R. Barzegar - -Department of Fisheries, Lahijan Branch, Islamic Azad University, Lahijan, Iran
M. Farokhrouz - Department of Fisheries, Lahijan Branch, Islamic Azad University, Lahijan, Iran
H. Khara - Department of Fisheries, Lahijan Branch, Islamic Azad University, Lahijan, Iran
A. Shenavar Masouleh - International Sturgeon Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran
M. Ahmadnezhad - - Inland Waters Aquaculture Research Center. Iranian Fisheries Sciences research, Agricultural Research, Education and Extension Organization (AREEO), Bandar Anzali, Iran

This study aimed to evaluate the effect of Myrtle, Myrtus communis, extract on hematological, immuno-physiological, antioxidant responses, bactericidal activity, and tissue histomorphology of gill and liver in juvenile Siberian sturgeon, Acipenser baerii. Siberian sturgeon were exposed to ۴ doses of myrtle extract including ۲۵% (۶۷.۴ mg/L; M۲۵), ۵۰% (۱۳۴.۹ mg/L; M۵۰), ۷۵% (۲۰۲.۰ mg/L; M۷۵), and ۱۰۰% (۲۶۹.۸ mg/L; M۱۰۰) of the maximum allowable concentration and a control treatment (without exposure myrtle extract). Hemoglobin and red blood cell  values were significantly increased in fish exposed to the myrtle extracts (p<۰.۰۵). The white blood cell was lower in M۲۵ and M۷۵, while the highest value was found in M۱۰۰ treatment (p<۰.۰۵). Myrtle extract did not affect the lymphocyte value in the course of exposure (p>۰.۰۵). The highest albumin and total protein levels were observed in M۲۵ and M۵۰ groups. The highest values of lysozyme and total immunoglobulin (Ig) activities were observed in M۵۰, M۷۵ and M۲۵, M۵۰, respectively (p<۰.۰۵). Superoxide dismutase and catalase activities of those fish exposed to M۵۰ and M۷۵ were significantly higher than the control and M۱۰۰ groups (p<۰.۰۵). The lowest glutathione peroxidase value was observed in the control group compared to the others (p<۰.۰۵). The severe changes such as adhesion and curling of gill lamella discern were observed in fish exposed to different levels of myrtle extracts. Moreover, in the control group, severe hepatocyte destruction was accompanied by nucleus pyknosis, but the severity of atrophy was observed in M۷۵ and M۱۰۰ treatments. Overall, the results suggested that myrtle in the range of ۶۷.۴-۲۰۲ mg/L could be applied as a stimulant agent to Siberian sturgeon aquaculture.

Exposure, Myrtle, Immuno-physiological, Siberian sturgeon