Comparison of anaesthetic effect of clove oil, saline solution and colloidal solution in juvenile Chirostoma jordani (Woolman, 1894)

Abstract

The fish Chirostoma jordani undergoes intense stress during handling practices, making it susceptible to disease and high mortality rates. The objective of this study was to compare the anaesthetic effects of clove oil, saline solution and colloidal solution (Pentabiocare) on juvenile Chirostoma jordani. 18 C. jordani specimens aged two months old were used for each treatment. Treatments consisted on clove oil at four concentrations (5, 8, 13 and 25 µL/L), saline solution at 7 g/L and colloidal solution at 5 mL/L. The anaesthesia stages and recovery time of fish were recorded during a six hour period. High concentrations of clove oil and prolonged exposure to it were associated with deep stages of anaesthesia. Clove oil in a concentration of 25 µL/L induced fish to stage three and after three hours of being exposed they entered stage five, while those sedated with saline and colloidal solutions were induced to stage one and showed the longest sedation times (six hours). Recovery time in juveniles when using 25 µL/L clove oil concentration was extended to 3,006.0 ± 5.3 seconds, while fish exposed to saline and colloidal solution showed a recovery of opercular rhythm, responsiveness to external stimuli and active swimming within 60 to 180 seconds. The results indicated that colloidal and saline solution kept the C. jordani juveniles in a state of light sedation during a six hours period with brief intervals of recovery. The use of clove oil at 5 and 13 µL/L doses induced juveniles to light and deep anaesthesia stages, respectively, with a recovery time under 420 seconds.