Anesthetic effects of AQUI-S 20E® (eugenol) on the afferent neural activity of the oyster toadfish (Opsanus tau)

Rosalyn L Putland, Loranzie Rogers, Beth Giuffrida, Allen Mensinger

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Anesthesia is used to sedate aquatic animals during transportation or to immobilize them for surgery. However, most studies have focused on the behavioral effects of induction and recovery, without addressing the effect of anesthetic on neural activity. This study investigated the neural response of anterior lateral line afferent fibers in the oyster toadfish, Opsanus tau, during exposure to incremental increases of AQUI-S 20E (0.001–0.006%), to determine if eugenol (the active ingredient of AQUI-S 20E) influences neural activity of the fish lateral line system. Ventilation rate significantly decreased following AQUI-S 20E exposure with the surgical plane of anesthesia reached at 0.003%, characterized by shallow ventilation, equilibrium loss, and no response to tactile stimuli. Spontaneous and evoked firing rates of anterior lateral line fibers also significantly decreased following exposure, although the effect was transitory as neural activity recovered in the majority of fibers (70%) within 30 min of anesthetic withdrawal. While AQUI-S 20E proved effective in inducing the surgical plane of anesthesia without compromising survival, it is not recommended for acute neural preparations due to its depression of neural activity. However, the depression of lateral line sensitivity at low concentrations could play a role in reducing the stress response during fish transport.

Original languageEnglish (US)
Pages (from-to)2213-2226
Number of pages14
JournalFish Physiology and Biochemistry
Issue number6
StatePublished - Dec 1 2020

Bibliographical note

Funding Information:
The authors would like to acknowledge the Marine Resources Center staff at the Marine Biological Laboratory for providing toadfish care. We would also like to thank Lisa Abbo for veterinary advice on the project, and the Aquatic Animal Drug Approval Partnership Program (AADAP) and Bonnie Johnson at the (INAD) for overseeing animal care protocols when using AQUI-S 20E. The project was conducted under study #11-741-19-256.

Funding Information:
Funding was provided by the Mistletoe Postdoctoral Fellowship to RLP, the National Science Foundation Graduate Research Fellowship Program under grant DGE 1762114 to LSR, and the National Science Foundation Grant IOS 1354745 to AFM. Acknowledgments

Publisher Copyright:
© 2020, Springer Nature B.V.


  • Anesthesia
  • Eugenol
  • Fish
  • Neural activity
  • Ventilation rate

PubMed: MeSH publication types

  • Clinical Trial, Veterinary
  • Journal Article


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