Parasitic, fungal, and bacterial pathogens involved in health problems of Siberian sturgeon (Acipenser baerii Brandt ۱۸۶۹) reared in Iran: Clinical and pathological findings

Sturgeons have been referred to as ‘primitive fishes’ among the bony fishes because their morphological characters have remained relatively unchanged. Farming sturgeons is an economically important profession in a number of countries in the world. Based on the nutritional value and demand for caviar and meat production, sturgeons are considered as one of the most high-valued food fish. Siberian sturgeon (Acipenser baerii Brandt ۱۸۶۹) is a marine acipenseriform food fish, which has been classified into the Acipenseridae family. Due to the interest of several fish farms in culturing sturgeon in Iran and the lack of sufficient relevant data, this study investigated parasite, fungus, and bacteria related health problems of an acipenseriform food fish species, the Siberian sturgeon (Acipenser baerii) from five fish farms between November ۲۰۱۸ and November ۲۰۲۱ in central Iran. Mortality of Siberian fish was reported in ۵ sturegon farms. The different types of pathogens found in these fish were investigated until the fish reached about ۳ kg of weight (۲+ years). A number of parasitic disease pathogens (monogenean Diclybothrium armatum and protozoan Trichodina sp.), fungus Saprolegnia sp., and bacteria Aeromonas sp. were identified in the moribound fish. Samples for histopathology were taken and studies under light microscopy. Then treatment of alive fish was performed according to the identified pathogens. And mortalities were stoped. In conclusion, due to the relatively large variety of these pathogens, consideration to few applied measures including full observance of the quarantine period, setting up an appropriate filtration and ventilation system, periodic use of efficient disinfectant compounds, and use of cement and fiberglass ponds as an ideal alternative for the earth ponds, are recommended to promote the fish health condition and prevent the development of infectious diseases in sturgeon fish farms.