This fish reveals an unsuspected “self-awareness”

The latest research reveals that certain fish have developed a remarkable form of social intelligence.

The cleaner wrasse (Labroides dimidiatus) has surprised researchers with its ability to use a mirror to observe itself. These fish measure about 4 inches (10 centimeters) and passed the famous mirror test in 2018.


Recently, a team led by Taiga Kobayashi from Osaka Metropolitan University delved deeper into this question. Their study, published in Scientific Reports, shows that these fish don't just recognize their reflection, but also use it to evaluate their own size.

The researchers observed the wrasse in an aquarium. In an initial series of experiments, the fish were exposed to images of wrasse larger or smaller than themselves. They consistently chose to fight, regardless of the size of the opponent.

In the second experiment, a mirror was added. When the fish could observe themselves, their behavior changed: they showed aggression only towards wrasse smaller than themselves. However, the mirror was not placed next to the images of the other fish, meaning the wrasse first analyzed their own size, constructed a mental image of that size before comparing themselves to rivals to decide whether to attack or not.

The results suggest that wrasse possess a form of “self-awareness.” They use their reflection to anticipate the outcome of a potential confrontation. Indeed, having an accurate perception of their own size could give them an advantage by avoiding fights they cannot win.

The research team emphasized that these behaviors reveal complex mental states in wrasse. The fish display intentions and goals, key elements of individual consciousness. This finding could also shed light on the evolution of consciousness in other animal species.

By analyzing these interactions, scientists hope to better understand the mechanisms of consciousness in animals. These discoveries open the door for further studies on fish cognition and their social interactions. Research on wrasse continues to surprise with the complexity of their behavior.

What is self-awareness in animals?

Self-awareness in animals refers to their ability to recognize and understand their own existence. This includes the ability to recognize their reflection in a mirror and to make comparisons with other individuals. This form of awareness may involve more complex cognitive processes, such as the ability to plan actions based on their body image.

Studies on species like the cleaner wrasse have shown that these fish can construct a mental image of their size, influencing their social decisions. This self-assessment allows them to determine if they can win a fight, which reveals social intelligence and an understanding of their place in the environment.