Taurine is one of the most studied amino acids in aquaculture over the last decade. This study was conducted to investigate the taurine requirements in terms of growth, immune system, antioxidant enzyme activities and stress response of beluga (Huso huso) (209.1 ± 23 g) in both fresh water (FW) and brackish water (BW: 15 ppt). Twelve experimental tanks with six taurine levels (2.1 g/kg_21.8 g/kg), for FW (Tau2.1, Tau4.3, Tau7.1, Tau12.3, Tau16.7 and Tau21.8) and BW (BwTau2.1, BwTau4.3, BwTau7.1, BwTau12.3, BwTau16.7, and BwTau21.8), were designed to feed and farm fish for eight weeks. Generally, fish farmed in BW had better growth and immune response performance compared with FW. The quadratic relations for pooled data determined taurine requirements in terms of weight gain (12.1 g/kg), lysozyme (13.5 g/kg), IgM (12.7 g/kg) and osmolality (15.1 g/kg) (p<0.05). Furthermore, taurine requirements to obtain the minimum cortisol before and after stress were 10.4 g/kg and 14.3 g/ kg, respectively. When we exposed fish to high stock density stress (12 kg/m 3 for 4 hours), those fed dietary 16.7 and 21.8 g/kg had more stable glucose, cortisol and lactate before and after stress in both FW and BW. In conclusion, beluga fed diets with 12.3 g/kg and 16.7 g/kg taurine in both FW and BW groups had the best performance regarding growth and health status, respectively.

In order to determine the chelating effect of activated charcoal, a total of 150 beluga (270 g) were fed for 60 days with a diet containing 0 (control), 5, 10, 15 and 20 g activated charcoal per kg. Afterwards, the fish were subjected to challenging with 1 mg/L of each of heavy metals including lead, cadmium and copper during seven days. As results, the highest percentage of body weight gain, specific growth rate, condition factor, protein efficiency ratio and the lowest feed conversion ratio before and after challenging with heavy metals were obtained in 15 g treatment with significant differences comparing to other treatment (p < .05). In all treatments, considerable differences were observed between two experimental stages of all parameters except condition factor and feed conversion ratio (p < .05). No mortalities were observed during the experiment. Before challenging with heavy metals, 15 g treatment showed the lowest activities of AST and ALT enzymes, and uric acid, protein, albumin and cholesterol amounts. The minimum amounts of creatinine and glucose were recorded in the control and 20 g treatments respectively. The highest levels of these parameters, except for creatinine and uric acid, were measured in the control group.After challenging with heavy metals, the lowest levels of AST and ALT enzyme activities, uric acid, creatinine, and glucose, and the highest amounts of protein, albumin and cholesterol belonged to 15 g, whereas the results in the control group were almost opposite. In all treatments, significant differences were observed between two experimental stages of all parameters except AST, uric acid, glucose and cholesterol (p < .05). In the pre-challenge stage, the maximum amount of carcass protein was observed in 15 g while the differences in lipid content were not significant (p > .05).Moreover, the highest contents of moisture and ash were measured in the control group and 20 g respectively. After the challenge, the highest values of protein and lipid were quantified in 15 g, while the maximum values of ash and moisture were observed in 20 g and control group respectively. Also, significant differences were observed just in ash and moisture amounts in both stages (p < .05). Accumulations of cadmium, copper and lead were maximal in the control group in both stages, and their amount were decreased in sample with 15 g of activated charcoal until they reached How to cite this article: Samadaii S, Bahrekazemi M. The effect of diets containing different levels of active charcoal on growth performance, body composition, haematological parameters and possibility of heavy metals detoxification in big sturgeon (Huso huso). Aquac Res. 2020;51:91-101. https ://doi.

This study was conducted to investigate the effect of cinnamon in high- and low carbohydrate diets on the physiology of rainbow trout (Oncorhynchus mykiss (16.12±1.33 g). Six experimental diets including control/LCarb (200 g/kg carbohydrate), LCarb-3C (200 g/kg carbohydrate, 30 g/kg cinnamon), LCarb-5C (200g/kg carbohydrate, 50 g/kg cinnamon), HCarb (300 g/kg carbohydrate), HCarb-3C (300 g/kg carbohydrate, 30 g/kg cinnamon), and HCarb-5C (300 g/kg carbohydrate, 50 g/kg cinnamon) were formulated to feed fish for eight weeks. The results showed that fish fed dietary LCarb-3C (72.64 g) and LCarb-5C (73.17 g) had higher weight gain as compared with treatments without cinnamon (P<0.05). Blood performance in LCarb3C (67.10) was significantly higher than the HCarb-3C group (P<0.05). Fish fed dietary LCarb-3C had the best performance so that cinnamon in this group lowered glucose, total cholesterol, and low-density lipoprotein, improved total protein, and highdensity lipoprotein contents. Supplementation of this herb also improved protease and lipase in LCarb-3C and LCarb-5C groups as compared with control. Individuals fed supplemented diets but not HCarb had a higher superoxide dismutase activity when compared with the control group (P<0.05). Generally, cinnamon improved parameters in this study in fish fed a low-carbohydrate diet rather than a high-carbohydrate diet.

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The effects of three anesthetics, clove oil (CO) (

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Ethylenediaminetetraacetic acid (EDTA) is one of the most popular chelating agents. This study was conducted to investigate the effect of EDTA on the growth and health physiology of beluga (38.47 ± 0.58 g) before and after heavy metal stress (HMS). Five experimental diets, including control, 0.5EDTA, 1EDTA, 1.5EDTA and 2EDTA, were formulated to feed fish for eight weeks. The results showed that fish was fed with dietary 1.5EDTA (108.37 g) had a higher weight gain as compared with control (p < 0.05). Blood performance in the control group after HMS decreased but not in fish fed supplemented diets with EDTA. EDTA reduced uric acid and creatinine levels in beluga. Fish fed dietary 1.5EDTA had a higher value of blood performance (55.17), glucose (50.3 mg/dl), superoxide dismutase (SOD U/ml) (75.8) and glutathione peroxidase (234.0 U/ml) after HMS as compared with the control. Additionally, lower values of uric acid (3.05 mg/dl), creatinine (0.27 mg/dl) and AST (61.47 U/ml) after HMS in the 1.5EDTA group were observed (p < 0.05). Correlation analysis revealed a strong positive correlation between EDTA level and protein efficiency, lipid efficiency, and blood performance and a strong negative correlation with some parameters after stress, including SOD, glucose, uric acid, creatinine and aspartate transaminase (p < 0.01). In conclusion, feeding fish with the 1.5EDTA diet improved growth and detoxified heavy metals.

The study evaluated the effects of Levamisole, Quil-A and Cinnamon on growth, hematological and immune parameters of marmalade cichlid. Fish (2.00 ± 0.02 g) were fed diets supplemented with 0.2% Levamisole, 0.5% Quil-A and 1% Cinnamon for 60 days and the control group was fed with basal diet. The highest weight gain and condition factor were observed in fish fed diet enriched with Levamisole followed by Quil-A. There was no significant difference between the three treatments in specific growth rate (SGR) (p>0.05). However, the SGR showed a significant difference in the control group (2.16 ± 0.02% day-1) compared to other treatments (p<0.05). No significant difference in survival rate was observed between treatments (p>0.05).