Fish: Sentient, Conscious Beings Hidden from Our Sight

X Facebook WhatsApp

Often misunderstood as forgetful and insensitive, are fish really just simple creatures? Recent scientific findings suggest that fish have a much more complex existence and awareness than previously thought.

Fish are often discussed in the same impersonal way as metals, clothes, and other inanimate goods. Terms like “fish resources” and “cod stocks” permeate discussions about the ocean, from scientific papers to NGO reports and political debates.

Why the 12-5-30 Incline Walking Method Is the Ultimate Fat-Burning Workout, According to Fitness Experts

The ultimate trick to banish mold from your bathroom grout in just 7 minutes—no vinegar or baking soda needed

The upcoming United Nations ocean conference in Nice this June is no exception. Countries will consider how to “manage” fish “stocks” to restore them to “levels” that allow for “maximum sustainable yield”… as if discussing machines rather than living beings. Does this approach do justice to fish, whose capabilities continue to surprise researchers?

Just as plant biology has reshaped our view of trees, recognizing their communication abilities, recent studies on fish cognition are challenging the long-held belief that fish are unintelligent. This idea dates back to ancient times; Aristotle in 4th century BCE Aegean Greece believed fish were inferior to humans and other mammals.

Even today, fish are often thought of as lacking intelligence, social bonds, and sensitivity to pain—positioned low on the hierarchy of life, on shores where our empathy fears to tread. “Humans have lived for thousands of years with cows, sheep, etc. But fish live out of sight, and therefore out of mind,” notes ecologist Culum Brown, a professor at Australia’s Macquarie University and a leading expert on the subject.

“They don’t have facial expressions, which humans rely heavily on to understand each other,” adds Lynne Sneddon, a professor at the University of Gothenburg in Sweden and a renowned fish specialist. “They also don’t vocalize in frequencies that we can hear. Those who spend a lot of time with them know they lose interest in food when something is wrong, their color changes, or their fins droop. But without quality time with them, it can be difficult to feel empathy.”

While prejudices persist, science has “evolved very rapidly,” says ethologist Jonathan Balcombe, author of a book on fish cognition. In the last decade, a surge of studies has emerged on the mental and emotional faculties of fish: 68% of such studies were published between 2010 and 2019, highlights a recent review.

This burst of research reveals the complexity of fish and their perception of the world. Consider one of the major stereotypes about them: their memory lasts only three seconds. Numerous studies have shown otherwise. In 2013, for example, researchers demonstrated that frillfin gobies, at high tide, create mental maps of the rocky pits where they live. They remember the location of their pools even after being removed for forty days and displaced by thirty meters.

Pikes tend to avoid hooks for over a year after being caught; rainbowfish that are given time to find an escape route from a net remember the path even a year later, despite only living for two years in the wild.

Even more fascinating, in 2016, a team from the universities of Oxford and Queensland discovered that archerfish—tropical fish known for knocking down prey by spitting jets of water—could learn to recognize a human face and distinguish it among forty-four others, “even though they never encounter humans in the wild,” marvels Jonathan Balcombe.

Research has uncovered the existence of social bonds, learning networks, and traditions underwater. A study showed that Atlantic salmon raised in fish farms—thus inexperienced hunters—could learn to catch new prey by watching experienced peers.

Cooperation is also significant in their lives. Moray eels and groupers sometimes hunt together, with the former scaring prey so the latter can more easily catch them, and vice versa. This type of mutualism is extremely rare in the animal kingdom, especially between different species, and is comparable to the relationship between dogs and humans, notes Culum Brown.

Another well-known case of cooperation involves the cleaner wrasse. This slender-bodied fish operates “cleaning stations” in coral reefs, where it removes parasites, cleans gills, and scrubs teeth for its “clients”—groupers, moray eels, and rays. In return, it feasts on their dead skin.

Diving into the plethora of publications on this species, we learn that its members recognize their (many) regular clients individually and manage their affairs strategically: in case of a queue, they prioritize transient fish, as locals are less likely to go elsewhere. Predators also receive preferential treatment and are less likely to be bitten during their session.

In case of an accidental bite, the wrasses may offer back massages as compensation. A study on surgeonfish showed that their physical contact with wrasses reduced their stress levels, a phenomenon previously documented only in humans.

That’s not all. In 2019, a team demonstrated that the cleaner wrasse passed the “mirror test,” used to assess self-awareness in animals. Scientists placed a red dot on the bodies of the fish and then positioned them in front of a mirror. The fish quickly began scratching on the floor, as if to remove the mark—a behavior they did not exhibit in the absence of a mirror. Culum Brown considers this one of the most exciting discoveries in the field.

The fact that a fish passed this test—a feat previously achieved only by a handful of mammals and birds—sparked controversy, with some researchers accusing the team of conducting poor science, or arguing that this method, used since the 1970s, was not suitable for assessing an animal’s consciousness.

Lynne Sneddon sees this as a form of “speciesism”: “If an elephant had moved its trunk in front of a mirror, everyone would have thought it was wonderful.” “It shows that there are strong biases against fish, not only among the general public but also among scientists,” agrees Culum Brown. “We always expect them to be less intelligent. But nine times out of ten, they turn out to be capable of the same things as mammals.”

Their pain pathway, in particular, is remarkably similar to ours. “They have the same nervous system, the same hormones, the same neurotransmitters…” It is “highly probable,” according to the scientist, that we inherited these mechanisms from a common fish ancestor.

More than 70 studies published in international scientific journals show that fish feel and respond to pain, points out Lynne Sneddon, who was the first to prove the existence of nociceptors (a pain receptor) in fish. “And it’s not just a simple reflex response, but a radical change in behavior: they no longer have anti-predator responses, may seek substances to relieve them…”

This wealth of evidence has so far had limited impact on how we treat them. “Sticking our heads in the sand and pleading ignorance gives us an excuse to mistreat them,” suspects Culum Brown. A hypothesis consistent with the findings of psychology researchers, suggesting that humans tend to “other” those they consider appropriate for their consumption.

The researcher cites the example of trawling. The suffering this fishing technique inflicts on fish would never be accepted for mammals. “They try to swim ahead of the net, but they get exhausted and end up crushed by others. The pressure change when they are brought to the surface causes considerable injuries: their bladders burst, their eyes pop out… Many suffocate. And the ice they are thrown onto only prolongs their suffering.”

Some ships and aquaculture farms try to limit the damage by stunning fish after capture, but this approach remains very much in the minority. For the vast majority of the approximately , pain and indifference remain the norm. “Fish are anonymous statistics to us,” observes Jonathan Balcombe. He hopes that science will pave the way for a change in perspective and the recognition of each fish as a sensitive, complex, and unique individual.

Receive daily, free of charge, all the news about ecology directly in your mailbox.