Anaesthetic Qualities of Eugenol and 2-Phenoxyethanol and Their Effect on Same Haematological Parameters in Farmed European Sea Bass (Dicentrarchus labrax L.)

To gain more knowledge on the anaesthetic characteristics of 2-phenoxyethanol and eugenol in fish, this study investigated induction and recovery when administering these substances in increasing concentrations to 240 adult farmed European sea bass (Dicentrarchus labrax). Levels of serum cortisol, serum glucose and haematocrit value were recorded in order to evaluate the effects of the anaesthetic substances on haematological indicators of stress in fish. The anaesthetic responses showed the notable power of Eugenol; the induction phase was rapid and subjects reached deep anaesthesia in significantly shorter times compared to 2-phenoxyethanol. The subjects anaesthetized with Eugenol tended to recover very slowly even at low concentrations in comparison with the fish treated with 2-phenoxyethanol which always recovered rapidly. The blood parameters showed few statistically significant differences between control and anaesthetized fish with an irregular trend between the groups tested except for the haematocrit values which were in three of the four trials with Eugenol, statistically higher in the control fish compared with the anaesthetized fish. The results of this study suggest that the anaesthetics used do not substantially affect the evaluated blood profile in the sea bass.