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In order to determine the age and growth of Chub in the Gheshlagh River of Sanandaj, two areas were selected; one in upstream of the river (Naysar; high water quality) and the other in downstream (Soaryan; impaired water quality). A total of 280 fish specimen were caught during four seasons. The overall male to female ratio was 1:1.86 in Naysar and 1:0.61 in Soaryan. Both ratios were significantly different from the expected 1:1 ratio (P<0.01). The age of individuals was from 0⁺ to 5⁺ in both areas. The overall length-weight relationships were calculated as negative allometric in Naysar and isometric in Soaryan. The fork length and body weight of fish samples in Soaryan were significantly larger and heavier than those in Naysar in most of age classes and in both sexes. The average asymptotic length was calculated as 28.2 cm for male and 35.5 cm for female based on von Bertalanffy growth equation for all fish samples in Gheshlagh river system. The overall condition factor was estimated as 1.53 and 1.5 for male and female, respectively. In most of age classes, the condition factor was significantly larger in Soaryan fish samples in comparison to Naysar samples. Results showed that some Chub biological parameters were different between two study areas. These differences could be due to the entrance of Sanandaj wastewater into Gheshlagh River in Soaryan area.

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This study was aimed to evaluate the single and combined effects of sodium diformate as an acidifier and bacilli probiotics (Bacillus subtilis and B. licheniformis) on intestinal histomorphology of juvenile Salmo trutta caspius or 60 days. Hundred juvenile fish weighing 12. 6±1. 4 g were divided into 4 different treatments, including control, 0.4g B. subtilis+ B. licheniformis /kg diet, 0. 5g sodium diformate/kg diet and their combination (0.4g B. subtilis+B. licheniformis+0.5g acidifier sodium diformate/kg diet). Blood and intestine samples (9 fish/ treatment) were withdrawn at two different time intervals, i. e., days 30 and 60. The results showed that the microvilli height, parin lyer and the thickness of epithelium was reduced (p>0. 05) at day 30 as a result of single acidifier while the combined treatments led to either significant increase (Pp<0. 05) or no change as compared with corresponding single treatments and control group. Our data suggest that bacilli probiotic applied here was much successful to improve fish health status and growth performance rather than sodium diformate.

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The effect of inclusion of Nanoselenium to the commercial diet on the growth indices, liver enzymes and immune system of juvenile Acipenser stellatus was investigated. Individual 120 juveniles with an average weight of 21.93±1.03 g were fed with diets A, B, C and D (containing 0.1, 0.2, 0.3 and no Nanoselenium) for 8 weeks. At the end of the rearing period, blood samples were prepared from fish to evaluate liver enzymes and immune system indices. The final weight and daily growth in fish fed with diet A (0.1 mg /kg) were significantly higher than those fed with diet C (0.3 mg/kg). But there was no significant difference with fish fed with diet D (non Nanoselenium). The condition factor and protein efficiency ratio of fish fed with diet containing 0.1 mg/kg Nanoselenium was significantly higher than fish fed with diets C and D. There was no significant difference in the of total immunoglobulin (IgM) and complement (ACH₅₀) in different groups, But the secretion of lysozyme in fish fed with diet B was significantly higher than other groups. There was no significant difference in the activities of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase enzymes in fish fed with diets containing Nanoselenium compared to the treatment without Nanoselenium. It seems that inclusion of 0.1 and 0.2 mg of Nanoselenium per kilogram has a positive effect on the growth indices and immune system of Acipenser stellatus in growth stage.