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 Fresh fish is a highly perishable food item and spoils easily. In this research, after investigating the antioxidant properties of the Eryngium Campestre extract (Ece), its effect along with the sodium alginate coating was evaluated on the shelf-life of rainbow trout under refrigerated conditions (4°C) for 12 days. To assess the antioxidant properties of the extract, tests such as DPPH, total phenolics, reducing power, and ABTS were performed. Subsequently, samples treated with an Ece containing alginate coating applied via spray method were analyzed for chemical parameters (TBA, TVN, and pH) , microbiological parameters (total psychrotrophic and mesophilic bacteria), and sensory evaluations at four day intervals up to the 12 day. The results indicated that Ece possessed significant antioxidant properties. Furthermore, treatments that included the extract combined with the sodium alginate  coating significantly reduced pH, TVN, and TBA levels compared to the control sample (p<0.05). Microbial tests indicated that all treated samples inhibited bacterial growth when compared to the control sample, with a reduction of approximately 3 log CFU/g compared to the control group. In the sensory evaluation, treatments containing Ece and sodium alginate  yielded more favorable results than those of the control group. According to the obtained results coating the samples with sodium alginate  and Ece improved the microbial, chemical, and sensory properties and shelf life of rainbow trout in refrigerator conditions by about four days.
 

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The main concern in fish transportation is minimizing stress during transportation. In this study, the effect of zeolite and clove essence in terms of transportation on survival and stress rainbow trout was investigated. 4 treatments (each treatment included 3 replicate) including control treatment, clove essence (25 mg/l), zeolite (14g/l) and clove essence (25mg/l) + (14g/l) were considered. 156 fish (with average weight 80 ± 4.4 g) were randomly distributed with a 130 kg/m3 density. At time zero, 6, 12 and 18 hours after starting transportation, survival rates, cortisol and glucose levels (as indicators of stress) were measured and analyzed. In the end, results showed a significant difference in the survival rates that control treatment had the lowest survival rates (P

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Global aquaculture production has more than tripled during the last 15 years, and aquaculture is expected to account an increasing share in global seafood production. There are large differences among countries in the rate of growth and development of aquaculture. This review tries to explain the progress and problems of aquaculture during three last decades in Iran. The total production of Iran from aquaculture was 25,800 tons in 1994, approximately 8 percent of the total fisheries production. However, by 2008 it increased to more than 154,000 tons; 27% of total fisheries production. During the last decade, production share of different species in Iran has been variable. In the years 1998 and 2008 the highest percentage of aquaculture production was belonged to silver carp Hypophthalmichthys molitrix (50%) and rainbow trout (Oncorhynchus mykiss; 40%), respectively. The results showed that culture of rainbow trout has grown noticeably in the past two decades. At present, Iran has been acquired the first rank of rainbow trout culture in fresh water of the world. But in contrast, in recent decade shrimp aquaculture industry has failed due to white spot syndrome. Coastal and inland waters of Iran have more potential for aquaculture development. Recently, great sturgeon Huso huso and some species of barbus family have aroused interest from government and private enterprises for potential aquaculture use. Although aquaculture of Iran has shown a significant growth in the last decade, but it is concluded by introducing new species and overcome to present aquaculture problems in the country, the aquaculture production will be increased to several times.

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In order to understand the importance of particle size and agglomeration for nano-eco-toxicological studies in aquatic environments, the acute toxicity of two different types (suspended powder and colloidal) of silver nanoparticles (AgNPs) were studied in alevin and juvenilerainbow trout. Fish were exposed to each type of AgNPs at nominal concentrations of 0.032, 0.1, 0.32, 1, 3.2, 10, 32, and 100 mg/L. Lethal concentrations (LC) were calculated using a Probit analysis. Some physical and chemical characteristics of silver nanoparticles were determined. In the case of colloidal form, particles were well dispersed in the water column and retained their size; but in the case of suspended powder, particles were agglomerated to large clumps and precipitated on the bottom. In alevins, the calculated 96 h LC50 values were 0.25 and 28.25mg/L for colloidal and suspended powder AgNPs respectively. In the case of juveniles, the 96h LC50 of colloidal form was 2.16mg/L, but suspended powder did not caused mortality in fish even after 21 days. The results showed that both in alevin and juvenile stages, colloidal form is much toxic than suspended powder; this shows increase of nanoparticles size due to agglomeration, will reduce the toxicity. Silver nanoparticles are toxic materials and their release into the water environment should be avoided.

