A small male wrasse, a restless streak of blue, white and black, is coming to the end of another busy day on the reef, and still a few more fish are waiting for his services. A rabbitfish hovers motionless at the front of a short queue of five or six fish. She has all her fins splayed out and her bucktoothed mouth open as if she’s suffering from a nasty shock. In fact she’s quite relaxed. The wrasse and the rabbitfish know each other well. Today alone they’ve already met at least a hundred times, the larger rabbitfish returning again and again, infested with more parasites.
The clinging bloodsuckers are minute crustaceans called gnathiid isopods, which dart out of the reef and fix themselves to passing fish. Like aquatic ticks they will suck a fish’s blood for about an hour before dropping off. Rather than surrendering their bodily fluids, fish prefer to have these freeloaders unhitched by wrasse, who have become the chief cleaners on the reef. And it’s a task that requires a surprising amount of brainpower.
Hundreds of client fish from dozens of species make regular visits to the cleaning station. The cleaner wrasse has memorised them all, and tailors his services to each one. His livelihood depends on his refined social skills, of cooperation and communication and even his cunning ability to manipulate other fish. A staple diet of parasites, thousands every day, keeps him well fed, but in truth these aren’t the wrasse’s favourite food. He much prefers a nutritious bite of fish skin or the gummy mucus that coats a fish’s body.
One thing he’s after is sunscreen to help block the sun’s harmful ultraviolet rays, which flood shallow, tropical seas. Fish can’t make sunscreen themselves. Most obtain it from microbes in their food. The molecules pass through the fish’s digestive system and are secreted in a protective layer of mucus on the skin; fish drink sunscreen instead of rubbing it directly on their skin, as sunbathing humans do. Another way to get sunscreen is to lick and slurp it off another fish, but the cleaner wrasse knows there are only certain situations when he can get away with that. To maintain his territory on the crowded reef and win the trust of other fish, the cleaner must do a good job of removing parasites, and can’t push his luck. An injured client will swim off and may never come back. And if other fish waiting in line catch sight of the cleaner wrasse cheating and eating mucus instead of parasites, they may well leave and find another cleaning station.
As the wrasse surveys the rabbitfish it’s getting late, and only a small audience is queuing to be cleaned before nightfall. There’s a dusky brown damselfish on her third visit of the day. The wrasse knows he doesn’t have to behave himself in front of this client because she never strays far from her small farm of algae, and there are no other cleaning stations within easy reach. Another waiting client is a surgeonfish, a harmless herbivore he hasn’t seen before, and the wrasse decides to take a chance. He makes a brief show of searching once again across the blue and yellow honeycomb of the rabbitfish’s body, picks off two parasites, then goes for it. The wrasse takes a bite of skin and mucus. The rabbitfish flinches, feeling the scratch of teeth. But just as quickly, the wrasse rubs his fins over her back and belly. It’s an apology of sorts, soothing and calming her until the disgruntled rabbitfish seems to drift into a blissful stupor. Levels of stress hormones in her bloodstream dip a little. It’s probably one reason why she keeps coming back to this cleaning station, even though she knows the wrasse does occasionally cheat.
The mood across the reef then shifts as a new client arrives, a large grouper. Instantly, the wrasse knows this fish is important: she’s big and probably has a good collection of isopods to pick off. More importantly, though, she’s a predator and could quite easily choose to snack on the little fish during the cleaning ritual. Somehow the wrasse senses the grouper hasn’t eaten in a while, and takes extra special care.
It’s time to dance.
The wrasse beats his tail from side to side, then shimmies his fins across the predator’s stocky body, more than ten times his size. The grouper’s gaping mouth yawns open and the wrasse swims right in. He diligently pecks around sharp teeth that are fearful weapons, perfect for impaling small, delicious fish. For now peace is maintained, probably because the wrasse continues to stroke and massage the grouper, pacifying her so that for a while she has no interest in hunting. The two fish, predator and cleaner, strike a deal, and both stick to their side of the bargain. The social bonds between them are strong but not unbreakable. If they met in any other circumstances things would be very different. But here at the cleaning station the wrasse is granted immunity, so long as he restrains himself and eats only parasites.
