Lymphocystis Disease in American Plaice of the Eastern Grand Bank

Abstract

Lymphocystis infection is described and figured, both for gross appearance and for microscopic sections of American plaice, Hippoglossoides platessoides (Fabricius), from the eastern slope of the Grand Bank. This infection was first noticed in American plaice from this area in September 1960. Between July and early October 1964 about 1% of the American plaice of commercial size caught on the southern part of the eastern slope of the Grand Bank showed lymphocystis nodules, usually between 0.6 and 2.0 mm diameter, on the surface of the skin, on the upper and lower surfaces and on the fins, either separate or in tumours made up of individual nodules surrounded by connective tissue and covered externally by epidermis.