Amyris balsamifera essential oil promotes anesthesia in Colossoma macropomum (Cuvier, 1818): electrophysiological tools in the indication of a therapeutic window.

Currently, anesthesia is widely used in aquaculture, which raises concerns about the choice of anesthetic agent to be administered. Amyris sandalwood essential oil has muscle relaxant characteristics due to its chemical composition, which indicates its potential as an anesthetic product. Therefore, this study evaluates the anesthetic potential of Amyris balsamifera essential oil in Colossoma macropomum as a therapeutic window through behavioral tests and electrocardiographic recordings. The fish were exposed to Amyris balsamifera essential oil at concentrations of 20 μL L^-1, 25 μL L^-1, 30 μL L^-1, 35 μL L^-1,and 40 μL L^-1, in immersion baths. The behavioral test showed that can caused a loss of the postural reflex in fish, with a reversible effect and recovery times dependent on the concentration of oil used. In addition, this study showed that sandalwood essential oil has the potential to decrease heart rate and maintain sinus rhythm with a dose-dependent effect. These findings were made possible by behavioral analysis parameters and electrocardiographic recordings. These results demonstrate the existence of a safe therapeutic window for the use of Amyris balsamifera essential oil, since in the present study, there were superficial anesthetic planes with treatments of 20 and 25 µL L^-1, characterized by rapid recovery after contact and with little cardiorespiratory depression. And for deep anesthetic planes, treatments with 30 to 40 µL L^-1, with greater cardiorespiratory depression and longer latency for recovery.