A new study reveals that emperor cichlid fish, a large species native to Lake Tanganyika in Africa, can detect when they are being watched – and they don’t appreciate it, especially when their offspring are the focus of attention. The findings, published in the journal Royal Society Open Science, suggest these fish possess a surprising level of cognitive ability and awareness of their surroundings.
Researchers from Japan conducted the experiments directly in the emperor cichlid’s natural habitat. The study aimed to determine if the fish could differentiate between various types of human gaze. Understanding how animals perceive and react to observation is crucial for minimizing stress and ensuring their well-being, particularly as human interaction with wildlife increases.
The emperor cichlid, which can grow up to 80 cm in length, is known for its aggressive behavior when protecting its young. This made it an ideal species for the research. Scientists wanted to see if the fish would react differently depending on where a diver’s gaze was directed.
The research team used scuba divers as “observers” and observed the fish’s reactions in a series of scenarios:
- The diver directly stared at the fish’s eggs or offspring.
- The diver was near the nest but looking in a different direction.
- The diver turned their back to the nest, but their body was still oriented towards it.
- The diver stared at the parent fish, rather than the offspring.
All interactions were recorded with underwater cameras, and each diver conducted the experiments individually to avoid influencing the fish’s response.
The results were striking. The fish exhibited significantly more aggressive behavior when the diver directly focused their gaze on the eggs or young. This was in contrast to when the diver looked away or wasn’t focused on the nest. Interestingly, the level of aggression was similar whether the diver was looking at the offspring or the parent fish.
“Our findings suggest that fish may be involved in more flexible cognitive processes—namely, the ability to infer where the attention of other individuals is directed,” researchers stated in the report. This indicates the fish aren’t simply reacting to a presence, but rather interpreting the intent or focus of attention conveyed through eye gaze.
The study also carries implications for human activities, particularly in marine tourism. As scuba diving becomes increasingly popular, human interaction with marine life is becoming more frequent. However, a seemingly harmless gaze from a human can trigger stress or defensive responses in animals.
Researchers caution, “With the increasing popularity of scuba diving as a form of marine ecotourism, such stress effects need to be evaluated alongside physical impacts such as habitat damage.”
This research adds to a growing body of evidence demonstrating that animal cognitive abilities are often underestimated—even in species traditionally considered simple, like fish. The emperor cichlid demonstrates that understanding social cues, including recognizing the attention of others, isn’t limited to mammals or birds.
And for humans, it serves as a simple reminder: even underwater, your gaze can matter.
