Induction and recovery from anaesthesia in fry of European catfish (Silurus glanis L.) exposed to clove oil

V. Krasteva*, A. Zaikov
Institute of Fisheries and Aquaculture, 4003 Plovdiv, Bulgaria
(Manuscript received 20 June 2019; accepted for publication 11 August 2019)

Abstract. The purpose of the study is to establish the efficacy of different concentrations of clove oil and the time needed for induction and recovery from anesthesia of European catfish (Silurus glanis L.) fry. The experiment was carried out in laboratory conditions with 50 specimens with body weight 1.11±0.25g and body length 5.45±0.60cm. For the aim of this paper the following five concentrations of clove oil are used: 0.01 ml.l-1, 0.02 ml.l-1, 0.03 ml.l-1, 0.04 ml.l-1 and 0.05 ml.l-1. At the lowest concentration (0.01ml.l-1) the effect is sedative and the fry do not reach the phase of complete immobilization. The application of 0.02 ml.l-1 concentration of clove oil is not beneficial for practical usage, with only 30% of the fish reaching phase 4 of anesthesia. At the highest concentrations (0.04 ml.l-1 and 0.05 ml.l-1) all of the fry were anesthetized for a short time, but the process of recovery was not successful for all of the fry. All of the fry reach phase of anesthesia and recovery without loses at 0.03 ml.l-1. This concentration is advisable for anesthesia of European catfish fry during different manipulations.