Wafaa Ahmed Al Rawahi Keeping pastime and aquaculture industry of live freshwater fish are the main vectors for international trade of live fish. The transboundy movement of live fishes has been found to be associated with introduction of exotic parasitic and infectious viral agents. Worldwide a variety of parasites have been introduced through ornamental fish trade including various genera of monogenea, digenea, protozoa and metazoa. Viral agents have also been transmitted particularly in the latent stage of infection. Few studies have been conducted in the world regarding the parasitic and viral infections associated with ornamental fish trade and none conducted in Oman. Therefore, the goal of this study was to assess the biosecurity risks, parasitic and viral agents associated with importation of ornamental fish into Oman. A survey was carried out to investigate the prevalence of gill ectoparasites and infectious viral agents of imported ornamental fishes. A sample of 81 imported goldfish were sampled from three pet shops (Al Hail, SABCO and Al araimi) in Muscat governorate and examined for ectoparasite infestation. The prevalence of ectoparasites from imported goldfish was compared with the prevalence of ectoparasite of examined Omani native freshwater fish (n=113) sampled from Wadi Daqeq in Sharqiyah Governorate. A group of imported ornamental fish species (n=136) that originally imported from Thailand, Singapore and Taiwan were sampled for virological examination. Ornamental fish species including Goldfish, Koi carp, Catfish, Pacu, Tiger barb, Sucker fish, Oscar, Golden gourami, Blue gourami and Silver carp were selected. Pooled samples of spleen, kidney and liver were tested for the presence of Koi Herpesvirus (KHV) and Iridovirus (IV) by following OIE PCR protocols. The results obtained revealed overall ectoparasitic infestation of 97.53% in goldfish and 51.31% in Omani native freshwater fishes. It showed high prevalence of three genera of ectoparasite namely Dactylogyrus sp. (83.95%), digenean metacercaria (58.02%) and Tricodina sp. (11.11%) in the sampled goldfish. The former two parasitic genera were also prevalent with other monogenean Gyrodactylus sp. in native freshwater fish as (31.86%), (36.28%) and (7.08%) respectively. Based on the PCR test, 2 out of 25 pooled sample groups were positive for the presence of KHV. Sequence analysis of representative PCR products showed 100% genetic homology with the complete genome of cyprinid herpesvirus strain KHV-GZ11 (gi/647842001/KJ627438.1). The virus was detected in asymptomatic goldfish from Al araimi and Al Hail pet shops, originally imported from Thailand. The broad host range and pathogenicity of KHV highlights an emerging biosecurity risk. Moreover, new regulations on the importation of live aquatic animals should be studied and established including assessment of health certificate, establishment of quarantine practice and inspection of ornamental fish's consignments. Key words: biosecurity risk, imported ornamental fish, prevalence, parasite, virus.