Aging in zebrafish is associated with reduced locomotor activity and strain-dependent changes in predator avoidance behaviors related to anxiety

Aging is associated with a wide range of physiological and behavioral changes in many species. Like humans, zebrafish exhibit gradual senescence, and thus may be a useful model organism for identifying evolutionarily conserved mechanisms related to aging. Here, we compared behavior in the novel tank test of young (6-month-old) and middle aged (12-month-old) zebrafish from two strains (TL and TU) and both sexes. We find that this modest age difference results in a reduction in locomotor activity and strain dependent changes in predator avoidance behaviors related to anxiety. Older TL fish have an elevation in bottom dwelling whereas older TU fish have a decrease in thigmotaxis. We found no consistent effects of age on either short-term (within session) or long-term (1 day later) habituation to the novel tank. Our findings support the use of zebrafish for the study of how age affects locomotion and how genetics interacts with age to alter the regulation of emotional behaviors in response to novelty. ### Competing Interest Statement The authors have declared no competing interest.