The effect of different doses of eugenol and induction time on the blood cortisol and glucose level in goldfish (Carassius auratus)

In this study, the effect of eugenol concentrations and induction time on the blood cortisol and glucose of gold fish (C. auratus) was investigated. The Experiment was conducted in two parts: first, the goldfish were exposed to 50-150 ppm eugenol over 40-360 s and blood samples were collected. In the second experiment, fish were exposed to 50-175 ppm eugenol and were allowed to reach stages 4 and 5 of anesthesia. Blood samples were collected and used to determine the levels of cortisol and glucose. The Correlation between cortisol or glucose with induction time or eugenol concentration was also investigated. At 50 and 75 ppm eugenol, cortisol and glucose levels were significantly affected by induction time. In 100 and 125 ppm eugenol, cortisol and glucose levels were significantly affected by induction time, eugenol concentration and interaction. In 150 ppm, cortisol levels elevated in line with the induction time. However, there was no significant change in glucose levels. Correlations between cortisol as well as glucose with induction time and eugenol concentration suggested that induction time is the key factor determining cortisol and glucose levels. Induction time is more important than eugenol concentration for blood cortisol and glucose determination in goldfish. Accordingly, goldfish should be anesthetized with high concentrations of eugenol over a short period of time to minimize the stress response.