Iridovirus-like infection associated with high mortalities of striped beakperch, Oplegnathus fasciatus (Temminck et Schlegel), in southern coastal areas of the Korean peninsula

High mortalities of net-caged striped beakperch (Japanese parrotfish), Oplegnathus fasciatus (Temminck et Schlegel), in southern coastal areas of the Korean peninsula occurred from August to early September, 1998. During epizootics, the water temperature was 23-27 degree C with salinity of 29-33%. The disease occurred in all age groups, including 3-yr-old market-sized striped beakperch, with consequent severe economic losses. Estimated mortality of the striped beakperch in these areas was about 60% of total fish numbers (3 million). Similar clinical signs were also seen in red sea bream, Pagrus major (Temminck et Schlegel), in the same area. However, the mortality of red sea bream was less than 5%. From August to early September, 1998, 111 striped beakperch and 37 red sea bream were collected from four fish farms in Tongyoung, two fish farms in Yosu, and one fish farm in the Koje area, where severe mortalities were recorded. The initial signs of the disease were reduced feed intake, lethargy and a darkened body, with atypical swimming at the edge of cages in the terminal stages of the disease. Moribund and dead fish were transported to the laboratory fresh on ice or in a plastic bag with aeration. The examined fish were anaemic, showed gill petechiae, congestion of the liver and enlargement of the spleen and kidney.