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The effect of the antioxidant extracts on the quality indices of rainbow trout fillet stored at refrigerator (4±1ºC) for 15 days was investigated. The fillets in 3 treatments, including salted in 10% brine, salted in 10% brine plus 1% nettle leaf extract, and salted in 10% brine plus synthetic antioxidant BHT were evaluated at every 3 days interval, using the quality indices including the free fatty acids (FFA), thiobarbituric acid (TBA), peroxide (PV), moisture content, pH levels and sensory characteristics. The results showed that TBA and FFA values increased significantly (p<0/05), but PV significantly decreased in all treatments during the course of storage (p<0/05). Samples containing antioxidants had significantly lower TBA, PV and FFA values in comparison with the control sample throughout the storage. Also, the methanol extract from nettle leaves (at 1% balance) controlled the TBA, PV and FFA indices and entirely replaced the synthetic BHT antioxidants (at 1% balance). Since the sensory evaluation (smell, texture, taste and after taste elements) showed no significant differences between the two antioxidants, both are recommended to preserve the quality of rainbow trout fillet. The nettle leaf extract was found to be more efficient on shelf life extension the fillet.

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Processing efficiency of rainbow trout, amounts of by-products and their nutritional value as well as some correlations between whole fish weight and products yield were evaluated. Results showed that efficiency decreased up to 87.56 ± 3.43% for gutted fish and it reached up to 56.69 ± 3.26% and 45.36 ± 2.37% for skined on and skinless fillets, respectively. The highest amounts of by-product were related to head and viscera which were 15.52 ± 2.00% and 12.62 ± 2.61% of body weight, respectively. A significant negative correlation was found between fish weight and head weight percentage (P<0.01). Also, the yield of headed and gutted product increased significantly by increase in fish weight (P<0.01). Among by-products, viscera and head were the richest sources of fat (17.4 and 13.0 % of wet weight) and skin contained the highest amount of protein (24.1% of wet weight). Moreover, a significant presence of the most important and health benficial omega-3 fatty acids was detected in both head and viscera. Viscera and bone were also found as rich source of iron mineral.

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The effect of pistachio green hull (PGH) at 0, 1.5, 4.5, 13.5 and 27% of the diet on the growth, blood biochemical and hematological parameters of rainbow trout (Oncorhynchus mykiss) of 27.03±0.58 g was investigated in a completely randomized design and in three replications with 14 fish individuals in each. At the end of 8 weeks feeding trial, blood samples were randomly taken from 4 individulas in each replication. Results showed significant differences (p<0.05) in SGR and FCR between 27% treatment and other treatments. No significant differences in Alb, Glo, Tg, GOT (p>0.05) were observed among treatments. Tp (2.76±0.15 g/dl), LDH (2139±44.26 IU/l), ALP (331.9±21.4 IU/l), GPT (407±17.82 IU/l), Hb (8.73±0.7 g/dl) and Hct (33.33±2.28%) had significant differences in group receiving 27% PGH compared with other group (p<0.05). Results showed that high levels of PGH in the diet of rainbow trout had adverse effects on health and growth factors.

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In a completely randomized design, the effects of two probiotic bacteria, Bifidobacterium animalis and B. lactis at four concentrations of 0 (control), 1×10⁹ (T1), 2×10⁹ (T2) and 3×10⁹ (T3) CFU 100g^-1 on nutritional parameters of rainbow trout fry (0.538 ± 0.197 g body weight) were compared for 60 days, with each treatment carried in three replications. A significant difference was observed between treatments and the control in protein and lipid gain and also body composition (p<0.05). Despite a significant difference of metabolic growth rate in T1 and T2 with T3 and the control, no significant difference was observed between T3 and the control. The results demonstrated that the use of thesebacteria could improve nutritional parameters and metabolic growth rate of rainbow trout fry.

