M Mesbah - Department of Aquatic Animal Health and Disease, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Iran
B Mokhayer - Department of Aquatic Animal Health and Disease, Faculty of Veterinary Science, Tehran University, Iran
B Jalali - Department of Aquatic Animal Health and Disease, Islamic Azad University, Tehran, Iran
G Hamidian - Department of Aquatic Animal Health and Disease, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Iran

Objective: Shadegan Wetland is one of the widest wetland lying in Khouzestan Province. This major wetland is polluted due to agricultural drainage flowing from industrial and human wastes causing change in organism and life environment of local fish. The aim of the present study was to investigate the effects of the environmental factors on the occurrence of Dactylogyrus carassobarbi on Barbus sharpeyi inhabiting in Shadegan Wetland. Method & Materials: 176 fish were taken alive or recently captured from four sites were carried fresh with ice to the laboratory, during 60 days in the middle of each season in 2005. They were treated as standard test. SPSS, version 11.5 used for statistical analyses. Results & Conclusion: The number of D. carassobarbi was significantly different in each sampling area, both in different seasons or in the same season. The average number of the parasite in the anterior half of gill filaments was significantly more than that in the posterior half (P<0.01). The result of this study showed that D. carassobarbi has a tendency in attachment to the anterior half of the gill. The average number of the parasite on gill arches did not show any significant difference (P>0.05). Therefore, it can be concluded that study of each gill arch (right or left) can be representative of the total monogenic infestation.

Dactylogyrus carassobarbi, Barbus sharpeyi, Environmental factors, Shadegan wetland