Maria Kosior, WŁODZIMIERZ Grygiel, Jerzy Kuczyński, Krzysztof Radtke and Mirosław Wyszyński
Sea Fisheries Institute, Kołłątaja 1, 81-332 Gdynia, Poland

Key words: Baltic, disease symptoms, cod, herring, sprat, flounder, eelpout.

Abstract.
In the paper, disease symptoms are described observed in fish caught in the southern Baltic over the period 1994-1996. Fish were sampled from commercial and research catches. The main fish species examined were herring, sprat, cod and flounder, as well as other fishes occurring sporadically, such as eelpout, four-bearded rockling and others. Included among externally visible disease symptoms observed were ulcers, lymphocystis, melanism, and fin rot. Various types of  skeletal anomalies were also recorded. Ulcers, most frequently observed in cod, flounder and eelpout, were recorded sporadically in herring and sprat. Lymphocystis occurred mainly in flounder and herring. In flounder, a coocurrence of ulceration and lymphocystis was frequently observed. During research cruises, fish samples were collected for the determination of the heavy metal content.