Owen Walsh
Now that we know fish have thoughts, emotions, and pain receptors, it’s time to let them off the hook.
Despite the common mischaracterization in popular culture that fishes’ brains are not complex enough to “feel” things like emotions or pain, prevailing scientific evidence leaves little room for doubt that fish are capable of suffering, not only physically, but mentally too.
Society has long upheld the myth that fish, and other non-mammalian creatures like chickens and insects, lack intelligence or even sentience. Because of this assumption, fish have historically not gotten the respect they deserve. And just like chickens, pigs, cows and other animals raised for food, fish within the factory farming industry have their rights as feeling, emotional beings violated from the time they're hatched until the moment they're killed.
Do fish have feelings?
Yes, fish most certainly have feelings. Scientists have made great strides over the past couple decades in recognizing the sentience of fish. Unfortunately, many governments around the world, including the United States and United Kingdom, have lagged behind the scientific community by not establishing animal rights for fish.
The most basic animal rights do not apply to fish. The U.S. Humane Slaughter Act was signed into law in the 1950s, and requires slaughterhouses to ensure that livestock animals such as cattle and swine are made quickly and effectively unconscious (known as "stunning") before they're killed. The act leaves out some of the most commonly slaughtered animals, however, including fish.
Fish are provided so little protection, US law actually still regards them as property—not as the sentient animals they are.
How do we know fish have feelings?
We know fish have feelings thanks to science! Scientists have employed many different studies that reveal the emotional lives of fish. Some experiments observe the behavior of fish when placed into differing environments, while others actually measure a fish's physiological reactions, like changes in hormone levels, to different stimuli. In "Fish intelligence, sentience and ethics," researcher Culum Brown provides an overview of various experiments on fish sentience and concludes:
[Fish] are sentient and the evidence that they are capably of feeling pain in a manner similar to humans is gradually mounting. I submit that there are compelling reasons to include fish in our ''moral circle'' and afford them the protection they deserve.
A particularly interesting experiment from 2011 found that fish achieve stress relief through soothing physical contact. Researchers studied surgeonfish—commonly known as tangs—who in their natural habitat of coral reefs will frequently visit a smaller fish known as cleaner wrasses. The two species share a mutually beneficial relationship in which the cleaner wrasses eat parasites and dead skin off of the surgeonfish.
In the study, scientists exposed a set of surgeonfish to models of cleaner wrasses which moved mechanically, while another set of surgeonfish were exposed to non-moving wrasse models. The surgeonfish who were gently caressed and stimulated by the mechanical models had significantly lower cortisol levels—the hormone associated with stress—than the surgeonfish whose models were stationary.
Studies like these show us that fish are comforted and relaxed through physical contact, akin to the way massage therapy can help humans' mental health.
What emotions do fish experience?
On the surface, fish and humans appear to share very little, if anything, in common. But by looking beyond the superficial differences, scientists have discovered that fish exhibit emotions analogous to the ones we experience.
Here's an easy one to understand: Fish like to have fun. Fish that live in aquariums and tanks will cruise through bubble streams like they're riding roller coasters, and mobula rays will leap out of the water several feet into the air for no apparent purpose besides sheer enjoyment, according to biologist Jonathan Balcombe.
Fish can also be particular about choosing a mate, and when separated from their chosen partner, they become more pessimistic. A study in 2019 found this out by presenting a female fish with two potential mates and allowing her to to pick a favorite. Some females were paired up with the males they chose, while other unlucky bachelorettes got stuck with the males they had rejected. For the remainder of the experiment, the fish who didn't get their desired mate exhibited less optimism in general. In other words, the disappointing experience left the fish with a "glass-half-empty" attitude.
There's also evidence that fish are capable of feeling fear. Researchers in Canada tested this out by exposing rainbow trout to frightening stimuli, plunging a net into the trout's tank whenever a particular light was turned on. The trout learned to associate this light with the frightening net, and would escape to safety when the light came on, even before the net was plunged into the water. This fear stayed with the trout for at least a full week, showing the "learned avoidance response" on the first occasion they were tested after seven days without testing.
Do fish experience pain?
