Morphological Approaches in Solving Regional Problems of Aquatic Animal Pathology

The purpose of the study is to investigate the pathomorphological picture of a previously undescribed disease in fish of the species silver crucian carp (Carassius gibelio) in the Novosibirsk region. The work is devoted to identifying patterns and causal relationship in the development of diseases of aquatic animals, issues of pathogenesis and pathomorphological diagnostics of diseases in fish, first discovered in silver crucian carp in reservoirs of the Novosibirsk Region in 2020 and Krasnoyarsk Krai in 2022. The contribution of morphology to the overall result and the establishment of a pathological diagnosis occupy an important place in the general structure of disease diagnostic methods. In this regard, samples of material from 23 individuals of the silver crucian carp species with pathological formations in the head area were examined using light microscopy in transmitted and reflected light. Depending on the degree of disruption of the epithelial cell structure, namely the polarity of keratinocytes, changes in stratification and increasing cell atypia, we have found fish with varying degrees of severity of the pathological process - from epithelial hyperplasia and dysplasia to the appearance of cells with signs of malignancy. In fish with a small epithelioma, as a rule, only signs of hyperplasia of the basal layer epithelium are noted, which is probably a reflection of the initial stage of the tumor process. A comparative analysis of the morphological picture of this disease with similar disruptions in the structural organization of epithelial tissue in fish and other animals, as well as humans, indicates its viral nature. The pathology we discovered in silver crucian carp has a similar pathomorphology when the epithelium is affected by the human papilloma virus. The clinical and morphological picture of the totality of the identified morphofunctional changes is characteristic of herpes of carp fish and has not previously been recorded in the water bodies of the Novosibirsk region.