Essentials Oils as an Alternative for the Euthanasia of Penaeus vannamei

Introduction: The rapid expansion of crustacean production in Brazil has increased the demand for humane slaughter methods to improve animal welfare and meat quality. Traditional methods, such as hypothermia-induced euthanasia, have been re-evaluated, highlighting the need for less aversive alternatives, such as essential oils (EOs) from Cymbopogon winterianus, Aloysia citriodora, and Lippia alba. Therefore, this study aimed to evaluate the efficacy of different EO concentrations for inducing rapid euthanasia in Penaeus vannamei by monitoring the time to death. Methodology: Essential oils from C. winterianus, L. alba, and A. citriodora were obtained by hydrodistillation and characterized by gas chromatography. Adults Penaeus vannamei shrimp (n = 8) were individually exposed to two concentrations of each EO (1300 and 1500 µL/L for L. alba; 1200 and 1600 µL/L for C. winterianus; and 1400 and 1600 µL/L for A. citriodora), in addition to a group subjected to hypothermia (ice-water slurry). Water quality parameters were monitored throughout the experiment, and data were analyzed using ANOVA followed by Tukey's test (P < 0.05). Results: Hypothermia-induced euthanasia was the fastest method, causing total immobility in less than 30 s. However, significant differences were observed between the EOs tested. Aloysia citriodora EO showed the poorest performance, resulting in prolonged euthanasia times and high stress levels, characterized by agitation and aversive behaviors. In contrast, L. alba EO at 1500 µL/L was the most effective EO treatment, ensuring 100% mortality and promoting rapid induction of deep anesthesia followed by apparent death within a short period. Conclusion: Hypothermia was the fastest method for euthanasia of P. vannamei. Among the EOs tested, L. alba (1500 µL/L) showed the highest efficacy, with 100% mortality and rapid induction of deep anesthesia, highlighting its potential as a promising alternative for the euthanasia of this species.