Detecting Yersinia ruckeri on the death of carp (Cyprinus carpio) farmed in southern Russia

Abstract

Abstract Yersinia ruckeri was first discharged from carp brood fishes (Cyprinus carpio) farmed in ponds in southern Russia. The death of fish was observed at a temperature of 15°C in March-April 2015. Ten fish with clinical signs of the disease were taken for research. Water samples were taken for hydrochemical analysis. The research results indicated a high level of permanganate index (2.4–2.8 MAC), nitrite nitrogen (1.5–2 MAC), nitrate nitrogen (1.4–1.5 MAC), and a low oxygen content in the bottom layers (2.0 mg/dm3). A parasitological study of fish revealed an invasion by monogenes (Dactylogyrus extensus) and mollusks (Unio pinctorum). As a result of bacteriological studies, 62 isolates were discharged, 30 from water and 32 from fish. The determination of bacteria was carried out according to morphological and enzymatic properties. The biochemical characteristics of the Yersinia ruckeri strains made it possible to classify them as serotype 1. All Yersinia ruckeri strains were sensitive to ciprofloxacin, tetracycline, chloramphenicol and resistant to furazolidone. MALDI TOF mass spectrometry and PCR were used for additional identification of bacteria. Serious pathological and histopathological changes in the fish tissues were not detected.