LAUSR

Abstract This study investigates the impact of two types of anesthetics, tricaine methanesulfonate (MS-222) and eugenol, in the gills of juvenile Lateolabrax maculatus. Fish (Mean ± SD, 98.1 ± 7.3 g) were randomly exposed to three treatments, MS-222 (50 mg/L), eugenol (10 mg/L), or anesthetic-free water (control), each with five replicates. Gills were sampled at 0, 1, 3, 6, 12, 24, and 48 h after exposure to the above anesthetics for 20 min. MS-222 and eugenol both had significant immunomodulatory effects on gills. Physiological assays revealed that MS-222 and eugenol induced apoptosis and oxidative stress and changed the morphology of the gills as well as the Na+-K+ flux crossing the gill membrane. These results suggest that immune and physiological responses can be used to evaluate the negative impact of anesthetics on gills.