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Determination of the sub-lethal effects of diazinon toxin carried out on steroidogenesis and quality of sexual production in male goldfish breeders. For this purpose, fish were first exposed to different lethal concentrations of diazinon toxin (9, 10, 11, 12.5, 15 and 20 mg/L) and LC₅₀ values were analyzed for 96 h using probit software.  The amount of LC₅₀ was 11.4 in 96 hours and fish were assorted according to 0, 0.25, 0.50 and 0.75 percent of LC₅₀ in 96 hours and were put there for 2 months. At the end of the experiment, the level of sex hormones and the quality of sexual production were studied in male broodstock. The results showed that diazinon toxin significantly reduced testosterone and 17-β-estradiol levels in the 0.50 and 0.75 mg/L treatments compared to the control (p<0.05). There was no significant difference in some sperm quality parameters such as sperm volume, sperm density and spermatocrit between the control and 0.25 treatment. By increasing the concentration of diazinon toxin (from 0.25 to 0.75 %), the duration of sperm motility decreased significantly. The percentage of motile sperm in the control treatment was higher than other treatment and it was decreased with increasing diazinon toxin concentration. The Gonadosomatic Index in the control treatment was significantly higher than the other treatments (p<0.05) and showed a decreasing trend with increasing toxicity. In conclusion, diazinon toxin in the aquatic environment, even at sub-lethal concentrations, causes undesirable changes in the sex steroid indices and quality of male gonads in goldfish.

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In this study, the effect of different salinity levels with salt of Lake Urmia was investigated on growth performance, body composition and some serum biochemical parameters of juveniles Caspian Kutum (Rutilus kutum). Fish with initial average weight of 1.05 ± 0.05g (±SD) were fed for 8 weeks in rearing tank. Juveniles Caspian Kutum were divided into four groups and treated with following preparation: control group salinity 0 ppt (fresh water), first treatment (salinity 5 ppt), second treatment (10 ppt) and third treatment (15 ppt). The results showed that the highest weight gain was observed in treatment 1 (p<0.05). Also, the Condition factor had significant differences between control and treatment 1 with other treatments (p<0.05). Survival was not affected by different salinity (p> 0.05). There was no significant difference in blood cholesterol levels between the experimental treatments, but there was a significant difference in hematocrit and glucose parameters (p<0.05). Body composition analysis showed that the experimental treatments had a significant effect on protein and fat levels but the moisture and ash levels were not affected by the experimental treatments. Generally, salinity level of 5 to 10 ppt of Urmia Lake salt had positive effect on growth, survival and blood parameters of juveniles Caspian kutum.
 

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In the present study, the effect of Pullulan coating with watercress extract on the quality and shelf life of fresh beluga sturgeon fillet stored in a refrigerator over a period of 16 days was investigated. First, the watercress extract was extracted by ultrasound and soxhlet (solvent) method and the amount of phenolic compounds and antioxidant activity of the extract (DPPH free radical activity test) were determined. The values of phenolic compounds for soxhlet extract were equal to 586.53 mg gallic acid per gram of dry weight and for ultrasonic extract was 879.57 mg/g dry weight and the antioxidant properties of watercress extracted by ultrasound were significantly higher than soxhlet method (p<0.05), so ultrasound extracts were added to the pullulan coating. Then, 4 treatments were included: control, pullulan coating, pullulan coating + watercress extract 500 ppm, pullulan coating + watercress extract 1000 ppm were analyzed by biochemical parameters such as peroxide value (PV), thiobarbithic acid (TBA), free fatty acid (FFA), total volatile base nitrogen (TVB-N) and pH). The results showed, natural preservation delayed chemical spoilage in compared with control treatment (p<0.05). According to the results pullulan coating + watercress extract 1000 ppm significantly retarded lipid oxidation by decreasing peroxide value and thiobarbituric acid production in the samples and it had the lowest total volatile basic nitrogen and pH (p<0.05). The control treatment had only the allowed chemical range for up to 6 days, but the treatment containing pullulan coating + 1000 ppm extract had the allowed values until the end of the storage period. The final conclusion showed that the coating of pullulan with watercress extract could act as a natural antioxidant, delaying chemical degradation and prolonging the shelf-life of fish fillets.