Social cognition in fishes

•We summarize recent advances in research on fish social cognition.•Social decision-making networks in the brain are conserved among vertebrates.•Radiations in fishes are ideal for linking ecology and brain evolution.•Fishes are model systems for studying the physiology of cognition.•Fishes are model systems for studying cooperation and social decision making.

Brain evolution has often been correlated with the cognitive demands of social life. Further progress depends on our ability to link cognitive processes to corresponding brain part sizes and structures, and, ultimately, to demonstrate causality. Recent research suggests that fishes are suitable to test general hypotheses about vertebrate social cognition and its evolution: brain structure and physiology are rather conserved among vertebrates, and fish are able to perform complex decisions in social context. Here, we outline the opportunities for experimentation and comparative studies using fish as model systems, as well as some current shortcomings in fish social cognition research.