Env Exp Biol (2010) 8: 103–106

The prevalent bacterial fish diseases in fish hatcheries of Latvia

Abstract

To evaluate the bacterial background, pathological examination of fish was performed in seven state fish hatcheries and three private farms from 1997 to 2009. A total of 3334 individual fish were examined. Bacteriological material from ulcers of the surface, gills, heart, liver, kidney, spleen and muscles was collected from individuals with visible clinical signs and from clinically healthy fish. Bacteriological samples were inoculated on plates with specific medium. Representative colonies were cultivated for further biochemical characterization and identification. Strains were identified by using commercial bacterial identification test strips. The study showed that the prevalent isolated pathogenic bacteria were Flexibacter spp., Aeromonas salmonicida, and Aeromonas hydrophila. Bacteriological examination revealed that 15.3% of tests were positive for aeromonosis,16.5% tests for myxobacteriosis and 68.2% tests demonstrated negative results. Greater attention should be directed to fish bacterial diseases, as they have a significant impact on cultured and occasionally wild populations.