Peppermint essential oil as an anesthetic for and toxicity to juvenile silver catfish

Diogo Bessa Neves Spanghero,Emília Carolina Alencar De Medeiros Spanghero,Francisco Célio Maia Chaves,Edsandra Campos Chagas,Janaína Dos Santos Pedron,Evoy Zaniboni-Filho

doi:10.1590/s1678-3921.pab2019.v54.00367

Abstract

Abstract: The objective of this work was to evaluate peppermint (Mentha piperita) essential oil toxicity to and potential as an anesthetic for juvenile silver catfish (Rhamdia quelen). To determine the lethal concentration at 4 hours (LC50-4h), 210 fish (3.08±0.8 g and 7.59±0.67 cm) were exposed to 0, 20, 50, 80, 110, and 140 mg L-1 essential oil. To evaluate the anesthetic potential, nine fish were individually exposed to each oil concentration (50, 80, 110, and 140 mg L-1) used. Water quality parameters were controlled. The mortality rate and the severity and extent of the gill injuries of silver catfish juveniles at 4 hours of exposure increased with increasing peppermint essential oil concentrations, with LC50-4h estimated to be 75.06 mg L-1. The main gill injuries were: congestion of the venous sinus of the primary lamella and at the base of the secondary lamella; interlamellar hyperplasia with fusion of lamellae; epithelial detachment; dilation of the venous sinus; edema adjacent to the lamella; and aneurysm. However, this oil is an effective anesthetic for silver catfish juveniles at the concentration of 80 mg L-1, with a short time of anesthesia (<4 min) and recovery (<10 min), with no mortality.

Highlights

There are few safe, effective, and practical sedative options available for fish (Trushenski et al, 2013)
Benzocaine can induce methemoglobinemia, which can interfere with oxygen transport through the blood, and MS-222, effective, is limited by regulatory agencies such as the US Food and Drug Administration (FDA), which prohibits the consumption of treated fish for a period of 21 days (Trushenski et al, 2013)
In the acute toxicity test, no mortality was observed in the control groups or in the treatment with the lowest essential oil concentration (20 mg L-1) after 4 hours of exposure

Summary

Introduction

There are few safe, effective, and practical sedative options available for fish (Trushenski et al, 2013). Benzocaine can induce methemoglobinemia, which can interfere with oxygen transport through the blood, and MS-222, effective, is limited by regulatory agencies such as the US Food and Drug Administration (FDA), which prohibits the consumption of treated fish for a period of 21 days (Trushenski et al, 2013). The effects of prolonged MS-222 exposure include hypoxia (inadequate oxygen supply at the tissue or whole-body level), increased plasma lactate concentrations, hyperglycemia (elevated blood glucose levels), increased urinary output, and electrolyte loss. It can be continuously absorbed throughout immersion, leading to a lethal overdose (Treves-Brown, 2000). The FDA’s Center for Veterinary Medicine (CVM) does not recommend the use of clove oil or of any of its components in fish (United States, 2007) because of its carcinogenic potential in rats (NTP, 1983)

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