Abstract
A population of juvenile (28 cm, 180 g) summer flounder Paralichthys dentatus developed severe coelomic distention, anorexia and lethargy over a period of 4 to 6 months. Gross internal lesions included a large coelomic mass that replaced the posterior kidney and yellow foci on the heart, spleen and liver. Histopathologically, the posterior kidney was obliterated by extensive granulomatous inflammation and rare calcified granulomas. Special stains revealed extracellular acid-fast bacilli in the areas of inflammation. An isolated bacterium belonging to the genus Mycobacterium was the presumptive causative agent of these lesions.
