Effects of three anesthesia and two tranquilizers’ protocols on stress response during handling in tilapia (Oreochromis niloticus)

To determine the effect of anesthesia and tranquilization on the stress response of tilapia (Oreochromis nilotica) during a handling procedure. We assess three anesthetics: ketamine, MS222, and clove oil; and two tranquilizers: xylazine, and medetomidine, which were administrated by submersion in adult tilapia. Our results showed a significant difference in cortisol levels between treatments after handling procedure (P = 0.0002), where xylazine had the highest cortisol levels compared to the other treatments. We also found differences between induction and recovery times in the different treatments. Then, animals exposed to xylazine took longer to present induction effects, than the other treatments (P < 0.0001). For recovery times, ketamine presents the longest recovery times, than clove oil and MS222, but not when compared to animals exposed to medetomidine and xylazine (P = 0.0019). We observed paleness in animals exposed to medetomidine.