Eugenol and benzocaine as anesthetics for Lophiosilurus alexandri juvenile, a freshwater carnivorous catfish

This work evaluated the blood parameters of Lophiosilurus alexandri juveniles submitted to doses of 80, 160, 320, and 640 mg L−1 eugenol (n = 60, 171.59 ± 37.87 g) and 60, 120, 240, and 480 mg L−1 benzocaine (n = 60, 214.87 ± 75.83 g) were tested. For each anesthetic, there was a control group. Thus, anesthesia time and recovery of the analgesia condition were evaluated. Of the 12 animals from each treatment, six went through blood collection after sedation and the other six, 24 h after anesthesia. The survival index for the use of both anesthetics, after 24 h after anesthesia, was 100%. The induction times for eugenol and benzocaine presented an inversely proportional ratio, while the recovery time, a ratio directly proportional to the increase in anesthetic concentrations. Glucose was higher after sedating the animals, regardless of the concentrations tested. The hematocrit had lower values after 24 h after anesthesia at the doses of 320 and 640 mg L−1, while the total protein was not affected during the observations. With the use of benzocaine, glucose was higher at concentrations of 240 and 480 mg L−1. In relation to time, glucose was higher after anesthesia. Total protein had higher values in the doses of 240 and 480 mg L−1. The hematocrit was not affected in the experiment. Concentrations between 80 and 160 mg L−1 eugenol and between 60 and 120 mg L−1 benzocaine may be used in anesthetic procedures of L. alexandri juveniles.