The objective of the study was to evaluate the efficacy of 2-phenoxyethanol (2-PE) as an anesthetic in great sturgeon under two experiments. First, fish were exposed to 0.1, 0.3, 0.5, 0.7 and 0.9 mL/L 2-PE, and time to induction (deep anesthesia) and recovery from anesthesia were measured. At concentration of 0.1 mL/L, 2-PE failed to induce deep anesthesia in fish, whereas at concentrations of 0.7 and 0.9 mL/L, all the fish were anaesthetized within 3 min of exposure. For assessing the impact of effective concentrations of 2-PE on physiological responses of great sturgeon, hematological indices, plasma metabolites, electrolytes, enzymes and cortisol levels were measured. The use of 2-PE induces a significant increase in RBC values at 0.3 mL/L concentration and a parallel increase in hemoglobin and hematocrit values. 2-PE anesthesia had no effect on WBC, MCV, MCH and MCHC levels when compared to control group. Serum glucose, cholesterol and cortisol levels were significantly high in 0.3 and 0.5 mL/L 2-PE. Moreover, AST levels were increased in fish exposed to the 0.3 mL/L 2-PE comparing with the control group (P < 0.05). There were no significant differences in serum levels of total protein, triglycerides, ALP, ALT, Cl(-), Na(+), K(+), Ca(2+) and Mg(2+). In this study, alteration in hematological and serum biochemical indices was time-dependent. This study demonstrates that rapid induction of deep anesthesia with a relatively high concentration of 2-PE (0.7 and 0.9 mL/L) was associated with the lowest effects on the hematological and serum biochemical indices in great sturgeon and therefore would be recommended as eligible doses for hematological studies in this species.

The anaethetic effects of 2-phenoxyethanol (2-PE) on possible primary (cortisol level) and secondary (hematological indices and glucose level) stress responses were studied in Persian sturgeon (Acipenser persicus). Fish were first exposed to 0.1, 0.3, 0.5, 0.7, 0.9 and 1.1 ml L À1 2-PE, and the time to induction (deep anaethesia) and recovery were measured. At a concentration of 0.1 ml L À1 , 2-PE failed to induce deep anaethesia in fish, whereas at concentrations of 0.7, 0.9 and 1.1 ml L À1 all fish were anaethetized within 3 min of exposure. For assessing possible stress effects caused by effective concentrations of 2-PE, the hematological indices, serum cortisol and glucose were determined in the deeply anaethetized fish as stress indicators. The 2-PE exposure resulted in significant increases in red blood cell (RBC) values at 0.3 and 0.5 ml L À1 ; parallel increases in hemoglobin values were also observed at these concentrations (P < 0.01). Moreover, a lower concentration of 2-PE (0.3 ml L À1 ) caused a significant increase in hematocrit values (P < 0.05). Among the hematological indices, mean corpuscular volume (MCV) values decreased at 0.5 ml L À1 when compared with the control and other groups (P < 0.05). Serum cortisol level was elevated at 0.3, 0.5 and 0.7 concentrations of 2-PE (P < 0.01). The glucose level followed a trend similar to that observed for cortisol. The outcome of these experiments shows that 2-PE at a concentration of 0.9 ml L À1 is a suitable anaesthetic for Persian sturgeon. This study demonstrates that rapid induction of deep anaethesia with a relatively high concentration of 2-PE (0.9 and 1.1 ml L À1 ) was associated with the lowest effects on signs of physiological stress in Persian sturgeon.U.S.

The aim of this study was to investigate the acute effects of nanosilver as potentially dangerous additives to assess the mortality effects of this nanotechnology product on one of the valuable and important species of Caspian Sea. We compared the toxicity of different sized silver nanoparticles (AgNPs) which are being widely used with Iranian consumers due to its unique antimicrobial activity. Ecotoxic assessments of AgNPs from two Iranian companies of nanotechnology (Nanocid1: average particle size of 18 nm and Nanosil1: average particle size of < 100 nm) and silver salt (AgSO 4) were conducted on the Caspian roach (Rutilus rutilus caspicus). Fish were exposed to technical doses of Nanocid (0, 0.01, 0.1, 0.5, 1, 2.5 and 5 ppm), nominal doses of Nanosil (0, 0.2, 2, 20, 50, 100 and 200 ppm) and technical doses of silver sulfate (0, 0.001, 0.01, 0.1, 0.5, 1 and 2 ppm). The median lethal concentration (LC 50) was determined with probite analysis. The estimated 96-h LC 50 values (95% confidence limits) for Nanocid, Nanosil and silver salt were 0.