Six Fish That Are Smarter Than We Give Them Credit For

By Yao-Hua Law | March 3, 2015 11:34 am


Name a smart animal. Perhaps dogs, or dolphins, or chimpanzees came to mind. But why not goldfish, salmon, or moray eels?

Most people don’t associate intelligence with fishes. Blame it on the misconception that evolution is linear, with fishes sunk at the primitive end and primates raised near the top. Increasingly, though, scientists are appreciating the full spectrum of fish behaviors in their natural environments, thanks to advances in technology such as underwater ROVs and better recording equipment.

“In the past ten years, there has been a sea change in how scientists view fish intelligence,” says Culum Brown, who studies fish behavior at Macquarie University. Brown notes that some scientists would still deny that fishes possess basic cognitive skills.

Scientists have found that not only can fishes perceive their environments using complex senses, but that they can also coordinate hunts, use tools, and remember and learn – sometimes better than rats and toddlers.


Yellow bullhead.

I See – and Smell and Hear – You

We humans see in three bands of the light spectrum – blue, green and red. That makes our vision trichromatic. Most fish, however, are tetrachromats, able to see in the same three colors and also ultraviolet. Many fishes see objects as clearly as we do.

What’s more, fish can smell and taste impressively well. Chemicals permeate easily in water, and fishes have equipped their gills, fins and mouths with lots of receptors. For example, the yellow bullhead has 175,000 taste buds across its body; our tongue has only 10,000.

And though we don’t often think of it, fish are incredible auditory creatures. We now know about a thousand fish species that make and use sounds to facilitate mating, feeding and group dispersal. Some, like the meagre (Argyrosomus regius), a fish that weighs up to 110 pounds, make such loud grunts during mating that they expose their location to eavesdropping fishermen.


Rainbowfish. By Eileen Kortright (Roan Art)

Making Connections

A basic sign of intelligence is so-called associative learning – basically, what Pavlov demonstrated with his dogs.

Fish can also accomplish this feat. For instance, pet fishes often demonstrate time-place learning: they remember when and at which ends of the aquarium their feeding occurs.

And lab experiments have found that in some cases fish are better at this than mammals. Galaxias, a common freshwater fish, accomplish time-place learning in 14 days while rats need 19. In another example of associative learning, wild rainbowfish learn to link food with lights-on in 14 trials, whereas rats need 40 trials to associate food with a sound.

Goby fish. Image by  Khoroshunova Olga/ Shutterstock

Goby fish. Image by Khoroshunova Olga/ Shutterstock

Learning the Layout

Fishes are better navigators than most human toddlers. After encountering an object, many fishes associate the object with the location’s basic geometry (e.g., always in the oblong corner of a chamber). Fishes can also combine salient features of the environment, say a patch of grass next to the object, with geometric information to augment memory. In contrast, children learn to use featural cues only after five years old.

Gobies that live in rock-pools provide a classic demonstration of such spatial learning. Researchers simulated high and low tides in the lab and let gobies explore neighboring pools during high tide. During low tide, if these gobies were startled (i.e., the researchers poked them with a stick) they overwhelmingly jumped into adjacent pools. Spatial learning in this instance saved them from falling onto a sandbank.

Atlantic salmon. Credit J. Helgason/ Shutterstock

Atlantic salmon. Credit J. Helgason/ Shutterstock

Fish Schooling

That salmon on your plate may very well have been a mentor in his past life.

In captivity, young Atlantic salmon often wait a few minutes before they strike at a new food item. But after being in a tank with experienced salmon, who strike immediately, the youngsters become far bolder than if they are housed with other naïve salmon.

Scientists think that imitation allows younger fishes to acquire other kinds of crucial knowledge, for instance migration routes and foraging locations, from older fishes, and helps retain tradition in fish schools.

Grouper. Credit Sergey Dubrov/ Shutterstock

Grouper. Credit Sergey Dubrov/ Shutterstock

Trust and Teamwork

Cooperation requires some complex brainpower. In fact some scientists speculate it was the force that sparked the human brain to get so big.

And it turns out, with their tiny brains, fish are capable of pretty advanced alliances too. Groupers and moray eels are the only known example of two different species working together to hunt.

