The efficacy of three common fish anesthetics (clove oil, 2-phenoxyethanol, and tricaine methanesulfonate) was evaluated in the Pacific hagfish (Eptatretus stoutii). The overarching aim of our study was to identify the best anesthetic and concentration for the purposes of routine laboratory use of Pacific hagfish (i.e., short and consistent induction and recovery times and minimized stress and safety risk to hagfish). The objectives of our study were fourfold: (1) identify anesthetic stages of Pacific hagfish using clove oil anesthesia; (2) establish standardized anesthesia preparation procedures; (3) determine the optimal anesthetic and concentration for safely achieving stage V anesthesia; and (4) investigate the effects of repeatedly exposing Pacific hagfish to anesthesia. Experimental concentrations, ranging from 50 to 400 mg/L, of each anesthetic were tested on at least three Pacific hagfish individuals. We found the following: (1) Pacific hagfish exhibited similar stages of anesthesia to those described for bony fishes; (2) sufficient mixing of clove oil with seawater had a considerable effect on the consistency and timing of anesthetic induction; (3) concentration and anesthetic significantly impacted induction and recovery timing, whereas body mass had no impact on anesthetic trends; and (4) repeatedly exposing Pacific hagfish to optimal concentrations of clove oil or MS-222 had no effect on induction or recovery timing, whereas exposure number significantly impacted induction timing when using 2-PE. Due to consistent induction and recovery times, low risk of accidental overdose, and high safety margins for both handler and hagfish, we recommend 175 mg/L of clove oil as the ideal anesthetic and concentration for the routine laboratory use of Pacific hagfish.

中文翻译：

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三种常见的鱼麻醉剂对太平洋g鱼（Eptatretus stoutii）的浓缩作用。

在太平洋ha鱼（Eptatretus stoutii）中评估了三种常见的鱼麻醉剂（丁香油，2-苯氧基乙醇和三卡因甲磺酸盐）的功效。我们研究的总体目标是为常规实验室使用太平洋ha鱼确定最佳的麻醉剂和浓度（即短而一致的诱导和恢复时间，并最大程度降低对ha鱼的压力和安全风险）。我们的研究目标有四个方面：（1）使用丁香油麻醉确定太平洋ha鱼的麻醉阶段；（2）建立规范的麻醉准备程序；（3）确定安全地达到V期麻醉的最佳麻醉剂和浓度；（4）研究反复使太平洋g鱼麻醉的效果。实验浓度范围为50至400 mg / L，每种麻醉剂中的至少一种在至少三只太平洋Pacific鱼身上进行了测试。我们发现以下情况：（1）太平洋ha鱼的麻醉阶段与针对骨鱼的麻醉阶段相似；（2）丁香油与海水充分混合，对麻醉诱导的稠度和时间有很大影响；（3）浓度和麻醉剂显着影响诱导和恢复时间，而体重对麻醉剂趋势没有影响；（4）将太平洋Pacific鱼反复暴露于丁香油或MS-222的最佳浓度，对诱导或恢复时间没有影响，而使用2-PE时，暴露次数会显着影响诱导时间。由于持续的诱导和恢复时间，意外用药过量的低风险以及处理人员和混养鱼的安全系数高，