All the parts of this scene, and many others like it, have played out in front of biologists who have spent countless hours swimming over wild reefs and peering through glass aquarium walls, watching fish interact with one another. These scientists have counted cleaner wrasse picking off hundreds and thousands of parasites; they’ve devised experiments to test how cleaners and clients decide what to do, and to grasp how the fish recognise each other; they’ve watched fish dance and cheat and, yes, apologise. Studies like these aren’t only showing how fish on coral reefs cooperate to stay clean and healthy, they’re also revealing details of complex, clever lives of fish that have long remained overlooked.
A time-worn portrayal of fish sees them as simple-minded creatures, governed by innate reflexes and incapable of thinking for themselves. This perspective is driven by human-centric studies that search among our closest, mammalian relatives for clues as to how and why our own brains evolved. But it’s a blinkered outlook that’s pulled attention away from animals deemed too distant and different from us to be brainy. By looking at fish in new ways and asking the right questions, biologists are increasingly realising that fish think and solve problems with surprising sophistication. Entrenched ideas about water-dwelling vertebrates are shifting, and at the same time fish are bringing into focus a broader, richer view of what it means to be intelligent.
Most animals have some basic level of cognition; they can sense the world around them in various ways, they gather information, process and store it. More advanced cognition – intelligence, if you like – requires learning from the past and using stored knowledge to solve new problems in the future. Instead of hard-wired instructions on how to live, these are steps towards a more flexible, adaptable approach to coping with a changing world.
Intelligence has always been a slippery concept to define, but if we drew up a list of important signs of intelligent life, fish would tick many of them off. Cleaner wrasse, as we’ve seen, communicate with members of the same and other species, and they have excellent long-term memories. They manipulate their clients by massaging them, and have a sense of the other fish’s motivations. Will this client bolt and never come back? Or does it have no option other than to stick around?
The cleaners also manipulate each other. Male and female wrasse often have overlapping territories, and frequently offer their services together. Operating alone, a female will indulge now and then in some mucus-nibbling, but she soon learns not to when a male is around. Whenever she cheats and sends a client off in a huff, the outraged male cleaner delivers a punishment, aggressively chasing and nipping at her. All he gains from her cheating is a black mark against his reputation. To make matters worse, the more nutritious skin and mucus a female eats, the bigger she grows and the greater the chances she’ll change sex, turn into a male and try to take over his territory. As in their relative the Humphead Wrasse, sex is a flexible affair among cleaner wrasse.1 After a few severe scoldings, the female cleaner refrains from cheating, and together the pair provides an honest service.
Beyond the complex social lives of cleaner wrasse, many other fish bear hallmarks of higher thinking, including some abilities that had been thought to be uniquely human. Guppies can count, as can sticklebacks, blind cave fish and various other fish species.2 In lab tests these counting fish show their arithmetic skills by choosing between shoals of different sizes; given a choice, they generally prefer to join the largest shoal. Fish also use tools. Archerfish shoot water bullets, and tusk fish pick up clams and open them by repeatedly smashing the shells against a rock anvil. Atlantic Cod have invented a new way of feeding themselves using makeshift tools. In a Norwegian research lab a few years ago, three cod, in two different tanks, accidentally got their plastic identification tags tangled in a string that released food from an automatic feeder. All three soon figured out this was quicker than using their mouths to pull the string, because that way they had to first spit out the string before eating. These three fish perfected their technique until they could skilfully hook themselves on the feeding string with their tags, give it a sharp tug, then turn around and swallow the food.
Another tick in the box for fish’s higher cognitive abilities is the subtle way they prefer to use one side of their bodies and brains over the other.3 Many individual fish prefer to look at unfamiliar objects or watch for trouble with either their left or right eye. Within a school, some fish prefer to watch their shoal mates through their left eye and accordingly spend more time in the right side of the group, while for others the reverse is true. It’s possible that schools contain an optimum balance of right-lookers and left-lookers, so that collectively they watch each other and stay in formation, while at the same time keeping their outermost eyes on the look-out for predators. This asymmetry in processing and analysing information is thought to underpin our own abilities to multi-task, and it’s involved in various aspects of human behaviour. Many aspects of language, for example, are generally found in the left hemisphere of a human brain.
