Investigation the parasitic fan and fungal flora of fingerling stellate sturgeon (Acipenser stellatus, Pallas, ۱۷۷۱) in different salinities of the Caspian Sea

Considering the breeding of sturgeon for the production of the meat and caviar is one of the most important development programs of aquaculture, investigate the health condition of the breeding environment to collect information on the breeding condition is the best method for prevention of diseases and treating sturgeons. In order to do this study, ۳۶۰ pieces of stellate sturgeon with an average weight of ۱۰±۲ g were divided in four treatments groups including water with different salinities (۰-۰.۵ ppt, ۰.۵-۴ ppt, ۴-۹ ppt, and ۹-۱۳ ppt). After dividing the fishes into groups, the fingerlings fed for ۴ weeks. Finally, sampling carried out on ۷۲ of treatments fishes. After preparing the samples based on standard methods, parasitology and mycology studies, performed. Based on the results of this study, Trichodina sp. parasite was isolated from the gill and skin of stellate sturgeon in different salinity treatments investigated in this study. The results showed that with increasing water salinity, the number of Trichodina Sp. Parasites decreases. Based on the results, the highest and lowest number of Trichodina Sp. parasites was isolated from the fish treated with salinity of ۰-۰.۵ ppt and ۹-۱۳ ppt, with an average ۳-۵ and ۱ parasite. In this study no parasites were observed in the abdominal area and digestive system of fishes in different salinities. The results of this study showed that the highest and lowest isolated Fungi with ۱۸ and ۱۰.۳۳ respectively, are related to the gills and skin of fingerling stellate sturgeon of salinity treatments ۰-۰.۵ ppt and ۹-۱۳ ppt. According to the results of this study, the number of fungal agents decreases with increasing water salinity. The fungal flora isolated from the skin and gills of fishes and rearing water in different treatments in this study were: Cladosporium sp., Penicillium sp., Mucor sp., Aspergilus sp. and Yeasts.