A recent study reveals that wild fish can distinguish between people based on their clothing colors. Surprisingly, this discovery could change how humans perceive and treat these underwater creatures.

Fish Can Tell Humans Apart

While researchers have long known that domestic animals and those living close to humans can recognize individuals, this skill in wild animals is less common. Typically, animals use this ability to find food or avoid danger. However, scientists were surprised to find that wild fish also possess this skill.

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Researchers from the Max Planck Institute of Animal Behaviour in Germany discovered that wild fish could differentiate between two people by observing their outfits. “They are just using simple mechanisms that they use every day in their lives, and they adapt it to [recognise] humans,” said lead researcher Maëlan Tomasek.

How Researchers Conducted the Study

To explore this further, the study was conducted in the open waters of the Mediterranean Sea. Initially, a researcher spent 12 days training wild saddled seabream and black seabream. She repeatedly offered food and rewarded the fish that followed her when she swam away.

Then, a second researcher joined the experiment. The two wore either matching diving gear or outfits with distinct-colored patches and fins. They swam in different directions, later returning to the starting point and repeating the process. Although both divers carried food, only the fish that followed the trainer received rewards.

The researchers conducted 30 trials for each outfit variation. Additionally, they used video recordings to count how many fish followed each diver. Notably, when the divers wore different outfits, both fish species often chose to follow the trainer. Moreover, this preference became more pronounced as the trials progressed.

Fish Showed Learning Ability

Interestingly, the study showed that some fish improved at choosing the trainer over time. This finding indicates that fish were not only recognizing the trainer but also learning from their experiences.

However, when the divers wore identical outfits, the fish struggled to differentiate between them. Black seabream showed no preference, while saddled seabream only followed the trainer during the middle phase of the trials. “All in all, when we wore the same outfit, we have no evidence that they could discriminate between us any more,” said Tomasek.

Simple Visual Cues Help Fish Recognize Humans

According to the researchers, fish likely use basic visual cues, such as patterns and colors, to tell humans apart. Since these wild fish had no prior experience with humans, their ability to adapt using simple recognition techniques is remarkable.

“It shows very simple mechanisms, like pattern recognition or colour recognition can be used, and co-opted to be used, in human recognition,” Tomasek explained.

A Call for Greater Compassion

Ultimately, Tomasek hopes this study will prompt people to rethink their attitude toward fish. He suggested that if fish can recognize humans, then perhaps humans should treat them with more empathy.

“It’s very human to not want to care about them, but the fact that they can care about us, maybe it’s time that we can care about them, too,” he said.

Overall, the study offers fresh insights into the intelligence of wild fish. Furthermore, it emphasizes the need to reconsider how we interact with animals in their natural environments.