Histophatology and Hematology in rainbow trout (Oncorhynchus mykiss) following experimental infection with Aeromonas hydrophila

To investigate the hispathological characteristics in liver, kidney, spleen and gills of rainbow trout, Oncorhynchus mykiss following experimental infection with Aeromonas hydrophila, septicemia agents in fishwere infected through injected intraperitoneally and direct contact with 107 bacteria per liter solution. Mortality and clinical diagnostic were recorded in experimental periods. After 14 days, blood and tissues were sampled of survival fish. A significant decreased in RBC, Hb, lymphocytes and monocyte (p <0.05) and significant increase in WBC and neutrophile (p <0.05) is the most important changes in hematological index of infected fish by A.hydrophila. Presence of bacteria in the tissues were confirmed the by biochemical tests. Tissues were normal in the control group. The apparent disorganization of live cells, cytoplasmic and nuclear material deposition, the rupture of blood sinuses, hypertrophy of hepatocytes, degeneration, hemorrhage, vacuolization of cell cytoplasm in liver tissue; a significant deposition of hemosiderin granules in a melanomacrophage center and morphological alterations in ellipsoid cells in spleen tissue; degeneration and necrosis of renal tubules, glomerular lesions, shrinking of the glomerulus and enlargement of space inside Bowman’s capsule, dwindling of the tubular lumen in kidney tissue; hyperplasia, necrosis of epithelial filament, shortening of secondary lamellae and lamellar fusion in gills are important histopathological damage observed in tissues of infected fish with A.hydrophila.