Matsuo, S.; Yokoyama, T.; Satoh, S.; Yoshio, Y.; Fukuda, K.

Pharmacological approaches are increasingly used in fish ethological studies to investigate the proximate mechanisms underlying behavior. However, an injection-based administration can induce stress or injury, potentially interfering with natural behavioral patterns. Here, we present a non-invasive vehicle for oral administration. To demonstrate its utility, the oxytocin receptor antagonist atosiban was administered orally using this vehicle and subsequently detected in blood plasma via high-performance liquid chromatography. Our method offers an easy-to-use and minimally disruptive tool for fish behavioral experiments.