ABSTRACT
The aim of this study was to evaluate the effectiveness, at different concentrations, of the natural anaesthetic, eugenol, during the anaesthesia of farmed lane snapper (Lutjanus synagris). One hundred and eight individuals were used, classified into three classes by size: fry (n = 36), juvenile (n = 36), and adult (n = 36), having an average weight of 3.58 ± 0.63 g, 20.24 ± 5.53 g and 263.51 ± 52.20 g respectively. The concentrations tested for the three classes were 25, 50 and 75 mg L-1, with times for anaesthesia and recovery being recorded on a digital timer. The results showed that for the three classes of size, the higher the concentration of eugenol used, the less the time taken to reach each stage of anaesthesia. The total time for induction of anaesthesia was less than three minutes; the best concentration being 50 mg L-1 for all the classes under test. Recovery time at this concentration of the anaesthetic was 120.7 ± 36.3 s, 78.95 ± 16.52 s, 103.33 ± 22.09 s, for the classes of fry, juveniles and adults respectively. The use of eugenol as an anaesthetic in L. synagris was considered to be effective within recommended standards, with the ideal concentration not varying by class.
Key words:
Marine fish farming; Anaesthesia; Lutjanidae; Clove oil
