Chronic inorganic arsenic exposure impairs locomotor performance and socio-affective behavior in zebrafish.

Inorganic arsenic (iAs) is a prevalent and highly toxic environmental contaminant, yet its neurotoxic effects on aquatic organisms are not well characterized. This study examines whether chronic exposure to environmentally relevant concentrations of iAs affects locomotor performance and socio-affective behavior in adult zebrafish (Danio rerio). Zebrafish were exposed to 10, 50, or 300 µg/L of iAs for 21 consecutive days, with behavioral assessments conducted on Days 0, 7, 14, and 21 using standardized locomotor and social preference tasks. Chronic exposure to iAs resulted in time- and dose-dependent neurobehavioral alterations. The most pronounced locomotor effects occurred at concentrations of 50 and 300 µg/L, revealing significant changes in swimming velocity, immobility duration, and counter-clockwise rotations, which indicate disrupted swimming patterns and altered decision-making behavior. Additionally, in the social task, chronic iAs exposure diminished social preference, evidenced by reduced time spent in the social arm and broader shifts in maze-arm exploration, highlighting a dose-dependent disruption of socio-affective behavior. Overall, chronic exposure to environmentally relevant concentrations of iAs is linked to neurobehavioral impairments that affect locomotion, exploratory and decision-making behavior, and social interactions in zebrafish. These findings underscore the neurotoxic potential of arsenic in aquatic organisms and emphasize surface-water contamination as a significant ecological and public health concern.