An important aspect of intelligence is the way in which individuals interact with each other – their social intelligence. A 2012 study of captive Lemon Sharks in the Bahamas showed they learn from each other. Sharks were trained to press a target for a food reward, just as Eugenie Clark did, including the shark she took to the Japanese prince. When individuals were kept with other sharks that already knew what to do, they learned faster than those with no pre-informed tank mates.
Male cichlids from Lake Tanganyika can work out where they fit in a strict social pecking order simply by watching other males fighting. Known as Burton’s Haplos, these are truculent little fish that spend a lot of their time brawling over territories. Pairs of males engage in sharp skirmishes until one of them concedes defeat. The winner is easy to spot: he stands his ground and keeps the bold, black stripes between his eyes, while his opponent fades his stripes and slinks away. Researchers at Stanford University led by Logan Grosenick staged a series of fights between haplos, which they named A to E; E loses every fight; D loses to everyone except E; C only beats D and E, and so on up to A who wins every time. While pairs of fish came to blows, a third fish was allowed to watch from a safe distance in a separate, transparent compartment in the aquarium. Later, after all the fish had been given some time out and their antagonistic colours had gone back to normal, the bystander was given a choice of hanging out with one of the two fighters. Every time he chose the weaker, and hence the safer, fish. This happened even if he’d never seen the two fish actually fight each other. If his choice was between fish B and D, and he’d seen B beat C, and C beat D, he could infer that B should also beat D. He then correctly chose D as the safer male to hang out with.
Working through these logical steps is a form of deductive reasoning that some birds can apparently do, and some primates, including humans once they’re four or five years old. This ability evolved in cichlids, presumably, because working out another male’s rank helps them avoid getting drawn into potentially dangerous fights while maintaining the harmony of the hierarchy.
As well as fighting, many fish cooperate and help themselves by helping each other out. Back on coral reefs, predatory groupers form hunting partnerships with moray eels. When it wants some help, a grouper will hover over a spot in the reef where a moray is resting, and vigorously shimmy its body. This motion catches the eel’s attention; moments later a face appears, and the pair go hunting together. The two predators make a dangerous team. Groupers prowl in open water and prey fish will try to dodge out of reach by darting into the reef. This is where the eel comes in. With its slender body, it can pursue prey through the reef’s narrow cracks and nooks; either it catches the prey, or it chases it back into open water and into the grouper’s waiting jaws.4 A grouper and an eel working together will both get plenty to eat. Now and then the eel loses interest and wanders off. It slips away into the reef’s hidden labyrinth; when it doesn’t re-emerge the grouper tries to rouse its hunter partner, and once again breaks out into a shimmying dance.
At other times, while hunting alone, a grouper might adopt a different tactic if a prey fish escapes into the reef – it simply stops and waits. The grouper isn’t just hoping the prey will emerge; it’s also waiting for help to arrive. For up to half an hour it will hang around until another predator passes by, hopefully a moray eel or a Humphead Wrasse. Then the grouper immediately stands vertically, tail up, and rhythmically shakes its head towards the spot in the reef where the prey dived in. When an eel or a wrasse sees a grouper pointing and shaking like this, it usually wanders over to investigate. A big wrasse can’t enter the reef but its powerful, extendable jaws can crunch the coral and suck out the prey from its hiding place; either that, or they’ll disturb it so that once again the doomed prey leaves the reef and the grouper gets another chance to catch it.
Pointing at things is an important human trait that’s considered to be a key element in language development. These expressive gestures are rare in the rest of the animal kingdom. A chimpanzee will scratch its body to indicate where it wants its companion to groom, and ravens will show each other food, perhaps as a way of forming social bonds. But until scuba-divers spent hours following the hunting, pointing groupers, these gestures were unknown among fish.
