The efficacy of clove oil as an anaesthetic and in euthanasia procedure for small-sized tropical fishes

Abstract

Clove oil is used as a fish anesthetic because it is a natural and inexpensive product with low toxicity risks. The goal of the present study was to determine the appropriate concentration of clove oil for small-sized tropical fish to be used in mark-recapture studies or when individuals are to be sacrificed. We applied three different clove oil concentrations (D1=0.05 mL, D2=0.10 mL and D3=0.20 mL per 500 mL of water) on three small-sized fish species. We found a negative relationship between induction time and treatment for two species (Hyphessobrycon sp.1 and Hemigrammus sp.), while concentration was unrelated to recovery time. Fish body length was positively related to induction time in the D2 treatment for Hemigrammus sp., and negatively for Hyphessobrycon sp.1 in the D1 treatment, but was unrelated to recovery time for three species and treatments. Mortality rates varied across treatments, but higher rates were observed with higher clove oil concentrations. We conclude that 0.05 mL of clove oil per 500 mL of water is the most efficient dose for studies where fish will be released back to their natural habitats, while 0.20 mL of clove oil is recommended for studies that require fish euthanization for further laboratory analyses.Keywords: Eugenol, anesthesia, euthanasia, field experiment, fish manipulation.A eficiência do óleo de cravo como anestésico e em procedimentos de eutanaisa em peixes de pequeno porte Resumo O óleo de cravo é recomendado como anestésico para peixes por ser produto de origem natural, baixo custo e apresentar poucos riscos de intoxicação. O objetivo deste trabalho foi determinar concentrações adequadas de óleo de cravo para anestesiar ou eutanasiar peixes de pequeno porte em ambiente natural. Foram testadas três concentrações do anestésico (D1=0,05 mL, D2=0,10 mL e D3=0,20 mL) em três espécies de peixes de pequeno. Houve uma relação negativa entre o tempo para a sedação dos indivíduos e a concentração para duas espécies (Hyphessobrycon sp.1 e Hemigrammus sp.), porém não foi encontrada relação entre o tempo para recuperação e as concentrações. Os exemplares maiores de Hemigrammus sp. levaram mais tempo para serem sedados no tratamento D2, já o contrário foi observado para Hyphessobrycon sp.1 no tratamento D1, enquanto que não houve efeito do comprimento no tempo de recuperação das três espécies. A mortalidade dos indivíduos variou entre as três concentrações do anestésico e as maiores taxas de mortalidade ocorreram nas maiores concentrações. Desse modo, a concentração de 0,05 mL é eficiente para estudos que envolvem manuseio e a soltura dos peixes, enquanto que a concentração de 0,20 mL é recomendada em estudos onde os peixes precisam ser sacrificados.Palavras-chave: Eugenol, anestesia, eutanásia, experimento de campo, manipulação de peixes.

Myrcia sylvatica essential oil in the diet of gilthead sea bream (Sparus aurata L.) attenuates the stress response induced by high stocking density

“…In the current study, the cortisol levels in the control group presented the same range of variations than those measured in Experiment I. These results further confirm the ability of EOMS to reduce the activity of the HPI axis and modulate the activation of the hormonal cascade associated with the stress response (Iversen et al, 2003;Small, 2003;Wendelaar-Bonga, 1997). Even so, in chronic stress experiments, no evidences of a marked variation of cortisol values were observed in the control group, although a plausible effect between diet supplementation and stocking density was observed.…”

“…Cortisol is involved in several physiological processes, such as the regulation of metabolic pathways, behaviour, growth, reproduction and osmoregulation (Mommsen, Vijayan, & Moon, 1999 (Gressler et al, 2014;Iversen, Finstad, McKinley, & Eliassen, 2003;Saccol, Londero et al, 2017;Saccol, Toni et al, 2017). However, the exact mechanism underlying the effect of EOs on cortisol secretion remains unknown.…”

“…Moreover, in fish fed with EOMS-supplemented diet, a lowering effect in lactate levels was observed when compared to control fish, possibly due to a mitigation of the stress response caused by higher stocking densities, and also by a downregulation of the proposed aspect of the energetic metabolism. Furthermore, some studies demonstrated the lack of a direct relationship between primary and secondary responses (Iversen et al, 2003;Park et al, 2008), in the storage of hepatic glycogen after increased stocking conditions. Even so, the unique variation in hepatic glucose was observed in fish fed the diet containing 1.0 ml EOMS and held at HD, suggesting that EOMS does not have a clear influence on the hepatic metabolism of carbohydrates under our experimental conditions, and further studies will be necessary to understand this intriguing response.…”

Stream Fish in the Aripuanã River Upstream and Downstream of the Dardanelos-Andorinhas Waterfall Complex, State of Mato Grosso, Brazil

“…After blocking each stretch, specimens were collected using hand gathering techniques with a sieve (0.8 × 0.7 m, 2.5 mm mesh) and a hand net (2.0 × 1.0 m, 5 mm mesh) for 4-person hours per stretch ( Figure 3) (to more information about the method see Mendonça et al 2005). Captured fish were euthanized by anesthetic overdose (0.2 ml oil clove/500 ml water, Fernandes et al 2017).…”

Transcriptome analysis reveals the influence of anaesthetic stress on the immune system of crucian carp ( Carassius auratus ) under the process of treatment and low concentration transport by MS‐222 and Eugenol

“…Corresponding stress responses are formed, which include changes in energy metabolism, plasma hormones and electrolyte balance, eventually causing vast economical loss and affecting research reliability (Ross & Ross, 1999;Wendelaar Bonga, 1997). Therefore, to reduce the stress associated with the procedures of harvesting, sampling and spawning, anaesthetics are widely used in aquaculture and research (Coyle, Durborow, & Tidwell, 2004;Fernandes, Bastos, Barreto, Lourenco, & Penha, 2017). Similarly, to alleviate the stress generated by fish during transportation, low concentration of anaesthetics is widely used to reduce the metabolic rate and oxygen demand, as well as maintain the fish in a state of deep sedation while maintaining equilibrium (Benovit et al, 2012;Cook, Suski, Ostrand, Tufts, & Wahl, 2004).…”