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 use of silver nanoparticles (Ag-NPs) is rapidly increasing, but there are limited data on their effects on the aquatic environment. The present study aimed to determine the acute toxicity and evaluate the effect of subacute concentrations of Ag-NPs (Nanocid®: average particle size of 61 nm) on hematological and plasma biochemical indices of silver carp, Hypophthalmichthys molitrix, after 3, 7 and 14 days. The 24-, 48-, 72- and 96-h median lethal concentration (LC50) values of Nanocid for silver carp were estimated at 0.810, 0.648, 0.383 and 0.202 mg/L, respectively; 20% and 10% of the 96-h LC50 values (0.04 and 0.02 mg/L) were selected for subacute study. Red blood cell (RBC) count, hemoglobin (Hb) count and hematocrit (Hct) level were significantly reduced at both concentrations tested (p < 0.05). White blood cell (WBC), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), cortisol and glucose levels in Nanocid-treated groups were significantly higher than the controlled group at experimental periods (p < 0.05). In conclusion, Ag-NPs intoxication resulted in erythrocyte reduction, hematological disturbances, leucocytosis and stress response in silver carp and offered a simple tool to evaluate toxicity-derived alterations.

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The effect of two insecticides, diazinon and deltamethrin, was investigated on hematological parameters and gill morphology in iridescent shark, Pangasius hypophthalmus. Fish were exposed to 0.5 and 1 ppm diazinon as well as 0.015 and 0.020 ppm deltamethrin over a 7-day period. Both insecticides caused leukocytosis, lymphopenia, neutrophilia as well as increases in red blood cell (RBC), hematocrit (Ht), hemoglobin (Hb) and mean corpuscular volume (MCV). Morphological gill damages were observed in fish exposed to both pesticides. It is suggested that diazinon and deltamethrin changed immune function and induced gill damages which could be the reason of increase in RBC, Ht, Hb and MCV in iridescent shark.

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