Differential captivity and experiential conditions and its impact on the behaviour and cognition of Picasso triggerfish (Rhinecanthus aculeatus)

In this study, we compared performance across four behavioural tasks in the same fish species (Rhinecanthus aculeatus), with one group held in long-term laboratory captivity and the other recently caught and temporarily housed at a field station laboratory. The aims of this study were twofold: first, to test whether captivity conditions influence performance in commonly used behavioural and cognitive assays; and second, to evaluate whether any of these tasks could serve as a practical tool for screening behavioural changes over time. The four tests used were a Novel Object Test, Puzzle Preference Test, Emergence Test, and Cylinder Test. We found that recently caught fish were generally more exploratory and more responsive to novel stimuli; however, their responses were object-specific, with increased neophobia towards some objects. Long-term captive fish were more variable in their responses across all tests. In the Emergence Test, long-term captive fish emerged faster but showed greater individual variability. In the Cylinder Test, all recently caught fish failed to swim around a transparent cylinder, whereas several long-term captive individuals showed possible evidence of inhibitory control. Our results demonstrate that captivity conditions can influence performance in behavioural tests at both group and individual levels. These findings have important implications for comparative cognition studies, particularly when interpreting results collected across different laboratory settings or captivity durations, even when working with the same species. Of the tasks used, the Emergence Test was identified as the most practical assay for tracking the effects of captivity on behaviour, as it was highly sensitive to individual differences and straightforward to run and analyse.