Young guppies who were able to see and interact with live fish developed larger brains than guppies who only saw other fish on a screen. This is shown in a new study from Stockholm University, published in Biology Letters . The findings suggest that live social interaction in real time may be important for brain development.
“Our results suggest that it is not enough to simply see social cues. The interaction itself, the fact that another individual responds to you in real time, appears to be important for normal brain development,” says Olivia Carmstedt, first author of the study, who carried out the project as part of her master’s thesis.
The research group at the Department of Zoology, Stockholm University, investigated how different types of social experience affect brain development in young guppies. Over a period of 20 days, the fish were raised under one of three conditions: with visual contact with live fish, with video recordings of fish on a screen, or with very limited social contact.
The fishes who had contact with live fish developed brains that were almost six percent larger than those of fish who only saw other fish on a screen. They also had relatively larger olfactory bulbs, a brain region important for instance in social information processing. The brains of fish who had only seen other fish on a screen were more similar to the brains of fish with minimal social exposure than to those of fish who had experienced live social contact.
The study was conducted on guppies, but was partly inspired by growing concerns about how increasing amounts of passive screen usage may affect brain development in humans, especially children. A large number of studies on humans show associations between screen use and brain development, but they cannot reliably establish what causes what. By using fish, the researchers were able to experimentally control the social environment and compare the effects of interactive and non-interactive social exposure.
“Fish are excellent models for studying brain plasticity because their brains continue to develop throughout life. While humans and fish are obviously very different, the basic principle that social interaction can influence brain development appears to be deeply shared across vertebrates,” says Niclas Kolm, senior author of the study and professor at the Department of Zoology, Stockholm University.
After the treatment period, the fish were tested in an object permanence task, that is, the ability to track an object that temporarily disappears from view. The researchers found no difference between the groups. The result suggests that some aspects of brain development may be more sensitive to social experience than others.
“We want to emphasize that the findings do not show that all screen use is harmful. Instead, the study highlights the importance of interactive social experiences during development,” says Olivia Carmstedt.
About the study
The article “ Streaming for fish? Screen-based social exposure disrupts brain development ” is published in Biology Letters .
DOI: 10.1098/rsbl.2025.0830
Biology Letters
Observational study
Animals
Streaming for fish? Screen-based social exposure disrupts brain development
3-Jun-2026
The researchers declare no competing interests.