Efficacy of extracts of Thai medicinal plants as an anesthetics on carp fish (Cyprinus carpio)

Abstract

Anesthetics are widely used in aquaculture to prevent stress during handling. Main objective of our research is to investigate the efficacy of Thai medicinal plants in carp fish (Cyprinus carpio). We focused on the plant extracts from the family of Piperaceae according to their tranquilizing and sedative potential (1, 2). Psidium guajava was also included due to the ability to induce CNS depression (3). The ethanolic extract of Piper betle and Psidium guajava caused were significantly able to induce surgical stage (stage 4) anesthesia in concentration dependent manner. Extracts of P. betle at concentrations of 0.1, 0.2, 0.3 and 0.4mg/ml were able to induce 76.67±3.66, 90.00±4.14, 95.00±5.77 and 97.50±2.89% of fish in to anesthesia state, respectively. P. guajava extracts caused 80.00±10.00, 86.67±15.28 and 100% of fish to loss pain reflex, at concentrations of 0.1, 0.2 and 0.3mg/ml, respectively. The extract of P. betle significantly induced a faster anesthesia at 0.1mg/ml when compared to P. guajava. The recovery time of P. guajava was longer than P. betle at the same concentration. The acute toxicity tests were performed during 20min incubation periods. At concentrations of 0.1, 0.2, 0.3 and 0.4mg/ml P. betle caused a 30.0±10.0, 47.50±9.57 and 75.00±5.77% mortality, respectively. The mortality rates of fish exposed to P. guajava were 20.0±10.0, 50.0±10.0, 83.33±5.77% at the concentrations of 0.1, 0.2 and 0.3mg/ml, respectively. These findings suggest that the extract from P. betle could be an effective anesthetic for his species.