Simple SummaryVarious studies have assessed animal welfare by analysing how behaviour is affected by environmental and human-related factors. Nevertheless, the combined effects of these factors are poorly researched. This study assessed for the first time the integrated impact of environmental conditions and visitor and caregiver presence on the behaviour of a pair of zoo-housed Asian small-clawed otters. We collected data across 14 sampling days from July to September 2020. We video-recorded the otters’ behaviours using continuous focal animal sampling (42 h of observation/subject). We found that the otters only performed species-specific behaviours and mainly experienced positive welfare states. However, they dedicated less time to locomotion, food-related and affiliative behaviours, and engaged more in vigilance compared to previous studies carried out in captive settings. Interactions between the otters and visitors/caregivers were limited and mostly associated with neutral or positive behavioural responses. Visitor presence and background noise did not affect behaviour. Time of day and animal identity influenced locomotion, vigilance, time spent out of sight, juggling, and visitor–otter interactions. Our results provided meaningful information to improve husbandry practices and highlighted the need to conduct multivariate analysis to better assess the welfare of animals under human care.AbstractZoos and aquaria have the ethical responsibility to provide animals under their care with conditions that promote good welfare. This study evaluated the combined influence of human presence and environmental factors on the behaviour of zoo-housed Asian small-clawed otters (Aonyx cinereus). Data collection was conducted on a pair hosted at Pistoia Zoo (Italy). Data were collected from July to September 2020 (over 14 days). We video-recorded the otters’ behaviours, using the continuous focal animal sampling, obtaining 42 h of observation per subject. The otters displayed a wide array of species-specific behaviours. Compared to previous captive studies, the subjects engaged less in locomotion, food-related and affiliative behaviours, and more in vigilance. Human–animal interactions were limited, and mostly elicited neutral or positive responses, except for begging behaviours performed towards caregivers. Time of day and animal identity were the main significant predictors for behaviours. No effects of visitor presence or background noise were detected. Nonetheless, increasing enrichment use could stimulate food-related behaviours, and reduce vigilance and begging. This study confirms the importance of applying an integrated approach to analyse the complexity of otters’ experiences, and provides insights to guide husbandry improvements.