Cognition in captivity: Investigating learning, anxiety, and brain mass differences between captive and wild fathead minnow

Captive animals are commonly used in laboratory research, however, captive and wild animals often differ, limiting the applicability of laboratory findings based on captive animals to the "real" world. A comprehensive understanding of how captive and wild animals differ is necessary to assess if captive animals are suitable substitutes for their wild counterparts, however, few studies have compared cognition between captive and wild animals. In this study, we compared aspects of cognition between captive and wild fathead minnow (Pimephales promelas) to investigate how life in captivity might impact traits essential to fitness in the wild. Specifically, we assessed aversive learning performance using an associative learning assay and a more complex reversal learning assay, and we also measured anxiety and brain mass. Performance in the associative learning task was negatively correlated with performance in the reversal learning task, suggesting a potential tradeoff. No differences were observed between captive and wild fish in associative learning performance, anxiety, or brain mass, but wild fish were three times more likely to complete the more complex reversal learning task. Aversive reversal learning, which appears to be dampened in captive fathead minnow, may be particularly relevant for appropriate antipredator responses and fitness in challenging or fluctuating environments. We advocate for further research comparing wild and captive animal cognition and urge researchers to exercise caution when generalizing results from captive animals to wild populations.