Eugenol as an efficient anesthetic for neotropical fish Prochilodus nigricans (Teleostei, Prochilodontidae)

ABSTRACT The use of anesthetics in fish farming is essential to reduce stress during management. The present study proposes to evaluate the effect of eugenol as an anesthetic for the management of curimatã (Prochilodus nigricans). Fifty specimens were used (221.34±9.0 g; 25.8 ±1.1 cm), submitted to five treatments with concentrations of 0, 25, 50, 100 and 200 mgL−1 eugenol for 10 min. The times required to reach each anesthetic stage and the recovery of each fish were recorded. To check bloodglucose levels individual blood samples were taken from the fish before immersion and after ten minutes of anesthetic exposure. Evaluation of the anesthetic effect ongills was performed by histopathological analysis. The concentration of 50 mgL−1 was within the ideal limit of three minutes recommended for surgical anesthesia induction and did not significantly increase glucose levels when compared to the control group (35.7±19.4 mg dL−1), besides not causing gill injuries. At this concentration the fish presented controlled blood glucose levels within the basal levels, besides not taking the risk to have later problems concernig mortality, because this concentration ensures the good health of the gills and good recovery of the animals.

摘要：水产养殖中施用麻醉剂，对于降低养殖管理过程中鱼体的应激反应至关重要。本研究旨在评估丁子香酚（eugenol）作为麻醉剂，应用于巴西无齿脂鲤（*Prochilodus nigricans*，俗称curimatã）养殖管理的效果。实验共使用50尾试验鱼（体重221.34±9.0 g，体长25.8±1.1 cm），设置0、25、50、100、200 mg·L⁻¹共5个丁子香酚浓度处理组，麻醉处理时长为10分钟。记录每尾鱼抵达各麻醉阶段的用时以及苏醒恢复的时间。为检测鱼体血糖水平，分别于麻醉液浸泡前及麻醉暴露10分钟后采集每尾鱼的血液样本。通过组织病理学分析，评估麻醉剂对鱼鳃的作用效果。结果显示，50 mg·L⁻¹浓度组的麻醉诱导时长符合外科手术麻醉推荐的3分钟理想阈值，与对照组（血糖值35.7±19.4 mg·dL⁻¹）相比，该组鱼体血糖水平未出现显著升高，且未造成鱼鳃损伤。该浓度下，鱼体血糖水平维持在基础生理区间内，不会带来后续死亡相关风险，因为此浓度可保障鱼鳃健康以及试验鱼的顺利苏醒恢复。