Anesthesia Using Eugenol for Two Weight Classes of Piaractus mesopotamicus: Evaluation of Induction Time, Recovery Time, Behavioral Response and Serum Glucose

Abstract

Aims: The use of anesthetics in fish ensures that they can undergo common handling in fish farming without causing damage to production. The aim of the present study was to determine the induction and recovery times of Piaractus mesopotamicus submitted to eugenol anesthesia. Study Design: 100 P. mesopotamicus were used, divided into two weight classes (Class I weighing between 275 and 460 grams; and Class II weighing between 461 and 680 grams). Methodology: The fish (n=10) were submitted to eugenol anesthesia in five dosages (50.0; 75.0; 100.0; 125.0 and 150.0 mg L−1) and the induction times to anesthesia and recovery to normal activity, as well as fish behavior during this stage. Results: There were statistical differences (p = .05) between anesthesia and fish recovery. For fish belonging to class I, the best dose to apply is 50 mg L−1, while for class II, the recommended dose is 75 mg L−1. Glucose was higher (p = .05) in animals submitted to a dose of 75 mg L−1 compared to those stunned at 50 mgL−1, but there was no effect between the other doses as well as between weight classes. Conclusion: Larger fish are induced to deep anesthesia and return to normal behavior before smaller fish. Considering the induction times to anesthesia and total recovery, it is recommended to use a dose of 50 mg L−1 for class I and 75 mg L−1 for class II.