Dopamine and serotonin mediate the impact of stress on cleaner fish cooperative behavior.

Stress is known to modulate behavioral responses and rapid decision-making processes, especially under challenging contexts which often occur in social and cooperative interactions. Here, we evaluated the effects of acute stress on cooperative behavior of the Indo-Pacific cleaner wrasse (Labroides dimidiatus) and the implications of pre-treatment with monoaminergic compounds: the selective serotonin reuptake inhibitor - fluoxetine, the 5-HT1A receptor antagonist - WAY-100,635, the D1 receptor agonist - SKF-38393, and the D1 receptor antagonist - SCH-23390. We demonstrated that stress decreased the predisposal to interact and increased cortisol levels in cleaners, which are alleviated by fluoxetine and the dopaminergic D1 antagonist. Overall, our findings highlight the crucial influence of stress on cooperative behavior.