Efficacy, Physiological Response, Flesh Quality and Carvacrol Residue of Oregano Essential Oil as Anesthetic for Spotted Sea Bass (Lateolabrax maculatus)

Oregano essential oil (OEO) was tested as a natural botanical anesthetic for spotted sea bass (Lateolabrax maculatus) through a comprehensive evaluation of anesthetic efficacy, physiological homeostasis, tissue integrity, flesh texture and carvacrol residual dynamics. Gradient treatments (100–300 µL/L) revealed dose-dependent anesthetic performance, and 200 µL/L was validated as the optimal dosage, under which fish reached deep anesthesia within 3 min and regained normal swimming within 5 min, with zero mortality recorded 12 h post-anesthesia. Temporary stress and oxidative stress fluctuations occurred in serum biochemistry and antioxidant enzyme profiles, which approached control levels after 12 h depuration. Only slight histological changes appeared in liver and gill tissues without permanent pathological damage. Minor declines in partial texture attributes recovered completely within 12 h, whereas other muscle quality indicators remained unaffected. Carvacrol was detected in muscle immediately after OEO anesthesia but was below the detection limit at all subsequent sampling times. Functioning as an efficient natural anesthetic with minimal physiological disturbance, OEO shows potential as an alternative to synthetic anesthetics for spotted sea bass live transportation and delivers dependable technical guidance for aquaculture production.