It works like this: The eel snakes into the crevices of the reef, flushing out reef fishes into the open waters, while the grouper patrols outside, scaring fishes into the reefs. Whichever way the fishes escape, they are likely to swim in the direction of a gaping mouth – either of a grouper or eel. Both groupers and eels catch more prey hunting together than alone.

Black-spotted tuskfish. Image by Wild Singapore via Flickr

Black-spotted tuskfish. Image by Wild Singapore via Flickr

Using Tools

Tool use was once heralded as the cognitive leap that only humans had made. Then, beginning with chimpanzees, scientists discovered tool use across a diverse range of animals: crows, vultures, otters, and octopi. What’s less known is that fishes, too, use tools.

The black-spotted tuskfish has got its feeding routine down to a science. It feeds on animals that protect their soft bodies in hard shells: crustaceans, snails and clams. Clamping a clam in its mouth, a tuskfish whams it into the rock – left, right, left, right – until the clam shell breaks. In a similar approach, some species of wrasse crush urchins against corals to break their spines and feed on their soft insides.


So, able to learn, form social alliances and use tools, fishes – including many that end up on our plates – are undeniably intelligent creatures. How would you now view your pet fish or your grilled salmon? You decide.


Top image: Fish by Rich Carey/ Shutterstock; Coral by abeadev/ Shutterstock

CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: animals, fish
  • MaryFinelli

    All fish are much smarter than most people probably realize. They’re also sentient -able to suffer fear and pain- as science has shown. Fish deserve to be respected and protected, not exploited and consumed.

    Please don’t cause them – or any other animals – needless harm. All of the nutrients we need to thrive are available from plant sources. They’re better for us, for the other animals, and for the environment. If you eat seafood, please opt exclusively for vegan seafood. Recipes, products, and more information about fish is at Fish Feel.

    • GuestWhom

      Unfortunately everthing that lives must die at some point. The world needs microbes, insects, plants, herbivores, carnivores, omnivores, etc to keep the system going. If you are a vegetarian you still kill many things with brains that can feel pain…every time you drive your car many insects die, I farming practices, etc. It is impossible to live a human life and not cause the death of something.

      • MaryFinelli

        That is true but we can act to cause the least suffering and death. We can thrive on a vegan diet; fewer plants and animals are killed by doing so, and there is less environmental destruction. It can also be healthier for us.

        • Zak77

          Oh my God you’re like a broken record… maybe instead of worrying about others worry about your own choices.

          • MaryFinelli

            And yet you remain oblivious. I’m concerned about the choices we each make and their collective impact. You should be, too. Ignorance isn’t bliss.

          • Zak77

            Oh I’m quite aware. Most of my girlfriends were huge animal rights advocates and strictly vegan. But you know what they didn’t do? Go on and on and on about telling others what they should do. I ate meat, fished, hunted ( fun fact the deer where I live breed so damn much they starve to death. It’s one of the few instances hunting isn’t inhumane. Especially if used with an arrow or crossbow. Less trauma on the animal) and we accepted our differences. You’re practically a god damn spam bot for veganism from what I gathered on your page. Jesus. If I heard you talk like that at a bar I’d probably pour a beer over your head

          • MaryFinelli

            Well if they realized you were abusing animals they should have told you to stop it. Of course, given the aggressive way you say you’d probably treat me they probably were afraid of you. What’s puzzling is why they would want to be with anyone like you in the first place.

          • Kaal Singh

            Zak77, The reason you do not understand Veganism and have no care for animals is because you have been taught and conditioned by a violent society to believe it is morally acceptable to exploit, oppress, torture and murder innocent, defenseless, vulnerable, less intelligent, weak and different-looking beings. As long as you get benefit, it is fine. We have been taught to love some and eat others, that animals are inanimate objects devoid of life, pain, intelligence and emotions. That we should worship our egos – that superiority means exploiting others that we believe are less superior.

    • dagobarbz

      I don’t practice catch and release. To me, that is just torturing animals for pleasure.

      I practice fillet and release. Mmmm…fillets…

    • Michael Thomas

      Dumb hippie.

      • MaryFinelli

        An ad hominem insult about someone you know nothing about is the best response you could manage? Pathetic.

        Fish are smart, can’t say the same about all people.

  • Mark Caponigro

    This is a fascinating, well-written, and ethically important article, which can begin to help us understand and appreciate bony fishes as sentient creatures meriting high moral regard. Thanks very much, Yao-Hua Law!