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The effect of replacement of dietary soybean meal with broad bean flour on rainbow trout (Oncorhynchus mykiss) with average weight of 12.5 ± 0.09 g in 4 levels (15, 30, 45 and 60%) during 7 weeks trial was examined. The results showed that substitution of soybean meal up to 30% replacement) did not have any negative impact on fish growth performance. However, significant difference in red blood cells count and hematocrit percent were found between the experimental groups and the control (P<0.05).The highest amount of red blood cells (2.03± 0.23) and hematocrit (44.3±1.52) were observed in group of 15% replacement. Also, the results of blood biochemical parameters showed that cholesterol, total protein, albumin and globulin levels in experimental groups did not significantly differ between the control and other groups. The highest level of glucose (139.04±22.2) and triglyceride (323.54±11.8) were observed in the control group, but no significantly different (P>0.05) from 15% replacement. This study showed that up to 30% fish meal replacement with broad bean flour in the diet of rainbow trout had no negative impact on the growth performance, blood factors and survival of fish.

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The effect of packaging type on the shelf life of gutted farmed rainbow trout (Oncorhynchus mykiss) stored in refrigerator (3°C) was investigated. The fish was gutted and washed at room temperature. They were packed individually in polyethylene-polyamide bags in three experimental packaging: the presence of air, vacuum, and modified atmosphere (60% carbon dioxide, 10% oxygen and 30% nitrogen). The samples were stored in refrigerator  up to 15 days and evaluated for the microbiological enumerations, chemical and physical analysis at days 0, 3, 6, 9, 12 and 15. The numbers of mesophilic, enterobacteria and lactic acid bacteria in the various treatments were not significantly different, during the storage. The number of psychrotrophic bacterium was not significantly different up to the 12^th days of storage in all the experimental groups, whereas the bacterial count was significantly lower in the modified atmosphere packaging. Changes in the acid values and TBARS were not also significant in all the experimental groups during the storage. The amount of drip loss in all treatments increased with time. In the 12^th and 15^th days of storage, the loss was significantly higher in the vacuumed samples. In all treatments, the hardness value of meat was considerably decreased in the third day compared to the first day of storage. The present study revealed that if the rainbow trout properly washed and gutted in the hygienic conditions and stored at a suitable temperature, the shelf life was extended up to nine days without using any specific packaging. Furthermore, the packaging conditions used in this study did not improve the shelf life of the gutted farmed rainbow trout stored at 3ºC.

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The present study was to evaluate the impact of feeding level and fish size on the growth factors,carcass composition and digestibility of rainbow trout. Six experimental treatments were assigned by the use of three feeding levels (maintenance, medium and satiation levels) and two fish sizes (43.02 ± 2.93 and 231.32± 6.74g) according to a 3×2 factorial design.  There were three replicates for each treatment and the experiment lasted for 59 days. The results showed that there is a significant interaction effect between fish size and feeding level for body weight gain, final body weight and specific growth (p<0.05). Body composition (dry matter, energy, moisture, fat and protein) was affected by feeding level and size of the fish (p<0.05). However, the interaction effect between fish size and feeding level for body composition was not significant (p>0.05).The digestibility measurements showed that fish size and feeding level  changed  significantly digestibility of protein, lipid, energy and dry matter in rainbow trout (p<0.05). Maximum growth at satiation feeding level can reduce feed conversion ratio and increase waste production at both fish sizes.

