The Rosette Agent spreads rapidly through the healthy carrier species topmouth gudgeon, which has incredible invasive potential, originating from South East China, but spreading to other parts of Asia, Europe and North Africa with alarming implications The rosette agent is the suspected cause for the decline of the only nest guarding cyprinid, the sunbleak This small fish has experienced high rates of mortality that have been associated with the spread of topmouth gudgeon; a cyprinid species from Asia, which is a healthy carrier of the rosette agent Salmon and cyprinids are highly susceptible to the Rosette Agent