To witness and test a fish’s smarts doesn’t require long, involved experiments. If you have pet fish you can test their learning abilities by feeding them at one end of the tank each morning and the opposite end in the evening, and see how long it takes until they gather at the right end ahead of feeding time – a process known as time-place learning. Usually it takes Guppies 14 days to do this (rats take almost a week longer). And the idea that Sheh Hsien, the earliest written record of the Cinderella story, had a lucky Goldfish that recognised her is not so far-fetched. Archerfish have shown that they can learn to distinguish between pictures of different human faces by shooting droplets of water at the one they’ve been taught to associate with food. It’s highly likely, then, that pet fish learn to recognise their owners, too.
Studies of fish cognition are presenting a new view on the evolution of brains and cognition. Fish perform many behaviours previously thought to be exclusive to humans and a few other big-brained primates. This goes against a long-standing theory that primates evolved large brains to deal with the requirements of living in complex social systems. Many fish also have complex social lives and intricate behaviour despite having relatively small brains for their body size.
An alternative and often more interesting view comes not from fixating on the importance of big brains, but from asking how animal minds and cognition are affected by ecology. Brains evolve in just the same ways as other organs and behaviours: they respond and adapt to the world around them, to an animal’s habitats and to other living organisms. Distantly related species may have similar mental skills because they were honed by similar environments. This could be why, for example, cichlids as well as some birds and mammals can make the deductive leap that if A beats B, and B beats C, then A must also beat C. This ability solves comparable challenges of gauging social rank. Equally, we may see closely related species with different levels of cognition because they’ve adapted to live in different environments. It’s a Darwinian perspective of cognition that subscribes to the obvious truth that brains don’t evolve in isolation; they don’t float in jars lined up on shelves – they’re lodged inside animals that swim, crawl and fly, hunt or graze, climb mountains or scramble through forests.
In adopting this ecological approach, the 30,000 or so species of fish become a powerful experiment in brains and thinking. Fish show how flexible brains and cognition can be, and how ecology matters.
Take, for example, the gobies living on rocky shores that memorise the world around them so they can make a quick getaway when they need to. At high tide these blotchy little fish swim around forming a mental map of local landmarks, learning the shapes of rocks and figuring out where pools will form as the water ebbs away. Then when the tide is out, if a predator looms near, the goby leaps in precisely the right direction and for the correct distance to dive straight into a nearby pool, even if it can’t see where that is. When scientists remove these gobies from their homes, the fish can still remember the pool layout several weeks later. Pool-dwelling gobies are much better at learning to navigate and figuring out where they are than other gobies that live on open, flat sand. Pit these two goby species against one another in a task to learn a route through a maze, with a reward of food at the end, and the pool goby is usually the winner.
On the face of it, the sand goby looks to be the one of the pair with the lesser brain; indeed, a pool goby has a larger telencephalon, the brain region responsible for spatial learning. But if we ponder why this is, the answer comes from the sand goby’s everyday surroundings. Living in a flat, featureless realm, it isn’t accustomed to encountering local landmarks, so this kind of navigation simply isn’t relevant; it just swims up and down the shore as the tide goes in and out. In other studies, fish grow up to be better navigators when they’re reared among seaweeds and rocks rather than in plain, empty tanks; the relevant parts of their brains grow bigger, with more connections between neurons. Throughout life, the shifting, changing environment leaves its mark on what goes on inside a fish’s mind.
Bit by bit, studies like these are reframing the mainstream scientific view of fish brainpower and showing that these animals are far smarter and have much more sophisticated lives than they’ve long been given credit for. This raises a bigger question: are fish sentient and conscious beings?
Scientists and philosophers have historically struggled to define these concepts. Sentience involves an animal’s ability to experience and feel sensations, including pleasure and pain. Consciousness is even harder to explain. As The Blackwell Companion to Consciousness puts it, ‘anything that we are aware of at a given moment forms part of our consciousness, making conscious experience at once the most familiar and most mysterious aspect of our lives.’ How, then, does this experience apply to other animals? Very broadly speaking, we can think of conscious animals as having a sense of self, and some understanding of their place in the world.
