The Ph.D. viva session was held in the auditorium of the Iranian Fisheries Science and Research Institute for Mr. Seyed Mohammad Esmaeil Fakhar Zadeh (admitted for fall 2012) who was the research-based Ph.D. student. The title of his dissertation was "Investigating the antibacterial effects of normal forms and nano extract of oregano (Origanum Vulgare) on experimentally infected rainbow trout with Streptococcus iniae". The student completed his education in the field of aquatic health sciences at the Coldwater Fishes Research Center of Tonekabon. The doctoral thesis supervisors were Dr. Massoud Haghighi and Dr. Mostafa Sharif Rohani and the doctoral thesis co-supervisors were Dr. Isa Sharifpour and Dr. Mehrdad Hamidi. Members of the thesis examination committee were Dr. Seyed Jalil Zorieh Zahra, Dr. Mohaddes Ghasemi and Dr. Alireza Mirvaghefi. The doctoral thesis received a high grade.