EN
This report presents the data considered by the author as the most important reasons for difficulties in the diagnosis and control of MAS and MAI caused by motile Aeromonas bacteria in fish. The difficulties are chiefly attributed to the properties of these microorganisms, such as their wide variety and variability. Furthermore, numerous studies into certain aspects involved in the pathogenecity of motile Aeromonas in fish have been indicated; however, the comparison of the results of these studies is limited or impossible. The necessity of investigations which may improve diagnostic procedures as well as lead to more applicable, efficient and reasonable methods of the control of MAS and MAI has been stressed.