Rapid Progressive Social Development of Zebrafish.

Zebrafish (Danio rerio) are highly social animals that engage in a diverse variety of nonreproductive social behaviors that emerge as early as 14 days postfertilization (dpf). However, we observe considerable behavioral variability at this stage, and comparisons across studies are potentially complicated both by chronological gaps in measurements and inconsistencies in developmental staging. To address these issues, we adapted our assay for social orienting and cueing in the adult zebrafish and used it to probe behavior in a critical window of larval development. In addition, we performed measurements of body length and tested a cohort of larvae with impaired growth to understand if this morphological feature is predictive of individual sociality. We report that zebrafish exhibit increasingly complex social behaviors between 10 and 16 dpf, including place preference, orienting, and social cueing. Furthermore, social behavior is related to standard length on an individual basis beginning at 14 dpf, such that developmentally stunted 14 dpf zebrafish raised on dry feed do not exhibit social behaviors, suggesting some morphological features are more predictive than chronological age. This highly variable and early stage in development provides an opportunity to further understand how genetic and environmental factors affect the assembly of neural circuits underlying complex behaviors.