Studies On Edwardsiellosis And Pathology Of Several Important Diseases In Cultured Turbot

Turbot, Scophthalmus maximus (L.) is a very important commercial species in Europe, from where it was introduced into China in 1992. With the success in artificial breeding from 1998, the commercial culture has spread rapidly along the coast of North China. Recently, yields have reached 20,000MT, valued at 200 million RMB. However, with the rapid development of the turbot culture in China, several diseases occurred and it was suggested that they resulted from high-intensive cultivation and improper management since 2001. So the study of diseases is very necessary for maintaining the sustainable and healthy development of turbot culture.The paper is divided into two parts: One is study on edwardsiellosis in turbot; The other is study on pathology of several other diseases in cultured turbot.Study on edwardsiellosis in turbot. A survey was conducted in three cases of edwardsiellosis in cultured turbot collected from three different farms located along the coast of Shandong Province. The disease was found in two forms: acute and chronic. Signs of the disease varied depending on the clinical form. In acute cases, lesions were often observed as several red cutaneous foci on the ventral side and fins base of affected turbot and then progressed to abscesses with hemorrhagic borders in the body surface; In more chronic cases, the disease exhibited itself as a typically black darkening of the posterior portion of turbot's body. At necropsy, we found that all the affected fish had enlarged kidneys protruding beyond their normal position. The present study revealed three main types of kidney lesions with varying degrees of pathological change. In type 1, kidney was slightly swollen with gray-white nodules of varying sizes on the surface. In type 2, kidney showed extensive 'pyoid' necrosis after it was slit, as the whole organ was swollen and grayish in colour. In type 3,...