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The chemical-morphological relationships in rainbow trout, Oncorhynchus mykiss, was assessed through photography in light room. The image data were transferred to a laptop and analyzed by MATLAB (Matrix Laboratory) version R2009a. The designated algorithm of 7 features, including length, height, area, perimeter, equivalent diameter, major and minor axis length were extracted from the images. Afterward, chemical compositions of the fish (including crude protein, crude fat, moisture content, pH value and leakage), were determined. Pearson's correlation coefficient was used to correlate visual and chemical properties. Factors were assayed with linear, logarithmic, exponential and power method. Results showed that pH, leakage, protein and fat had a good correlation with fish length, and moisture with fish perimeter, in Quadratic equation (R²= 0.993, 0.991, 0.991, 0.989 and 0.992, respectively). In conclusion, this methodology can be applied for automated chemical analysis and on-line monitoring in fish farms.

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Fish egg is an important source of polyunsaturated fatty acids, protein, minerals and vitamins. These are produced in the form of smoked, salted and then consumed. Initial preparations for washing eggs can have an important role on the finished product. To increase the strength of the egg membrane, waste removal, connective tissue and broken shells, fish eggs obtained after washing with different methods are carried out. In this study, three treatments have been utilized including, non-boiled water, boiled water cooled to3 to 5 °C, boiled water to 40 °C. Afterward, the two groups were prepared with 1.5% salt and no salt. Results of chemical, microbial and sensory tests were assessed on days 0, 12 and 24. It was shown that, cooled boiled water with a temperature of 3 to 5 °C with 1.5% salt and boiled water with a temperature of 40 °C with 1.5% salt gave the best and Non-boiled water with ambient temperature devoid of salt had the worst chemical andmicrobial results. In addition, cold boiled water with temperatures 3 to 5 °C with 1.5% salt showed the best sensorial results.    Boiled water with a temperature of 40 °C and non-boiled water without salt had the lowest sensorial results. 

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The effects of cooking methods on sensory attributes and physical properties (firmness, normal shear, cooking loss and color based on L*, a* and b*) of rainbow trout (Oncorhynchus mykiss) fillet was investigated. The study was based on application of autoclavingat 120 °C for 5 and 10 minutes, deep frying of the flour coated fillet at 180 °C for 2 and 5 minutes and microwaving at 600 watt for 2, 4 and 6 minutes. Cooking loss significantly differed among the cooking methods, the highest of which occurred in 6 minute microwaved treatment. The highest and the least color changes were, respectively, recorded in coated fillet fried for 5 minute and for 2 minute microwaved fillet treatment. In terms of normal shear results, control and 2 minute fried fillet treatment had the hardest tissue, respectively. Also the penetrate tests revealed a significant difference between control and other treatments (p< 0.05) as the hardest tissue was the one that fried for 5 minute and the softest one was the control. However, the highest score was allocated to the fried and 6 minute microwaved treatments by the panelists. Based on the sensory evaluation, fillet fried for 5 minute was found as a preferred cooking method.

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Key words: growth model, routine metabolism, rainbow trout , digestibility

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A 27 day study was undertaken to evaluate the effects of aqueous extracts of Hypericumperforatum on hemato-serological parameters and survival of rainbow trout (Oncorhynchusmikiss) under thermal stress (20 ± 2 ◦C). A total of 360 rainbow trout (97.2 ± 1.6g) were divided randomly into four groups and  immersed in different concentrations (0, 250, 500 and 750 ppm) (T0, T25, T50 and T75) of aqueous extracts of H. perforatum. The blood samples were collected on day 12 and 27 and hemato-serological parameters were determined. In stage 1, the total red blood cell, hemoglobin and hematocrit didn’t show a significant difference among controls and treatments but in stage 2, those parameters were significantly increased in T50 and T75 compared to T0 and T25.  The total white blood cell, lymphocytes, total protein, albumin, and total IgM showed a significant increase in treatments compared to control but the results in the neutrophils was opposit. The MCV and MCH didn’t significantly change in two stages but the MCHC of T75 were significantly higher than T0 and T25. The glucose of T50 and T75 were significantly lower than T0 and T25. The hepatic enzymes, ALT and AST of T75 significantly increased compared to other groups in stage2. The highest and lowest survival rates were observed in T50 and T0, respectively. Based on the results, it seems that Hypericumperforatum could control the effectsof stress and increase the survival rate of rainbow trout when exposed to chronic heat stress.

