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

R.M Viegas,T.C Santana,C.L França,E.G Teixeira,R.N.F Carvalho Neta,M.P.G Costa-Lima,J.J.P Castro,C.R.P Carreiro,J.S Castro

doi:10.1590/1678-4162-11866

Abstract

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.

Highlights

Routine procedures of aquaculture activity such as biometrics, hormonal applications, and transport have strong effects on physiology and can cause high levels of stress in fish, increasing susceptibility to pathogenic and infectious diseases, affecting their reproductive capacity and even death (Hurst, 2007)
The specimens of P. nigricans isolated from different anesthetics of eugenol have indicative sizes of adult fish, including average amplitude data of the first sexual maturation of species recorded by Mota and Rufino (1997)
The use of anesthetic is essential during management procedures, for the ideal use of this anesthetic, it is necessary to understand the dose required for a given size of fish, since different size fish respond differently to the anesthesia time when submitted to the same anesthetic concentrations (Roubach et al, 2005), in addition, the ideal use of the anesthetic avoids mortality and minimizes management costs

Summary

Introduction

Routine procedures of aquaculture activity such as biometrics, hormonal applications, and transport have strong effects on physiology and can cause high levels of stress in fish, increasing susceptibility to pathogenic and infectious diseases, affecting their reproductive capacity and even death (Hurst, 2007). The appropriate anesthetic at its optimal concentration should minimize negative impacts of management, reduce stress on fish, produce anesthesia less than or equal to three minutes, and recovery should occur within 5 to 10min (Marking and Meyer, 1985; Ross and Ross, 2008). These characteristics include eugenol (4-allyl-2methoxyphenol), a compound derived from clove oil, viscous liquid obtained by distillation of the leaves, buds, flowers and stem of Eugenia aromatica or Eugenia caryophyllata (Mylonas et al, 2005). Eugenol has been found to be an acceptable anesthetic with potential for use in aquaculture and has been widely used in several studies with different fish species (Moreira, 2009; Rotili et al, 2012), but studies to verify likely immediate effects on fish structures such as gills are incipient

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