Effects of clove oil anaesthesia on common carp (Cyprinus carpio L.)

The aim of the study was to investigate acute toxicity of clove oil for common carp and, using values of haematological and biochemical profiles of blood and histological tissue examinations, to assess the effects of the fish exposure to that anaesthetic. Acute toxicity values of clove oil for carp were found 10 minLC50 74.3 mg/l; 10minLC0.1 51.6 mg/l; 10minLC99.9 110.1 mg/l; 96hLC50 18.10 mg/l; 96hLC0.1 15.45 mg/l; and 96hLC99.9 19.80 mg/l. The fish were divided into four groups for haematological and biochemical examinations of blood and histological examinations of tissues. The groups were Control I (before the anaesthetic administration), Experiment I (immediately after 10 min anaesthesia at the concentration of 30 mg/l), Experiment II (24 hrs after 10 min anaesthesia) and Control II (controls examined in parallel with Experiment II). A total of 40 carp were examined. Clove oil anaesthesia had not effect on the haematological profile. The 10-min exposure to clove oil at a concentration of 30 mg/l caused a significant (P < 0.01) increase in the concentration of glucose (GLU) and inorganic phosphate (PHOS) immediately after anaesthesia. Clove oil anaesthesia had not effect on other biochemical indices. Histological examination showed capillary ectasia of gill filaments immediately after clove oil anaesthesia. Twenty-four hours after anaesthesia, no ectasia was observed. No histopathological changes were demonstrated in other tissues following anaesthesia. Results of the examinations suggest that the use of clove oil at a concentration of 30 mg/l does not cause irreversible damage in carp.