Morphometric and Molecular identification of Gyrodactylus sprostonae in Guilan Province warm water fishes with an attitude of intensity and prevalence in selected farms

Gyrodactylus, a member of Platyhelminthes, is one of the most common external parasites on freshwater and marine fish. This parasite mostly appears on skin and fins but rarely on gills of fish. Gyrodactylus can cause disease and mortality in wild and domestic populations of fish. In this study Gyrodactylus specimens removed by wet mounts of skin and fins of Cyprinus carpio, Hypophthalmichthys molitrix and Hypophthalmichthys nobilis in Guilan Province fish ponds and analyzed by a light microscope. The morphometrical identification of Gyrodactylus specimens was performed using the measurements and drawing of opisthaptoral hard parts like as anchor, marginal hook, ventral bar and dorsal bar. The molecular species description was based on polymerase chain reaction (PCR) of a partial sequence of the 5.8S region of ribosomal RNA, and a partial sequence of the internal transcribed spacer 2 (ITS2) of ribosomal RNA. The nucleotide sequences of the PCR products were compared with other sequences registered in GenBank. Based on the morphometric analysis and sequencing, the Gyrodactylus specimens were identified as Gyrodactylus sprostonae. The abundance of this parasite in investigated fish ponds of Guilan Province were 21.42, 6.17, 21.95 and zero for C. carpio, H. molitrix, H. nobilis and Ctenopharyngodon idella respectively.