Cyprinid herpesvirus-3 (CyHV-3) is recognised as a pathogen which causes mass mortality in populations of carp, Cyprinus carpio. One of the characteristic symptoms of the disease associated with CyHV-3 infection is the occurrence of skin lesions, sloughing off the epithelium and a lack of mucus. Furthermore, fish then seem to be more susceptible to secondary infections by bacterial, parasitic or fungal pathogens which may cause further mortality within the population.