Researchers have discovered that wild fish can distinguish between two people based on their clothing colour. In a study conducted in the Mediterranean Sea, scientists found that certain species of fish preferred to follow one diver over another when they wore different-coloured outfits.
The study involved training wild saddled seabream and black seabream to follow a researcher by offering them food and rewarding those that followed her as she swam away. The trainer was then joined by another researcher dressed in either identical or differently coloured diving gear. The team carried out 30 trials for each outfit and used video recordings to count the number of fish following each diver.
The results showed that when the divers wore different-coloured outfits, both species of fish followed the trainer more often than the other researcher. This preference became more pronounced as the trials went on. However, when the divers wore the same outfit, no significant difference in follow-up was observed for black seabream.
According to Maëlan Tomasek, the study’s first author, the findings suggest that the fish were using simple visual cues, such as pattern recognition and colour recognition, to distinguish between the two divers. The team believes that this ability may be an existing capacity of the fish, rather than a new learning process.
The study’s implications are significant, as it challenges our current understanding of human-fish relationships. Tomasek notes that if fish can care about humans, perhaps we should also care about them. This could lead to a re-evaluation of how we treat fish, including whether or not they should be killed and eaten.
Source: https://www.theguardian.com/environment/2025/feb/19/wild-fish-can-tell-humans-apart-when-they-dress-differently-study-finds