**Acknowledgement**

The authors thank the personnel of the Shahid Rajaei Aquaculture Center for their assistance. We are also grateful to Professor Mehdi Soltani from Faculty of Veterinary Medicine, University of Tehran, Dr Ali Shahreki from Medicine Science University of Zahedan, Iran, Professor Masoud Rezaei from Tarbiat Modares University, Iran, Professor Wolfgang Kneifel and Professor Konrad Domig from University of natural Resources and Life Sciences, Vienna, Austria for their helpful opinions. Some part of this research was funded by Tarbiat Modares University, Tehran, Iran.
