AITC fish (n = 26) presented a lower angular velocity compared to controls (n = 25, p=0.002), an effect reversed in fentanyl/AITC group (n = 16, p=0.001). This effect was blocked by naloxone at 20 and 50 µM (n = 12 and 17, p=0.002 and p=0.004), but not by CTAP (n = 11, p=0.812). Angular velocity in fentanyl group (n = 9) was significantly higher than AITC, fentanyl/AITC, naloxone/AITC/fentanyl, and CTAP/AITC/fentanyl (all p>0.05). Data are presented as medians ± 75% and 25% percentiles. Black bars represent medians significantly different with p<0.05. Source data can be found in Figure 6—source data 1.