The survey of contamination and geographical distribution and host scope of Diplostomum spataceum infestation in Oncorhynchus mykiss of West Azerbaijan Province-Iran

This survey was concluded to study identification, distribution determination of Diplostomum spataceum infestation and it's possible causes in west Azarbaijan (Iran)cold water fish farms.for this purpose among 40 propagated and cultured Rainbow trout, Onchorhynchus mykiss, farms around West Azarbaijan Province of Iran, 312 individuals were examined parasitically randomly during various harvesting seasons.52 infested fishes with 16.6% were found and 12 farms that 9 farms enjoyed river water and 3 farms had well water sources to provide their water supply. Infested farms were found around Makou, Urmia, Piranshahr, Naghadeh, whereas, Urmia and Tekab infested farms were caused by exotic infestation of infected fingerlings. It was shown that most of the farms which had Diplostomum spataceum provided their water supply from river alone or with the other water sources.The most infection rate with 39% was observed in summer and minus infection rate 6.6% in spring was observed.These farms enjoyed of sedimentation ponds that can play a key role in complementing the life cycle of the parasite. A great accumulation of Vermins, specially Snails were observed around and in the sedimentation ponds. In the meanwhile, 70 cases of these snails were collected in which Lymnaea sp., bivalves and planorbis genus have been distinguished. In autopsies of Lymnaea snails, a stage of sporocyst form of parasite was observed.