Consciousness is generally thought to be a property that emerges from higher intelligence and sentience. A key criteria for consciousness, and one we have some hope of testing for, is self-awareness – the ability to recognise and think of oneself as an individual.
For several decades, a classic way of assessing self-awareness has been the mirror test. The method involves giving an animal a mirror and watching what happens next. Many animals will initially respond to their reflection as if it were another animal; in this way experimental fish often launch a territorial attack on their reflection, assuming it’s an intruder. Some animals may then inspect the mirror and look behind it, and repeatedly look into it as they begin to learn that they’re looking at themselves. Chimpanzees have been seen to pick their teeth and dolphins blow bubbles in front of the mirror.
A final step in the test is for the researcher to apply a sticky coloured dot to a part of the animal’s body that it can’t normally see, often the forehead. Around 75 per cent of chimpanzees tested this way will look in the mirror and reach up with a hand to touch the dot. Humans start doing this aged 18 months. Primatologists interpret this as self-awareness. The chimp and young human know they’re looking at themselves in the mirror; they know what they should look like and the dot on their head is something unexpected, so they poke it to see what’s going on.
Only a few other species have passed the mirror test. Eurasian Magpies have looked in a mirror and scratched with their feet at a coloured dot stuck to their throat, but have ignored less conspicuous black dots on their black feathers. At the Bronx Zoo in 2006, a ‘2.5m- tall elephant-resistant mirror’, as the study authors put it, was presented to three Asian Elephants. All three spent time in front of the mirror apparently checking out their reflections. When invisible sham marks were painted on the side of their heads all the elephants ignored them – understandably so, because there was nothing out of the ordinary for them to see. Two of the elephants also ignored a coloured mark, but one of them, a female called Happy, repeatedly reached her trunk to apparently investigate the white cross painted above her eye.
Bottlenose Dolphins and Orcas, it’s often claimed, have passed the mirror test by checking out their reflections for prolonged periods and gazing at coloured dots painted on their bodies (they don’t have hands, beaks or trunks that they can touch other parts of their body with, so that part of the test doesn’t apply). In 2016, Csilla Ari and Dominic D’Agostino from the University of South Florida tried this on fish for the first time. They lowered a giant mirror over the side of an aquarium tank in the Bahamas, and filmed the response of two Giant Oceanic Manta Rays (with no coloured dots applied). The mantas spent a long time circling in front of the mirror, repeatedly unfurling their two cephalic lobes, the horns that channel plankton into their mouths and – like dolphins – blowing bubbles.5
Ari and D’Agostino cautiously interpreted this as a process known as contingency checking; in a similar way, you might wave a hand to check it’s your distant reflection in a window. If that is what mantas are doing, then it supports the idea that they recognise themselves in the mirror and have a sense of who they are. Other researchers, though, have been highly critical of these findings and suggest the mantas were simply being social and thought they were hanging out with other mantas. The same criticisms could equally be levelled at many other mirror tests, including on marine mammals. But those studies prove to be far less controversial, perhaps because they fulfil the expectation that mammals, especially cetaceans, are intelligent, rather than challenge the deep-set belief that fish are not.
A growing appreciation of the thoughtful lives of everything from Guppies and Goldfish to mantas and cod plays into the most controversial idea surrounding fish and fish cognition: the long-standing debate over whether or not fish feel pain.
The default position for a long time has been that fish neither suffer nor feel pain. Most advocates of this position say that until and unless evidence is found to prove fish do feel pain, we should assume they don’t. However, studies are beginning to provide just the kind of data to undermine this viewpoint.
In 2003, researchers from the Roslin Institute at Edinburgh University found that fish are hardwired to detect pain. The team, led by Lynne Sneddon, located in Rainbow Trout a type of nerve cells that specifically senses various noxious stimuli, including high temperatures, acid and bee venom. These cells are very similar to the sensory nerves that detect pain in mammals. Since that discovery, there’s no longer been any doubt that fish have neurons dedicated to responding to stimuli that can harm them and which are associated with causing pain (albeit only in teleosts so far; equivalent receptors for noxious stimuli have not yet been found in elasmobranchs). The only remaining question is how fish perceive this sensory input.
