What is a characteristic feature of the viral infection known as lymphocystis?

Lymphocystis is a viral infection that primarily affects fish, particularly those in freshwater and marine environments. A hallmark characteristic of this disease is the formation of distinct whitish tan plaques or nodules on the skin and fins of infected fish. These growths are caused by the proliferation of fibrous tissue in response to the viral infection, leading to the typical appearance that can be observed by aquarists and veterinary practitioners alike. The lesions can vary in size and may eventually cover larger areas of the fish's body but are generally identifiable by their whitish to tan coloration.

The other manifestations mentioned, such as red skin lesions, presence of parasites, or blackened patches, do not align with the typical clinical presentations of lymphocystis. Instead, those features may be associated with other conditions or infections in aquatic species, thus reinforcing the correct identification of lymphocystis by its characteristic whitish tan plaques or nodules.