Anaesthetic Efficiency of Cymbopogon citratus Essential Oil and Clove Oil on Macrobrachium rosenbergii.

Background and Objective: Studies on plant herbs as alternatives to chemical anaesthetics in fish species are numerous, but little is known on crustaceans. A study was conducted to investigate the efficacy of C. citratus Essential Oil (EO) on the induction and recovery of M. rosenbergii. Materials and Methods: The C. citratus EO was obtained by hydrodistillation and analyzed using GC-MS. The prawns were exposed to C. citratus EO and clove oil in 100-1000 and 200-1000 μL L1, respectively. Different stages of induction and recovery times were recorded. Results: In GC-MS, citral (78.47%) was detected as a major compound in C. citratus EO. Prawns reached loss equilibrium at 500-1000 μL L1 C. citratus EO within 15.55-6.52 min. Exposure of prawn to 500 μL L1 C. citratus EO resulted in a high survival rate (100-94%). In clove oil, all tested concentrations caused significant induction in M. rosenbergii within 20.61-6.47 min. Recovery time and survival rate were significantly decreased with the increase of EO concentrations. The regression model showed the induction time in both anaesthetic agents was dependent on the concentration (R2 = 0.86-0.96). The recovery time of C. citratus EO-exposed prawn was dependent on the concentrations (R2 = 0.59). Conclusion: The study shows the potentiality of C. citratus EO as a natural anaesthetic in M. rosenbergii, although not as efficient as clove oil.