Clues come from watching fish when they’re exposed to stressful and potentially harmful situations. Numerous behavioural studies suggest that fish want such scenarios to stop – one of the hallmarks of pain. When Lynne Sneddon’s team injected weak acid or bee venom into the lips of Rainbow Trout, the fish lay on the bottom of the aquarium tank and rocked from side to side, or they rubbed their lips against the side of the tank; they didn’t respond like this when they were injected with harmless blanks, so it wasn’t the injection itself that was upsetting them. Moreover, the trout stopped behaving this way as soon they were given a dose of morphine – one of the most potent painkillers in humans.
Pain may also dominate a fish’s attention and distract it from performing other tasks (chronic or intense pain can do the same thing in humans). In 2009, Paul Ashley at the University of Liverpool led a team that tested the anti-predator responses of Rainbow Trout with and without exposure to potentially painful stimuli. When captive trout sense alarm chemicals released by damaged fish tissues, they normally swim around the aquarium tank looking for somewhere to hide.6 But trout with acid-injected lips didn’t try to hide when the signal of danger rippled through their tank – they ignored the alarm chemicals and seemed to be distracted by the pain.
None of this will come as any surprise to the many biologists who consider that the detection of potentially painful stimuli and pain perception evolved hand in hand, because together these entwined processes boost an animal’s chances of survival. By learning to associate dangerous situations with painful feelings, and then trying to avoid that pain, animals keep themselves out of trouble. A key driver for the formation of memories is likely to be the emotional response to pain. It’s widely thought that this paired ability, to detect dangerous events and to mount an unpleasant, emotional response to them, is an ancient survival tactic that evolved early on the vertebrate lineage.
Further studies have also indicated that fish can suffer the effects of stress. Zebrafish seem to undergo emotional fevers, a rise in body temperature caused purely by stress or anxiety, something else that had previously been thought to happen only in humans (stress in the run-up to exams can give students the same physiological response as that caused by an infection). When confined to a small net, Zebrafish’s temperature increased by between 2 and 4ºC (3.5–7ºF). What’s more, farmed salmon routinely display symptoms of depression. Known as ‘drop outs’ in the industry, up to a quarter of the stock will have stunted growth, with these animals hanging out near the water surface where they are easy to catch. A 2016 study measured high levels of cortisol in the dejected salmon, a hormone that’s commonly released in response to stress. Similar overactivity of the system that regulates cortisol levels, as well as those of the hormone serotonin, has been linked with chronic stress and depression-like states in other animals, including humans.
The case against fish feeling pain takes the stance that observed behaviours could simply be automatic reflexes that don’t involve any emotional suffering. When you touch a scalding surface you feel a jolt and pull your hand away a beat before the pain kicks in; maybe fish don’t get to that point of feeling pain and simply know when to withdraw themselves from danger.
Central to this argument is the contention that fish don’t have a region in their brains that in humans seems to be involved in pain perception. The cerebral cortex is the outermost part of a mammal’s brain. In humans, this grey matter is roughly 4mm (0.16in) thick and made up of many characteristic layers of neurons and their wiry extensions. It’s folded into deep grooves and ridges, and is involved in crucial aspects of our lives, including sight, hearing, learning, feelings of suffering and stress and the perception of pain. Look inside a fish’s skull and you won’t find a large, mammalian-like cortex, but rather a string of small, globular beads.
No cortex: no pain. So the anti fish-pain argument runs. The premise is that fish lack the kind of complex neural architecture that allows humans to process streams of information, to extract unpleasant sensations and to know that we’re hurting. The only way for other animals to feel pain is the human way. This is the stance taken in 2016 by Brian Key, a neuroscientist and prominent fish-pain sceptic from the University of Queensland in his article in the journal Animal Sentience entitled Why fish do not feel pain. Notable academics from a range of scientific disciplines published 42 written responses to Key’s piece: five supported his view; two gave a neutral view that more studies were needed before making any substantive claims either way; the rest, 35, were highly critical of Key’s science, reasoning and assumptions.
