Effect of Rosemary (Rosmarinus officinalis) and Sage (Salvia officinalis) Essential Oils on Disease Resistance against Aeromonas sobria in Goldfish (Carassius auratus)

Abstract

In this study, the chemical composition and the antibacterial properties against Aeromonas sobria of the essential oils of rosemary and sage in gold fish were evaluated in vitro and in vivo for the first time. The major constituents were eucalyptol (26.36%) and camphor (29.17%) for rosemary essential oil and eucalyptol (27.08%), thujone (20.52%) and camphor (16.99%) for sage oil. In vitro antibacterial effects of essential oils against A. sobria were detected by agar diffusion assay. The in vitro antibacterial effect of rosemary (20±2.82 mm) and sage (18.5±2.12 mm) essential oils (1000 µl ml-1) were determined to be strong against A. sobria (p˂0.05). The effects of the essential oils on the disease resistance of goldfish were also investigated. Fish (5±0.15 g) were fed with different concentrations (0, 1.0 and 3.0 ml kg-1) of each essential oil for 45 days. After feeding, the fish were challenged with A. sobria. Dietary administration of sage essential oil (1.0 and 3.0 ml kg-1) and rosemary oil (3 ml kg-1) resulted in a significant reduction in mortality due to A. sobria compared to control fish. Our results suggest that these plant oils could provide an alternative for A. sobria infection control in aquaculture.