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The aim of this study was to assess the effects of triploidy induction on survival, growth performance, body composition and fatty acid profiles in rainbow trout. Eight female (1600±246 g) and 6 male (1393±186 g) of four-year rainbow trout broodstock were selected and stripped. Heat shock treatment achieved 10 min after fertilization, for 10 min and in 28˚C water bath. Based on red blood cell analysis, the overall triploidization success level was 87.1±1%.The survival rate from fertilization to eyed stage in triploid group (86.31 ± 1.21%) was significantly (p < 0.05) lower than that of diploid group (92.12 ± 1.59%). The survival rate from eyed stage to hatching in triploids (94.04 ± 1.33%) was significantly (p < 0.05) lower than that of diploids (98.10 ± 0.45%). Growth performance (initial and final weight, weight gain, specific growth rate and condition factor) was significantly higher in diploids as compared to triploids (p<0.05) after 38 days of rearing. Proximate compositions of fish including protein, fat and ash were not affected by triploidization, but triploids showed higher moisture content compared to that of the diploids. Moreover, the results showed that the levels of saturated fatty acids increased and the levels of unsaturated fatty acids decreased as an effect of triploidy induction. 

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The molecular characteristics of Yersinia ruckeri such as total proteins (TP), outer membrane proteins OMP) and lipopolysaccharides (LPS) in 34 isolates from rainbow trout farms in Tehran, Mazandaran and Zanjan provinces were determined, using SDS-PAGE method. The molecular weight (MW) for TP of all bacterial isolates was mostly less than 100 KD with a banding density in range 28 to 100 KD. Also, protein pattern of OMP consisted of three major bands with MW of 28-35 KD (two bands) and 10-17 KD (one band) plus some minor bands with MW of 48-75 KD and 17-28 KD. In addition, the LPS pattern of all bacterial isolates were less than 130 KD with the most band density in range 28-100 KD. These results show that the banding profile of TP, OMP and LPS of all isolates of Y. ruckeri were identical, demonstrating minimum heterogeneity among Iranian isolates of Y. ruckeri. Therefore, it is feasible for the formulation of a monovalent vaccine to yersiniosis in future.

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The antioxidant effect of sodium alginate coating containing vitamin C was examined on prolongation of the shelf life of rainbow trout (Oncorhynchus mykiss) fillets. The treatments included control group without any additive (C), sodium alginate 1.5% (A), sodium alginate 1.5% containing 5% Vitamin C (A+Vc). The treatments underwent periodic tests of proximate composition (moisture, protein, fat, ash and pH), chemical decays and oxidation tests, including total volatile base nitrogen (TVB -N), peroxide value (PV), tiubarbutic acid (TBA) and free fatty acids (FFA). Based on the statistical analyses, pH, TVB-N, PV, TBA and FFA in A+Vc were significantly (p<0.05) lower than C and A during storage in refrigerator. Significant increases were observed in all mentioned indices in all the  treatments in correlation with the duration of storage time in refrigerator (p<0.05). The coated treatments maintained better quality in comparison to the control group and treatment 3 (sodium alginate containing vitamin C) reduced oxidation of rainbow trout fillets during storage in cold condition (4± 1˚C). 

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.  The bacteriostatic and bactericidal activity of the ethanol extract of Kelussia odoratissima and chicory, Cichorium intybus L., against Streptococcus iniae and Lactococcus garvieae isolated from rainbow trout was investigated. Antibacterial efficiency of the plants was examined using agar well diffusion method and minimum inhibitory concentration. The MIC of the ethanol extract of K. odoratissima for S. iniae and L. garvieae were found to be 100 and 50 mg/ml, respectively and the MIC of the ethanol extract of C. intybus L for S. iniae was 50 mg/ml. Chicory didn’t have any inhibitory effect on L. garvieae.