On the efficacy and mode of action of 2‐phenoxyethanol as an anaesthetic for goldfish,Carassius auratus(L.), at different temperatures and concentrations

摘要

AbstractThe objective of this study was to assess the efficacy and mode of action of 2‐phenoxyethanol as an anaesthetic for two size classes of goldfish,Carassius auratus(L.), at three different temperatures. Goldfish (2.15 ± 0.05 g, and 9.19 ± 0.17 g) were exposed to 0.3, 0.4 and 0.5 ml 2‐phenoxyethanol l1at 20, 25, and 30oC. Time needed to induce anaesthesia was dependent on concentration and water temperature. At temperatures at and below 25oC, 0.4 ml l1was needed to induce total loss of equilibrium within less than 15 min. Above 25oC, 0.5 ml l1was required to induce anaesthesia. Recovery rate was independent of the length of anaesthesia, which indicates that the anaesthetic is taken up and lost via a concentration gradient at the gill membrane and skin/solution interface. Fish recovered within less than 10 min after they had been taken out of the anaesthetic solution. In a second experiment, goldfish responded to a repeated exposure to 2‐phenoxyethanol daily over a period of 14 days with increased tolerance, which indicates a habituation response to the anaesthetic. The use of 2‐phenoxyethanol as an anaesthetic both for short‐term anaesthesia and for anaesthesia under transport conditions i