Can we use judgement bias to assess the welfare of fish in aquariums and zoos?

This commentary examines the potential of tests of judgment bias to assess fish welfare in aquariums and zoos. Judgment bias offers a non-invasive approach to interpreting affective states in animals, using cognitive responses to ambiguous stimuli as indicators of mental wellbeing. Despite the constraints of captive environments—such as limited handling and species diversity in exhibits—recent adaptations of judgment-bias protocols make them suitable across taxa, including fishes. Collaborations with progressive zoos and aquariums could facilitate this research, based on the shared goal of enhancing animal welfare and promoting public education.