Characteristics of histopathological changes in organs of banded catfish Pelteobagrus fulvidraco (Bagridae) from the Amur River basin

Abstract

The most frequently occurring pathological changes in the inner organs of banded catfish Pelteobagrus fulvidraco from the Amur basin, including those caused by parasites, are described. Eleven species of parasites are recorded. In gills of individuals from different areas, parasite occurrence varied from 7 (Lake Bolon) to 64% (bays of Bolshoi Ussuri Island), and in the liver tissue they varied from 7 (Lake Bolon) to 16% (Sindinskaya channel). Helminths cause moderate local changes in the liver, which manifests itself in the growth of connective tissue, incapsulation, and aggregation of pigmented macrophages around the capsule. Without relation to parasites, numerous changes were found in the liver: hepatocyte vacuolization (in some cases, focal), hypertrophy of some hepatocytes and an increase in their nuclei (polymorphism), karyopyknosis and diffuse necrosis of hepatocytes (in some cases, focal), edema of the liver, proliferation of bile ducts, and accumulation of pigments in melanomacrophyte centers and in proper hepatocytes. Hepatocyte necrosis—the most important indicator of the toxic impact of pollutants—was recorded in 44–50% of individuals from different areas of the Amur basin. In kidneys, vacuolization and hypertrophy of nephrocytes, coarse granularity of their cytoplasm, and karyopyknosis and necrosis of nephrocytes are observed. Rarely occurring changes in the kidneys include crystallury and proliferation of epithelium of ureters of unclear etiology. Some fish have pathological changes in two to three organs simultaneously.