CONTROL OF AEROMONAS SALMONICIDA INFECTION IN RAINBOW TROUT (ONCORHYNCHUS MYKISS) REARED IN RECIRCULATING AQUACULTURE SYSTEM

Angelica Docan, V. Cristea, Lorena Dediu, Aurelia Nica

Abstract
Recirculating systems create unique environments for fish culture which may provide favorable conditions for disease occurrence or the reproduction of opportunistic microorganisms. Stressful conditions in recirculating systems, such as poor water quality or high stocking densities in the culture tanks, may contribute to disease outbreaks. The present study was conducted in the context of pathogen bacteria proliferation reported in the case of Onchorhynchus mykiss reared in a recirculating system. First clinical signs of disease were evident in terms of lesion: bleeding ulcers on the skin surface, bruising at the base of fins, bleeding oral region. A. salmonicida has been isolated from the kidneys, blood and furuncle of sick fish. Furunculosis is a bacterial infection of salmonids and other fishes caused by Aeromonas salmonicida. Aeromonas salmonicida strains isolated from diseased specimens of trout, showed an antibiotic resistance-type "multi-Steep" being sensitive to chloramphenicol, kanamycin, streptomycin and resistant to penicillin, ampicillin, tetracycline, oxacillin and erythromycin. Following application of different treatment schemes, the best results were obtained with chloramphenicol for 7 days.

Key words: Oncorhynchus mykiss, Aeromonas salmonicida, recirculating aquaculture system