Behavioral and acetylcholinesterase responses to auditory enrichment in zebrafish exposed to conspecific alarm substance

Stress is an essential physiological response for survival, but when intense or persistent, it can compromise neurological and behavioral functions. Music, on the other hand, is recognized as a sensory stimulus with the potential to modulate emotional states. In this study, we investigated the effects of exposure to classical music on behavioral and physiological parameters in zebrafish subjected to acute stress induced by conspecific alarm substance (CAS). Zebrafish (N = 14-16 per group) were exposed to conspecific alarm substance (CAS) with or without auditory enrichment (classical music). Behavioral responses were assessed across fear-related, anxiety-like, exploratory, and locomotor domains, and whole-body acetylcholinesterase (AChE) activity was measured as a systemic index of cholinergic function. CAS exposure induced robust fear-related and locomotor alterations, accompanied by changes in whole-body AChE activity. Music exposure modulated locomotor and exploratory behavior but did not restore classical anxiety-related parameters. These findings indicate that auditory enrichment influences specific behavioral domains and is associated with alterations in AChE activity, though mechanistic interpretations remain limited by the use of whole-body assays.