2.4.1. Novel Tank Diving Test (NTT)

NTT is a specific test used for assessing anxiety in zebrafish, as described by Cachat et al. [25]. The trapezoidal tank (1.5 L) used measured 15.2 cm (height) × 27.9 cm (top) × 22.5 cm (bottom) × 7.1 cm (width), equally divided into two horizontal sections (top and bottom). After 60 min of REO treatment, the animals were placed individually within the test tank without acclimatization, and swimming behavior was recorded for 6 min. The animals were recorded with a Logitech HD Webcam C922 Pro Stream camera (Logitech, Lausanne, Switzerland) placed 30 cm away from the tank and the videos were analyzed using ANY-Maze® software (Stoelting CO, Wood Dale, IL, USA). The following parameters were registered: the number of entries in the top/bottom zone of the tank, total distance traveled in the tank (m), and average velocity (m/s).
