Screening of pathogenic bacteria and SVCV (Spring viremia of carp virus) in propagated Cyprinidae spp and Sander lucioperca in Poldasht Shahid Kazemi warm water fish caltured center of West Azarbaijan - Iran

Annually, More than 6 millions of cyprinid fish including Silver Carp( Hypophthalmichthys molotrix ) , Big head (Hypophthalmichthys nobilis ) , Grass carp( Ctenopharyngodon idella ) , Common carp( Cyprinus carpio)and Pike perch ( Stizostedion lucioperca) are produced in Poldasht Shahid Kazemi Propagation Center and released to water resources of West Azarbaijan to restocking purposes. Also, a large number of these fish are transported to the water sources and fish farms of the other parts of the country. Septicemia caused by motile Aeromonas species is considered as the famous disease in freshwater fish. It considered to cause of heavy losses in cyprinid farms of Iran in spring and summer, in recent years. On the other hand, Spring Viremia of Carp is considered as a sever pathogen of cyprinid fish in different parts of the world and has listed as notifiable diseases by OIE. This study was carried out to isolate and identify motile Aeromonas bacteria and SVCV in propagated cyprinid and lucioperca fish of Poldasht Shahid Kazemi Propagation Center. For this purpose, 40 fish of each species (totally 600 specimens), respectively with average weights of 500± 0.3 mg in incubation hall and 10±1 g in earthen ponds were sampled to determine bacterial infection. Samples from kidney, spleen, liver, blood, skin and gills were taken and cultured on BA, TSA, BHIA and NA and biochemical and differential tests were done. The bacteriological results represented the lowest percent of contamination with A.hydrophila in kidney and liver (1.5 ± 0.2%) at incubation stage and the highest (75.9±0.12%) during transferring to water resources. Also, Bacterial agents including Aeromonas sobria, Escherichia coli, Micrococcus,Staphylococcus, Aeromonas sp., Proteus mirabilis, P.aeruginosa, P.fluorescens and Pseudomonas putida were isolated and identified from sampled tissues. To isolate SVC virus with prevalence rate of 2%, 150 samples from 5 mentioned species were taken from kidney, spleen, gill and brain tissues (fish with 10±1 g weight and one year old fish) before transferring to the water resources. All samples were tested using RT-PCR for virological tests. The results showed the probability of SVC virus in one year old big head. Confirmation of the virus in accordance with international guidelines and the OIE requires additional testing and cell culture, the coordination of these tests with the National Veterinary Organization(IVOC) was carried out, which confirmed the failure to verify the results of definitive diagnostic tests .Finally The virus was not approved by the IVOC.

Iranian Fisheries Science Research Institute

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