Yes, fish experience both physical and emotional pain. Scientists say that it's likely a different type than what humans experience, but it's pain nonetheless. Fish have nerve cell endings called nociceptors, which alert their bodies to potential harm such as high temperatures, intense pressure, and harmful chemicals. They produce the same natural painkillers, called opioids, as mammals do. And similarly to mammals, birds, and other land-dwelling vertebrates, fish experience a rush of electrical currents that run through their brains when injured.
Unfortunately, many of the methods used in the commercial fishing industry subject fish to both types of suffering, physical and emotional. A 2019 study found that trawl-caught cod and haddock were found to be conscious even two hours after they had been pulled out of the water. Instead of being stunned in a quick and humane way, these fish were forced to suffocate slowly and painfully.
Sadly for many fish, the suffering is twofold, because the method in which they've been caught has injured them in some way.
Do fish feel pain when they are hooked?
There's almost no doubt that fish feel pain when they are hooked. Fish have a high concentration of pain receptors inside and around their mouths and lips, where they're most typically pierced by a hook. One study found that when rainbow trout were exposed to a painful stimulus, their behavior and physiology changed for a prolonged period—suggesting that the fish were feeling the effects of pain. A similar study found that trout who were simultaneously injected with a painful substance and morphine—a drug that dulls pain—behaved as they normally would, as opposed to the fish who were not given morphine. This shows that being exposed to pain alters their mental state, similarly to what pain does to humans and other mammals.
Do fish have thoughts?
In humans, a thought is our brains' representation of something we've perceived with our senses, felt with our emotions, or formed as an action plan. Many thoughts are "stored" in our brains as memories. Scientific experiments have found that fish are capable of storing important information about their surroundings in their memories, and acting accordingly.
Salmon are able to rely on their sense of smell to return home during mating seasons to the streams where they were born, which in most cases are thousands of miles away.. Another experiment involves training fish to find an escape route from an artificial net. Not only do fish learn to evade the net rather quickly, if they're placed back there, even a year later, they remember how to get out.
Observations of fish in the wild also suggest that fish use the emotion of fear to anticipate potentially dangerous events and take the necessary precautions to avoid them.
Scientific findings like these suggest that fish indeed have thoughts. Their brains interact with the world around them and informing their memories and present mental state, while also helping them make plans for the future.
Six fast facts about fish
- Fish sleep is similar to human sleep. A 2019 study published in Nature observed zebrafish's brain activity while they were snoozing, leading researchers to discover that the fish demonstrated two sleep stages: "slow bursting sleep" and "propagating wave sleep." The two distinct levels of sleep bore striking resemblance to humans, who slip first into slow-wave sleep, followed by rapid eye movement [REM] sleep, the stage in which dreams occur.
- Fish can do math. In an experiment carried out in 2022, scientists trained fish to associate blue and yellow colors with the commands "add one" and "subtract one" respectively, showing that fish were capable of successfully performing basic arithmetic.
- Some fish are electroreceptive. Certain fish species can use to electricity to communicate with others, hunt or just make there way around. Sharks are particularly sensitive to electric waves, able to detect the charge of a single flashlight battery connected to electrodes 16,000 kilometers apart. Some fish have good electricity etiquette too, changing their own electrical frequency when swimming past another fish with a similar frequency, to avoid confusion.
- Fish are tool users. It's hard to be handy when you only have fins, but that hasn't stopped the tuskfish, who became the first fish to be observed using a tool, as well as clever problem-solving, to accomplish a task. Various clips of underwater footage show tuskfish cracking open clamshells by launching them against nearby rocks.
- Goldfish have good memories. There's a pervasive global myth that goldfish and other common pets only have three-second memories. Thanks to some simple scientific tests, however, this myth is easy to debunk. Experiments usually involve training goldfish to associate some kind of stimulus—it could be a color, bubbles or music—with a reward. Long after the studies have ended, these fish will continue to associate positive stimuli with a positive outcome.
If fish can feel, what’s next?
Despite the wealth of information at our fingertips about fish and their cognitive, emotional capabilities, the commercial fishing industry and factory fish farms have continued to force fish to endure cruel treatment every day. Worse yet, many governments around the world have still not afforded fish the same basic rights as other animals. Science has shown us that fish have feelings, so what's next? Join thousands of other compassionate animal rights advocates in fighting back against the factory farming industry's cruelty toward fish.
