Yersiniosis is a septic disease infecting salmonides, especially trout (Salmo irideus), and is registered in the Baltic region, in most East and West European countries, and in the U.S.A. Pathogen is distinguished also in cisco (Coregonus), white perch (Eupharyngidae), sturgeon, spinedace, perch and crawfish. The document consists of 4 Secs. Section 1 lays down general provisions. Section 2 regards epizootology. Section 3 regards clinical symptoms and pathologo-anatomical changes. Section 4 rega