Luis Antonio Kioshi Aoki Inoue

Clove oil as anaesthetic for juveniles of matrinxã Brycon cephalus (Gunther, 1869)

Many chemicals have been used as anaesthetics in fish farms and fish biology laboratories to keep the fish immobilized during handling procedures and to prevent accidents and animal stress. In Brazil, tricaine methane sulfonate (MS 222), quinaldine sulfate, benzocaine, and phenoxyethanol are the most common fish anaesthetics used to prevent fish stress during handling, but many side effects such as body and gill irritations, corneal damage and general risks of intoxication have been reported. Clove oil is a natural product proposed as an alternative fish anaesthetic by many researchers and it has been used in many countries with great economic advantages and no apparent toxic properties. In this work, we assessed the suitability of clove oil to anaesthetize matrinxa. Sixty-three juveniles of matrinxa were exposed to seven anaesthetic batches of clove oil (pharmaceutical grade) namely 18, 20, 30, 40, 50, 60, and 70 mg/L. The times to reach total loss of equilibrium and to recover the upright position were measured. Clove oil concentration about 40 mg/L was enough to anaesthetize the fish in approximately one minute and the recovery time was independent in regard to anaesthetic concentration.

Effects of clove oil on the stress response of matrinxã (Brycon cephalus) subjected to transport

Fish transport is one of the most stressful procedures in aquaculture facilities. The present work evaluated the stress response of matrinxa to transportation procedures, and the use of clove oil as an alternative to reduce the stress response to transport in matrinxa (Brycon cephalus). Clove oil solutions were tested in concentrations of 0, 1, 5 and 10 mg/L during matrinxa transportation in plastic bags, supplied with water and oxygen as the usual field procedures in Brazil. Clove oil reduced some of the physiological stress responses (plasma cortisol, glucose and ions) that we measured. The high energetic cost to matrinxa cope with the transport stress was clear by the decrease of liver glycogen after transport. Our results suggest that clove oil (5 mg/l) can mitigate the stress response in matrinxa subjected to transport.

Respostas metabólicas da tilápia do Nilo ( Oreochromis niloticus ) submetida ao manuseio e ao anestésico eugenol - DOI: 10.4025/actascibiolsci.v28i3.401

O eugenol e o principal componente do oleo de cravo, sendo proposto como anestesico alternativo para peixes, pois aparentemente nao apresenta caracteristicas toxicas aos trabalhadores e ao meio ambiente. Ainda, o uso de anestesicos durante o manejo de peixes pode reduzir o estresse e riscos de acidentes pela movimentacao excessiva dos animais. Portanto, a anestesia em peixes pode evitar mortalidade durante o manejo. Entretanto, ainda sao necessarios estudos sobre os efeitos do eugenol em peixes, o que pode assegurar a sua viabilidade de uso. O presente trabalho avaliou as respostas bioquimicas da tilapia do Nilo submetida ao manuseio e a duas concentracoes de eugenol. Os resultados indicam esse produto como seguro para uso nessa especie.

Standardization of 2-phenoxyethanol as anesthetic for juvenile Brycon cephalus (Gunther, 1869): the use in field procedures

Hyper motility is a negative factor in fish handling procedures due to the risks of damages to the animals. Chemicals are widely used to anesthetize fish during biometry and many other handling procedures. 2-Phenoxyethanol is largely employed, but many studies are necessary about tropical fish responses. The present research evaluated the anesthesia induction time for juvenile matrinxa submitted to eight different levels of 2-phenoxyethanol. The range of 2-phenoxyethanol concentration was 250-600mg liter-1. Induction time of anesthesia decreased as a function of 2-phenoxyethanol concentrations. Fish were safely anesthetized approximately after one minute of exposure to 2-phenoxyethanol batches in concentrations above 400mg/liter, and the recover period was about one minute for all anesthetic concentrations. 2-Phenoxyethanol is a safe anesthetic for juvenile matrinxa even in exposures up to 600mg liter-1 being recommended for many field procedures of fish handling.