Do fish have feelings? Maybe we're getting closer to answering.

Fish are conscious, and the evidence that they are able to feel pain in a similar way to humans is gradually increasing. Research suggests that some species can learn, form relationships and experience pain. In a recent experiment, a tag was placed under the neck of a number of fish when they were drugged, so they would not notice. When placed in front of a mirror, the fish guided their bodies to see the mark, and tried to rub it by scraping themselves on the rocks, indicating that they recognized themselves in the mirror. In this article, we show some scientific experiments conducted on fish, which clearly show signs of their awareness. And the impact on our attitude towards it.

Before that:

There are compelling reasons to include fish in our "moral circle" and give it the protection it deserves. In 2011 an interesting experiment found that fish relieves their stress by soothing physical contact. The researchers studied the surgeonfish that lives in coral reefs and found that they frequently visit a smaller fish known as cleaned headfish. The two species share a mutually beneficial relationship where cleaned headfish eat parasites and dead skin from surgeonfish. In the experiment, scientists showed a group of surgeon fish to models of mechanically moving cleaned headfish, while another group of surgeon fish was exposed to immobile head fish models. Surgeon fish gently petted and stimulated by mechanical models had significantly lower levels of cortisol — a stress-related hormone — than those whose models were consistent. Studies like this show us that fish feel comfortable and relaxed through physical contact, similar to how massage therapy can help people's mental health.

What emotions do fish experience?

On the surface, fish and humans seem to have very little in common. But looking beyond the surface differences, scientists have discovered that fish exhibit emotions similar to those we experience. One of them is the feeling of enjoyment. Aquarium-dwelling fish roam through bubble streams as if riding roller coasters, and rays jump out of the water several meters into the air with no apparent purpose other than pure enjoyment. Fish can also be precise in choosing a companion, and when they break up with their chosen partner, they become more pessimistic. A 2019 study discovered this by introducing two potential fish companions and allowing them to choose a favorite. Some females were paired with males they chose, while others were unlucky stuck with males they rejected. During the experiment, fish that did not get their desired partner showed less optimism overall. There is also evidence that fish are able to feel fear. The researchers tested this by exposing trout to scary stimuli and flooding a net in a trout tank whenever a certain light was on. Trout learned to associate this light with the creepy net, and would run to safety when the light was on, even before the net was submerged in the water. This fear remained with trout for at least a whole week.

Do fish suffer from pain?

Yes, fish suffer from physical and emotional pain. Scientists say it's probably a different kind of what humans experience, but it's pain anyway. Fish have nerve endings called pain receptors that alert their bodies to potential damage such as high temperatures, extreme stress, and harmful chemicals. Fish also produce the same natural painkillers as mammals, called opioids. Like mammals, birds and other vertebrates living on Earth, fish are exposed to a rush of electric currents that pass through their brains when they are hurt. Unfortunately, many of the methods used in commercial fishing expose fish to both types of suffering, physical and emotional. A 2019 study found that cod and haddock caught with trawlers remained conscious until two hours after being pulled out of the water.

Does fish feel pain when caught with a hook?

Fish undoubtedly feel pain when attached to a fishing rod; fish have a high concentration of pain receptors in and around their mouths and lips, where they are usually pierced with a hook. One study found that when trout was subjected to a painful stimulus, their behavior and physiological functions changed for a long time, suggesting they felt the effects of pain. Whereas, when injected with morphine — a pain-relieving drug — in addition to the painful stimulus, her behavior and physiological functions remained normal. This shows that exposure to pain changes her mental state, similar to what pain does to humans and other mammals.

Do fish have ideas?

In humans, the idea is for our brains to represent something that we have perceived with our senses, felt with our emotions, or shaped as a plan of action. Many thoughts are "stored" in our brains as memories. Scientific experiments have proven that fish are able to store important information about their surroundings in their memory, and act accordingly. Salmon, for example, can rely on their sense of smell to return to their habitat during mating seasons to the streams where they were born, which are often thousands of kilometres away. Another experiment involves training the fish to find a way to escape from an artificial web; they learn to evade the net quickly, and remember how to do so if they are placed there again, even after a year.

Five quick facts about fish:

1- The sleep of fish has stages similar to human sleep.

2- Fish can perform some basic calculations.

3- Some fish, such as sharks, are sensitive to electric waves, and change their electrical frequency when swimming next to another fish with the same frequency, to avoid confusion.

4- Some fish use tools; tuskfish open shells by releasing them into nearby rocks.

5- Goldfish have a good memory.

The end:

If fish can feel, then what? Despite the abundance of information at our disposal about fish and their cognitive and emotional abilities, commercial fishing and industrial fish farms continue to force fish to endure harsh treatment every day. It is time to give fish the same basic rights as other animals.