A study on the shoal structure interaction and behavioural phenomics of social isolation in zebrafish

Abstract

Chronic social isolation is a widely used environmental stress model: however, its behavioural consequences across sexes and levels of social organisation remain insufficiently understood. The present study investigated the effects of prolonged social isolation in zebrafish (Danio rerio) using a multi-level behavioural framework integrating individual assays, stimulus-based social tests. collective shoaling dynamics, dyadic interactions. and descriptive gut microbiome profiling. Open field and light—dark assessments revealed increased locomotor activity and altered anxiety-like responses in isolated fish, with strong bascline sex differences becoming masked under isolation. In three-chamber paradigms, isolation reduced social preference and modified predator- and mirror-induced behaviours in a sex-dependent manner. with partial stress buffering observed in males and reduced buffering efficiency in females. Shoal and dyad analyses demonstrated disrupted spatial cohesion, alignment, and emergent state stability in isolated groups. Descriptive microbiome analysis further indicated sex-specific shifts in gut microbial composition. These findings provide translational insight into how chronic social isolation may contribute to behavioural dysregulation relevant to neurodevelopmental and stress-related conditions.