Do Fish Have Feelings? Some Scientists Think They Do

Researchers have found evidence that fish can display what's known as "emotional fever."

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Zebra danios were shown to display emotional fever when exposed to a stressful environment. Via Wikipedia
John Virata

All fish, for the most part, are cold blooded. And they lack a cerebral cortex that enables other so-called smarter animals, such as mammals, to process more complex information, but can fish feel emotions? Some scientists say they can.

A study, published in the Proceedings of the Royal Society B: Biological Sciences, found that the zebra danio, or zebra fish, can feel emotion. Not in the sense that they cry and laugh, but that when they feel uncomfortable, they can let their feelings be known by moving. The researchers pointed out that emotions have been documented in animals such as mammals and birds, but never fish. Until now.

Zebrafish (Danio rerio) aquarium fish

By studying zebra fish exposed to a stressful situation, researchers say they have proved fish have a capacity for consciousness. kazakovmaksim/iStock/Thinkstock

So how did these scientists figure out that these fish feel emotions? They looked for signs of stress-induced hyperthermia or “emotional fever.”

To do that, they created a special fish tank with different connected compartments that had varying temperatures, ranging from 64 degrees Fahrenheit to 95 degrees Fahrenheit. A control group of zebra fish was placed in water at 82 degrees Fahrenheit, the ideal temperature for these fish. A second group was placed in cooler water and then confined in a net. After 15 minutes, the confined fish were allowed to swim freely through the tank. The researchers found that the fish who had been confined swam into the compartments that had warmer water, which significantly increased their body temperature.

While the fish in the second group weren’t crying, the researchers say they did demonstrate emotional fever. In other words, the confined fish got stressed out, which raised their body temperature, and as cold-blooded animals, had to move to a temperature that matched their internal physiological state.

“This finding removes a key argument for lack of consciousness in fishes,” they wrote.

All science aside, if this YouTube video of man massaging or tickling his blood parrotfish doesn’t show an emotional fish, then we don’t know what does.

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