    And the photographs are gorgeous too! I especially like the Atlantic salmon, and the grouper.

    No taxon of animals suffers so much, by number of fatalities, as the bony fishes, with sardines to their sorrow in the lead. (And the much more distantly related cartilaginous fishes don’t have it so good either.) Any contribution to public discourse that raises our esteem of them, such as this article, is a praiseworthy step in the direction of true moral progress.

    • psybermancer

      Agreed. This is one of the only articles that I have read in full for weeks. Very well written and engaging.

      • Yao-Hua Law

        Thank you very much, Mark and Psybermancer!

  • Mike Richardson

    Great, now I can feel as much guilt eating sushi as I do eating bacon or a sirloin steak. Not enough to quit eating them quite yet, though. But it is food for thought, about food no less.

    • GuestWhom

      Actually you should probably feel guiltier for eating fish on some levels since more fish are wasted by large fishing vessels than many other domestic animal like pigs and cows. I think eating chicken would probably be the least guilty meat decision since raising chickens is less taxing on the environment than most other domestic animals and are more sustainable than fish in a lot of ways.

      • MaryFinelli

        Relatively little meat is obtained from fish and birds, and GuestWhom is right about the many fish (and other animals) who are incidentally killed by fishing. I hope you will instead opt for a vegan diet, which is least harmful to animals and the environment and can be most healthful for us.

      • Mike Richardson

        Yeah, and those Chik-Fil-A cows make a pretty good argument about eating more chicken. And, as I was eating my sushi this evening, I was appropriately concerned that there wasn’t too much by-catch. Still, it’s a good source of protein, and to be honest, pretty delicious compared to standard vegan fare. Plus, I console myself with images of orcas going after baleen whales, and sharks eating other fish, and realize that nature’s actually a lot crueler than most people. I’m all for sustainable fishing, but I’m not going to give myself an ulcer worrying over whether I’m eating a fish that in all probability, will be eaten by something at some point. Not that we should be needlessly cruel, but according to a lot of evolutionary biologists, it was eating meat that gave us the extra boost in brainpower to cement our place at the top of the food chain. Well, I’m doing my best to reduce the amount of meat I eat, though I think eggs and milk should be pretty morally acceptable even to vegetarians. And I just don’t think I can give up chocolate milk.

        • facefault

          Well, eating highly calorie-dense food in general. We likely wouldn’t have become human without hunting, but developing tools to get fruit, tubers, and nuts was also important. (And modern tropical hunter-gatherers get ~75% of their calories from plant foods, indicating that our ancestors most likely did as well).

  • dagobarbz

    Every generation shares tales of legendary fish too wily for anglers’ tricks.
    Catfish, bass, big trout; they have names and tales are told of them in taverns and bait shops. There are legendary 20 lb. bass in a couple San Diego reservoirs. They’ve been seen, even hooked, but so far, not landed. No mean feat when a 20 lb bass is worth a million bucks to the lucky angler in endorsements.

    “I always troll with my Rapala countdown. It works? For me.”

  • Ghengis_John

    They don’t really “form alliances” if their behaviors just happen to help each other out. Word meaning is important and you’re trying to make it sound like they confer with one another and form a plan of attack. If a person gets trapped between a brush fire and a canyon wall that doesn’t mean that the wall and the fire “formed an alliance”.

    The whole article is hard to take seriously because this pattern of hyperbole is used again and again. It’s one long exercise in anthropomorphism and grasping at straws.

  • Sara3346.

    Indeed it would be worth an update perhaps.

  • Joanna Forbes

    How about Sheepshead? They are very tricky to deal with at times.

    • Adri Willes

      probably depends on the individual,there was a sheepshead that we gave a chicken leg to when i was little and instead of eating the ripped off pieces it swallowed the whole leg and choked….not too smart…

      • Joanna Forbes

        That is seriously not smart on your end. Way to kill a fish. 😛 They deal with enough of our human waste. Smart fish or not, fish will eat most things they think they can swallow.

        • Adri Willes

          I was like 5 or 6 and my dad was drunk, how was I supposed to know,I thought I was just being nice and feeding a cool fish XD .And it did not die,it eventually got it back out after like 10 seconds


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