Influence of the method of preparation of clove oil emulsion on the anaesthetic effect in fish (on the example of Clarias gariepinus

Abstract

In aquaculture, the use of clove oil as a natural anaesthetic for hydrobiontes is gaining popularity. There are several ways to prepare an aqueous emulsion for anaesthesia, which creates a problem for technologists in choosing the most effective one. The purpose of the study was to compare the anaesthetic effect of clove oil in three methods of preparation of the mixture on the youth of the African clary catfish. The study was conducted at the Centre for Aquatic Bioresources and Aquaculture of the National University of Life and Environmental Sciences of Ukraine. Research methods – Ichthyological and statistical. The activity of a water-based clove oil preparation was evaluated using three methods: hot, cold, and alcohol. Experimental material – juvenile fish of the clary catfish with an individual body weight from 22 to 285 g. Experimental conditions: the experimental material was kept without feeding for a day before the start of the study; fish anaesthesia was performed in the water at the temperature of +26 0C; the duration of manipulations with each fish was minimal. The effectiveness of various methods of preparation of the emulsion was evaluated by the duration of fish entry into the state of anaesthesia and withdrawal from this state. The advantage of the hot method of preparing an aqueous emulsion of clove oil over the other two is established: the duration of fish entry into anaesthesia was 22% shorter compared with the cold method, and 12.3% – with the alcohol method (p ≤ 0.05). The duration of fish recovery from anaesthesia with the hot method of preparation of the mixture was also shorter: compared to the cold method – 18% (p ≤ 0.05), with the alcohol method – 43.2% (p ≤ 0.001). Using correlation analysis, a relationship was established between the duration of fish entry into the state of anaesthesia and the individual body weight of the fish. Degree of binding: high for hot (r = 0.606) and alcohol methods (r = 0.529) and medium for a cold method of preparation of an anaesthetic mixture (r = 0.385). The results obtained are of practical value for improving the method of anaesthesia of fish using clove oil