DAO 60:247-252 (2004)  -  doi:10.3354/dao060247

Important disease conditions of newly cultured species in intensive freshwater farms in Greece: first incidence of nodavirus infection in Acipenser sp.

F. Athanassopoulou1,*, C. Billinis2, Th. Prapas3

1Laboratory of Ichthyology, Fish Diseases and Aquaculture, and 2Laboratory of Microbiology and Parasitology,Faculty of Veterinary Medicine, School of Health Sciences, University of Thessaly, Karditsa, Greece
3Centre of Veterinary Establishments of Athens, Institute of Infectious and Parasitic Diseases, Laboratory of Fish Diseases, 25 Neapoleos Street, Agia Paraskevi, 15310 Athens, Greece

ABSTRACT: We describe here the main pathological conditions of freshwater fish recently introduced for intensive rearing (open ponds and recirculating freshwater systems) in Greece. Sturgeon were susceptible to skeletal abnormalities of the spine (scoliosis and lordosis) of unknown aetiology. Horizontal transmission of nodavirus from infected sea bass to sturgeon was detected for the first time. This caused serious pathology and clinical signs, such as lethargy and imbalance, leading to secondary infections with Aeromonas hydrophila and Trichodina sp. and chronic, but steady, mortality. Sea bass were very susceptible to nodavirus infection, monogenean infections and gas bubble disease. Mullet reared under recirculated and open-flow conditions were very sensitive to Chilodonella sp. infection, whereas catfish were susceptible to infection with Ichthyophthirius sp. leading to secondary infections with A. hydrophila, Saprolegnia sp. and Myxobacteria spp. Tilapia were very susceptible to gas bubble disease and A. hydrophila. This bacterium was associated with management manipulations for all species and fully responsive to corrective hygiene methods.


KEY WORDS: Freshwater aquaculture · Acipenser sp. · Mugil sp. · Recirculating systems · Nodavirus


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