In this study, straminipilous (fungus-like) organisms growing on the eggs of Acipenser schrenckii, Acipenser sinensis, Acipenser medirostris, Huso dauricus, Acipenser mikadoi and Acipenser baerii, in water bodies of different trophic levels, were investigated. A total of 54 species were recorded, with the largest number of species occurring on eggs in the water from the Biała River (very biogenic), and the smallest number on eggs in the water from the Supraśl River (poorly biogenic). Achlya polyandra, Aphanomyces irregularis, Saprolegnia ferax, Saprolegnia parasitica, Leptomitus lacteus and Pythium diclinum were found on the eggs of all of the investigated species of sturgeon fish. However, Aphanomyces frigidophilus, Aphanomyces invadans, Aphanomyces piscicida, Dictyuchus pisci, Saprolegnia bhargavae, Saprolegnia polymorpha and Saprolegnia salmonis were observed rarely in Polish waters. Amino acid, carbohydrate and urease tests were performed on these particular genera of fungi.