Among critics, neuroscientists pointed out that there’s no consensus yet over just how important the cortex is for pain perception in humans, let alone what the implications are for a lack of cortex in other animals. Focusing solely on the cortex also ignores the distinct possibility that other regions of fish brains could be involved in pain perception. The same goes for birds and various other animals that don’t have a highly developed cortex, but are assumed to be sentient.
Carl Safina, Professor of Nature and Humanity at Stony Brook University in New York, uses stingray venom as testimony to fish feeling pain, in his response to Key’s claims. Safina points out that stingrays, along with many other venomous species, evolved their venoms as defence against predators, including marine mammals and fish. And as we’ve already seen, many venomous fish evolved bright colours as a warning to predators to leave them alone or risk getting stung. For these warning colours to be effective they must be backed up by actual noxious defence (except for the mimics that skilfully imitate venomous species). Key asserts that predators need not feel that painful sting to learn to avoid it, a viewpoint that Safina rejects. ‘It is nearly inconceivable that a predator would avoid the threat of a nasty sensation that it could not feel,’ he writes. ‘It seems logically inescapable that pain is what makes all this work.’ Some animals, he points out, do seem to be immune to some of nature’s stings. He describes watching sea turtles munching Lion’s Mane Jellyfish and showing no signs of being stung; meanwhile, he recounts seeing a Blue Shark taking a mouthful of the same jellyfish species, then vigorously shaking its head and spitting the jellyfish out. ‘The shark showed behavior consistent with pain,’ Safina writes, ‘the turtles do not.’
There’s a lot riding on the issues of fish sentience and consciousness. Arguments are generally rooted in the scientific understanding of their pain perception and suffering – or lack thereof – but the implications resonate far beyond the boundaries of science.
This is part of a broader matter of how much of our attention, empathy and even fondness we bestow on other members of the living world. The way we treat animals and interact with them is swayed by how we think of them as sentient, intelligent beings, by the perceived simplicity or complexity of their lives. On the whole, the animals we care for most are the ones considered to be beautiful or that look back at us with thoughtful, knowing eyes: those most like us.
Since the early 19th century there’s been a variety of legislation put in place to protect certain animals against pain and suffering. In 1822 the Cruel Treatment of Cattle Act was passed by the UK Parliament, banning the improper treatment of cows as well as sheep; the 1835 Cruelty to Animals Act included dogs and goats, and outlawed bear-baiting and cockfighting. Public opinion in western societies has gradually shifted towards supporting animal rights and the need to protect and look after animals in our care, from the treatment of pets and zoo animals to the design and regulation of abattoirs and the production of free-range eggs and meat.
But not all animals fall within the same legal and moral boundaries. Historically, the ethical treatment of fish has lagged far behind that of other vertebrates. Nevertheless, the science of fish cognition and sentience is catching up. Studies are chipping away at this assumption that we can get away with treating fish as lesser beings. As we’ve seen, scientists are devising methods to measure fish’s abilities and compare them to other, more familiar animals. It’s becoming clear that fish live complex, intelligent and nuanced lives, and evidence is stacking up that fish can suffer, that they get scared and they can feel pain.
Given what we now know about the lives of fish, where does that place them on our scale of empathy and ethics? How should we treat fish?
Answers to those questions are still unfolding. We’re only just beginning to grapple with the potentially profound implications that come with the knowledge that fish are in fact brainy creatures. The issues are made more complicated by those emotive terms that can be difficult to grasp – sentience and consciousness, pain and suffering. Moreover, fish still face the same, age-old problems of being so different to us land-dwelling, air-breathing humans, and they live in a realm few people see and experience.
