Study on Trichodina reticulata and Diplostomum spathaceum in larvae and fingerlings of the Persian sturgeon (Acipenser persicus)

摘要

Increased interest in fish culture has increased awareness of parasites that affect fish health, growth and survival. The present study was conducted in two phases on Persian sturgeon (Acipenser persicus) larvae and fingerlings in spring and summer 2010. In the first phase of this study, a total of 300 specimens of larvae were collected on five days after the onset of exogenous feeding. The second phase was conducted with 300 specimens collected from five earthen ponds, which included 150 fingerlings collected 20 days after stocking and 150 fingerlings collected at the time of their release into rivers. No parasite was observed in the sturgeon larvae on 5 days after the onset of exogenous feeding. However Trichodina reticulata were observed in the fingerlings (prevalence = 30 – 66.7%) 20 days after they were transferred to the earthen ponds. At the time of their release into the river, in addition to T. reticulata (prevalence = 66.7 – 100%), Diplostomum spathaceum (prevalence = 16.6% - 36.6%) were also observed in the sturgeon fingerlings. It is evident from the present study that Trichodina and Diplostomum infection occurs after fingerlings are released into the earthen ponds and gradually increases with the progress in the rearing period. Significant differences were observed in the mean intensity of T. reticulata infection in sturgeon fingerlings during two stages of rearing into earthen ponds.