and such. But fish are so alien.
I wrote like 300 words, realized they didn’t make sense, deleted them, wrote this, and now I’m questioning why I explained this.
The alien characteristics of fish like gills, fins, and the unblinking, expressionless eyes and mouth, seem entirely inconsistent with common schemas about sentient creatures. They appear closer to insects, who I would also have characterized as creatures of pure instinct, but now I wouldn’t be surprised to hear that sometimes crickets just chirp because they want to.
Oh wait, Amal and Paris probably don’t have my email. Phillip.mayer0402@gmail.com if you want to send back edits.
I wrote the intro after that last paragraph but threw it back up to the top, as it says.
I also remember being at the pulmonologist and having this book with me. He asked me what it was about, so I started telling him about the study that demonstrated that fish are confused by optical illusions (the point of this was to show that they “think,” in a manner of speaking, with regard to the shape of an object, as opposed to purely reacting to the raw stimuli). Then I was like “wait do you actually want me to talk about fish for this long? Why haven’t you stopped me yet?” and he goes “yeah I just needed to watch you breathe naturally for a moment,” and I was like, “oh.”
This is the point where I go beyond unnecessarily long to bordering on manic and proceed to just ramble about my thoughts and experiences with fish in a context entirely unrelated to the book. If you made it this far, I commend you. Anyone who continues is going to learn A LOT of kind of mundane shit about me.
I do apologize in advance for the following.
Oh wait my chicken is done I’ll be back in a bit.

6/6/2026, 6:38 PM
. . . .

6/6/2026, 8:10 PM
In most of my earliest memories, I’m on the water. My home rests on this canal looking out towards JFK. You’d hear planes humming along every ten or so minutes, but it was rhythmic, so it was easy to tune out.
The ground ends a couple meters past my backdoor, so the rest of my yard is a dock. At the end, a flimsy little ramp runs parallel to the house and down to the water. A significant number of the grays on my mother’s head can be blamed directly on the frequency with which the high tide broke that ramp.
Yet, she’s had it fixed every time.
My father would set up my tiny beach chair right next to his, at the bottom of that ramp with our bucket of live bait between us. Through elementary school, every few weekends in the summer we’d make baloney (yes I’m gonna spell it that way today) sandwiches and grab some ice cold cokes and pull up the bait trap to see if we could waste a few hours on the water.
We call them killies, but I don’t know enough people who fish to say if that’s the norm. If we found six or seven flopping around in our trap, we’d grab the tackle box. They always reminded me of tadpoles, which made me oddly jealous of people who have seen tadpoles in the wild. Not sure why.
After taking a scoop of dubiously colored water from the canal with a bucket, my father would open the trap and plop the killies in.
Small and dinky-looking as it was, my chair still had a holder for my fishing rod, which I’ll get into later, which left my hands free to try and catch the killies between my fingers. I never could. I kept trying to snatch at them and grab tightly, but they were like little slivers of soap that taunt you from the bottom of a tub.
I feel acutely aware of the fact that this review is (1) diverging from the tone of my typical reviews, (2) no longer about the book which I know I mentioned but still, (3) sad sounding[?], (4) probably violating some set of social norms by being what it is.
Now I’m just aware of the number of times I made meta comments. I think at this point I’m just writing to write, and anyone who has made it this far is a victim of questionable amateur art(?) in an odd format on an odd site for it.
But I’m also listening to The Strokes, so.
My dad didn’t typically do it this way, he preferred to just use the net, but I think I’ve seen him catch a killie in his hand every time he tried.
We were at Home Depot one day, and we passed a rack of fishing poles. Uninterested in measuring the bolts that we needed to replace for one of the shelves in the living room, I wandered over and looked for one that looked like it’d be the right size for a six-year-old. Indecisive as ever, I went back to my dad with six fishing rods in disarray across my lap to ask him which one he thought was the best.
After barely a moment, he picked up the black one with yellow and red stripes. In the loopy cursive that all fishing companies like to write their brand name in for whatever reason, near the grip, the pole was stamped “Ugly Stick.”
He explained that the fiberglass would bend instead of snapping.
That fishing rod became to me what some other kid’s favorite stuffed animal was to them. I knew it was ridiculous to have it inside, but anytime we were outside, even if there was no plan to fish, I at least wanted to “check to make sure it was okay.” Sure enough, the fiberglass never rusted, as I had brilliantly worried it would.
My brother Joe would pass the rod back to me after having reeled in another keeper. Andrew was checking on our cousins to make sure they didn’t need help with their bait. In the chair with the cartoonishly fat tires, I focus intently on the vibrations of the spider silk fishing line.
I was almost always frustrated by the catch of the day when we would charter a boat off the coast of South Carolina and cast out a few lines. I always wanted enough for a meal, but usually we were lucky if we got one keeper to share amongst the twenty of us staying at the home we rented that week.
The disappointment was largely overshadowed by the company. Once, we took a small crew (not to sound like this was any sort of legitimate affair by using a word like “crew”) and went out sharking. Sharks and deer are alike in that they’re crepuscular, active at dawn and dusk. Thank GOD for that because it meant we got to head out at sunset instead of before dawn like we typically would. Also thank God for that because being out on a boat lets you watch the sunset over water even though you’re on the East Coast.
That evening we met Nick.
As we pulled out of the bay, the captain let us know to keep our eyes peeled for anything jumping out of the water. With a bit of reverence for things that swim, we all sat quietly and listened for a splash and watched the surface of the waves.
What we were not expecting was for a bottlenose dolphin to hop halfway out of the water ten feet away from the boat. We watched as he did a couple of flips as he kept up with us, we waved back when he waved to us. His name was Nick, so called for the nick in his dorsal fin that he apparently got because he got too excited playing around a boat. Yet, here he was, playing alongside a boat.
I don’t remember if we caught any sharks, but I do remember Nick waiting for us as we headed back to shore.
I think I’m actually starting to taper out now, but I do still have a few other things that I can say, and since we’re past 2,000 words now anyway, might as well just keep going.
We had this speedboat for years. I had kind of a love-hate relationship with it, but my dad absolutely loved it, and my mom absolutely hated it (except when she agreed to come out on the water with us). It was this sleek, bright white machine with yellow accents. It looked out of place next to the dingy, waterlogged wood that made up the dock.
I was on the water by Rockaway with my dad, brothers, and uncles, and we caught this thing that they told me was called a Sea Robin. If you’ve never seen one before, Google it. It has these strange claws that it uses to move along the ocean floor. It looked big enough, so I asked if we were hanging on to eat it later. My Uncle Phil measured it to confirm, but it was big enough that we didn’t have to toss it back. Only thing was that none of them had ever heard of eating a Sea Robbin. We soon found out that battered and fried, it isn’t much different from the Fluke that we caught the same day.

