Fish use a mirror to assess their strength before a fight

A recent study by a team of scientists from Osaka Metropolitan University has shown that sponge fish (Labroides dimidiatus) use a mirror to estimate their size before deciding to attack other fish. These findings reveal the fish's amazing powers of self-perception and analysis, previously thought to be the prerogative of more evolved animals.

In an experiment described in the journal Scientific Reports, gubans demonstrated the ability to check with their mirror image to determine whether to attack fish that are slightly larger or smaller than themselves. This finding suggests that fish have mental processes such as evaluating their own image, purpose and intention, indicating elements of self-awareness.

The research team, including student Taiga Kobayashi, professors Masanori Kohdu, Satoshi Awata and others, continued to study self-awareness in fish following their previous discoveries. Last year, they showed that sponges can recognise themselves in photographs by using a mirror for self-recognition.

This time, the behaviour of the fish turning to the mirror at certain times suggests that they could use it to compare their size with that of other fish and, based on this, predict the possible outcome of a conflict.

These findings open new horizons in the study of self-awareness in animals. The results of the study suggest that sponges are able to use the mirror as a tool, which brings their behaviour closer to humans and other animals with advanced cognitive functions.

The fact that fish can use a mirror as a tool for analysis helps us understand how self-awareness evolved in animals," said Taiga Kobayashi, one of the authors of the study.