In different countries, different lines are being drawn with respect to legislation over the treatment of fish. In the UK, the Animals (Scientific Procedures) Act 1986 regulates the use of animals in scientific studies, and requires researchers to obtain a licence in order to experiment on a list of protected animals, and follow a strict Code of Practice on how to rear and handle them. The list encompasses all vertebrates plus cephalopods (once they’ve hatched), due to the higher cognitive powers of octopuses and their relatives. Fish are included, although specifically only once they can feed themselves independently. By contrast, all fish are excluded from equivalent legislation protecting animals in the US under the Animal Welfare Act.
There’s also UK legislation protecting fish kept as pets. In 2017, a British man was convicted of cruelty to animals after he posted a video on Facebook of himself apparently swallowing a live goldfish for a bet. Officers from the Royal Society for the Prevention of Cruelty to Animals (RSPCA) saw the clip and launched an investigation. The man, along with the woman who filmed him, claimed they thought the fish was already dead. Their pleas were rejected in court and the pair were jailed for 18 weeks, ordered to do 200 hours’ community service and banned from keeping fish for five years. According to the BBC news website, the convicted man said, ‘I didn’t think eating a fish could cause this much trouble.’
The German Welfare Act states that ‘no-one may cause an animal pain, suffering or harm without good reason.’ And that includes fish. Under this act, it’s argued that for recreational fishers to catch and then release fish causes suffering without any ‘good reason’ and so this practice is illegal. All fish caught must be landed and taken home to eat (except if anglers accidentally catch undersize fish or a particular protected species). Similar legislation bans catch-and-release fishing in Switzerland. Other countries take an opposing view and encourage this approach as a conservation tool, to prevent overfishing.
Clearly there’s a mixed picture, and no one way in which all fish are treated in all places. And certainly, the science of fish brains and intelligence is taking time to trickle more widely into public awareness. Resistance to a shift in attitude is fuelled, in part, by the immense vested interest in fishing industries. If fish were to be treated the same as other vertebrates, and equivalent welfare legislation introduced to the fishing and aquaculture industries as for farming, it would require radical changes to the ways wild fish are caught and to the methods used to rear them in captivity. But there’s simply too much material investment, too many jobs and too much money at stake for this stance to easily take hold.
It’s unrealistic, then, to expect a wholesale change in the treatment of fish any time soon. Perhaps, though, we can hope for a shift of public opinion in favour of fish, one that allows them greater respect and appreciation. Already we’ve moved on from myths of a Goldfish’s seven-second memory and thrown out many defunct beliefs about the fish’s dull-witted lives. It turns out they do have all those fundamental abilities it was variously assumed they lack: they can think, learn and remember, they can see colours, they can hear and sing. And fish have countless other curious and unexpected talents: they cast electric beams around them to hunt and find their way; they send out covert messages by manipulating light and colour; they sculpt giant shapes in the sand; and they use inbuilt magnetic compasses to swim across the oceans and back. But still there’s a long way to go to redirect the common view that fish are inferior creatures, that they’re wholly different from dogs, horses, cats, birds and all the animals that have been regarded as loyal parts of human life for thousands of years.
There are many ways we can redress this balance and close the conceptual gap between fish and other animals. We can pay attention to the fish that we eat, and keep as pets, and ask questions about where they came from and how they were caught or farmed. We can advocate for continued research into the lives of fish, to learn yet more of their biology – and pay good attention to the results of those studies – and we can learn more about how human activities affect them as individuals, populations and species. And you can cultivate your own, personal connections, and get to know these animals better by going into their aquatic world and giving yourself over to the joys of watching fish.
Notes
1 There are five known species of cleaner wrasse in the Labroides genus, living in the Indo-Pacific region. In the Caribbean, neon gobies perform a similar role.
2 Non-fish, non-human animals that can count include chimps, elephants, dogs, dolphins, pigeons, beetles and bees.
3 This is known as cerebral lateralisation, which occurs in many different animals and varies between individuals, populations and species.
4 Groupers sometimes go hunting with octopuses, which can also slip into a reef.
5 Mantas don’t breath air, but it can accumulate in their gills when they’re filter-feeding, which is how they’re able to blow bubbles.
6 Known as schreckstoff, these alarm chemicals are common in the otophysan fish with bony connections between their swim bladders and inner ears.