If you made it all the way here, I appreciate you. I also appreciate you if you didn’t. Anyway I’m reading a wizard book now so I’ll shoot for funny again probably with the next review.

[Louise Ramberg · Rating 5 out of 5]

Very cool

[Merrin Foltz · Rating 5 out of 5]

I’m obsessed with this. did you guys know that it can take less than five days for a flounders eye to fully migrate to the other side of the body. that’s crazy!!

[Amy Garry · Rating 4 out of 5]

so for some reason i picked this book up because i thought it would be like meta about fish and if they can feel and how humans feel emotions… anyways it was literally just research findings about how fish can see, smell, hear, etc.

that being said i absolutely adored it and it was fascinating, kind of want to learn about all animals this way. love the way the author presented all the information

[Peyton · Rating 1 out of 5]

It’s great to expand our human centric understanding of intelligence. I may have been the wrong audience for this book because I didn’t enjoy the way the author assumes everyone thinks fish are mindless ignorant beings. He also incorrectly references taxonomic groups and only gives extremely high level descriptions of studies with no synthesis, interpretations, or in text references. Hard to read after Why Fish Don’t Exist or Light Eaters.

[DANI! · Rating 4 out of 5]

this book was fascinating! i really appreciated the authors approach to these teachings, it was all very accessible, yet rich and incredibly well researched and passionate. it is also incredibly well written and relative to the audience which i really enjoyed. i love fish!!!!!!!!

[John Stepper · Rating 5 out of 5]

My dear daughter gave this to me and, well, she clearly gets me. :-)

One each of the 100+ pages I found myself learning something new. Some big things, some small, and all producing an internal (mostly) "Ooh, that's interesting!"

Thanks, Ollie!

[Alissa Lopez · Rating 3 out of 5]

This was my first purely nonfiction book in quite some time. It took me a little while to get into, but once I did, I learned so much about fish. It was truly fascinating to read about their capacities, which far exceed what I thought fish experienced.

[Siena Cohen · Rating 5 out of 5]

Short but effective debunking of myths about fish being brainless...loved that the author used first person here really helped his plea to get readers to be compassionate towards fishiessssss!!!!

[Stephen Baum · Rating 2 out of 5]

Short and fine.

[Abbey Piatt Price · Rating 4 out of 5]

intrigued by the presentation of relevant studies surrounding fish consciousness, enjoyed and agree with the authors views especially regarding fish pain and fish intelligence

[Meow · Rating 5 out of 5]

AWESOME FISH FACTS