Objective: To verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish.
Study design: Clinical study, randomized, parallel, multi-arm with control group in target species.
Animals: A total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used.
Methods: Silver catfish and grass carp were exposed to different concentrations of citral, 15-675 and 15-600 μL L-1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 μL L-1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 μL L-1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment.
Results: Citral only induced sedation from 15, 25 and 40 μLL-1 in both species. Anesthesia without mortality was induced in silver catfish at 50-600 μL L-1 and grass carp at 75-450 μL L-1. At 675 and 600 μL L-1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments.
Conclusions and clinical relevance: Citral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.
Keywords: Aloysia triphylla; fish; grass carp; hematology; silver catfish; veterinary drug.
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