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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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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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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 effect of different lipid extraction methods (including, Bligh & Dyer, Smeds, Bligh & Dyer using Dichloromethane, Folch, Roese Gottible, Soxhlet used petroleum ether – dry and wet-  and Soxhlet used N-hexane) on total fat and fatty acid composition in rainbow trout (Oncorhynchus mykiss) was investigated. According to the results, the Bligh & Dyer method showed a higher fat extraction efficiency than Soxhlet (wet), Smeds and Roese Gottible, while no significant difference was observed with the other methods. No significant differences were found in total SFA, total MUFA, and total PUFA of different extraction methods. The omega-3/omega-6 ratio ranged between 0.20-0.29. The highest amount of polyene index (PI) was 0.34, but no significant differences were found between different extraction methods. Taking fat quality and quantity, finance, toxicity, and theease of operation, the most efficient method for rainbow trout lipid extraction was the “optimized Bligh & Dyer using Dichloromethane”.  

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  The biogenic amines content of whole rainbow trout (Oncorhynchus mykiss) and its related bacterial load (psychrotroph and psychrophiles, pseudomonads and mesophiles) were monitored during ice storage in a period of eighteen days (zero, 3, 6, 9, 12, 15 and 18). The levels of putrescine, cadaverine and histamine and bacterial loads increased (P<0.05) during storage but tyramine was not detected in any of the samples. Initial concentration of putrescine was 0.4 and finally reached to 8.97 mg/g, and psychrotroph and psychrophiles were the dominant microorganisms. The best correlatios were found among putrescine and psychrotroph and psychrophile and its regression equation derived relating PUT, pse and psy (R=./98): [PUT =0.83 pse + 0.69psy+ 0.41[. In adition another regression equation derived relating CAD and time (R=0.955): [CAD =0.576 time - 3.49[.It is therefore concluded that although the quality control of Rainbow trout can be approximately estimated by measurement of either putrescine or psychrophiles with the usage of derived equation, but it's much better to evaluate some of these factors simultaneously to accomplish a precise quality assessment.

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    Salting and vacuum packaging, each of them has disadvantages for fish preservation in non-frozen mode. This study was aimed to investigate the The effect of light salting, vacuum packaging and their synergistic effect on on shelflife of rainbow trout (Oncorhynchus mykiss) fillet during storage at 4°C±1. For this purpose the rainbow trout fillets were brined in 10 salt solution and vacuum packaged. Measuring of PH, total volatile bases nitrogen compounds (TVB-N), tiobarbitoric acid (TBA), total viable microbial count (TVC) and sensory evaluations, were performed during 18 days in refrigerator temperature. Obtained results showed that all of chemical and microbial indices increased during storage period. PH, TBA and TVB-N indices and microbial growth in salted, vacuum packaged was lower than other treatments and in light salted treatment was lower than control group (p<0.05). The results of sensory evaluations showed that light salting of rainbow trout fillet situation improved these indices rather than control group. Salted vacuum packaged treatments had a better sensory evaluations scores than salted treatment (p<0.05). with regarded to allowable restrict of TVB-N indices (25 mg/100g fillet) and total viable count (6 Log cfu/g) and also sensory evaluations, light salting and salted vacuum package treatments increased the shelflife of rainbow trout fillet in 4°C about 3 and 7 days, respectively and the major problems of each method of salting and vacuum packaging was removed.

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Aims: The present study intends to assess the toxicity of CuO and ZnO nanoparticles (NPs) at laboratory conditions on some pathogenic bacteria for the reared fish, as well as, a bioassay on rainbow trout.
Material & Methods: For this purpose, the sensitivity of them to the mentioned NPs with a reference antibiotic (florfenicol) was assayed through the well diffusion method, as well as, minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) were determined by microdilution technique. On the other hand, the lethal toxicity test has been accomplished to the calculation of median lethal concentration (LC50) on some rainbow trout (55.3±7.6 g) in static condition for the 96 consecutive hours. We use one-way ANOVA and Probit regression in order to data analysis.
Findings: Results show that NPs of copper oxide and zinc oxide could significantly inhibit the growth of Streptococcus iniae or kill it at 0.18 and 0.24 µg/ml and more, respectively. The comparison between LC50-96h quantities of CuO NP (107.4 µg/l) and ZnO NP (102.3 µg/l) indicated that the CuO NP has more toxic potential.
Conclusion: According to the laboratory findings, the susceptibility of S. iniae and L. garvieae to ZnO NP were close to florfenicol. The mortality in the fish species due to lethal toxicity would occur if the effective concentration of NPs on the bacterial pathogenic agents being used directly.

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The present study intends to assess the effects of Na diformate oral use with citric acid on some skin mucosal immunity indices (total protein, total immunoglobulin (TIg), lysozyme, protease, esterase, and alkaline phosphatase (ALP)) of rainbow trout following experimental challenge with Yersiniosis agent (Yersinia ruckeri). Subsequent to the determination of the 7-day median lethal dose (LD50) of Yersinia ruckeri, fish were stocked in eight groups and two repetitions. The acidifiers separately with a dose of 0.2%, and combined 0.1+0.1% was added to the commercial diet. Five days after inoculation, feeding of fish with acidifiers commenced, and following 15 days, the mucus samples were gathered from the skin of anesthetized fish to measure immune indices. Results showed that the 7-day LD50 of Y. ruckeri was 8.91×105 CFU/ml. In the main experiment, findings indicated the significant effect of Na diformate on the increased levels of mucoid total protein and proteolytic activity of healthy or diseased fish. The acidifiers-contained diet because of potentially having synergistic effect caused inducing the mucus TIg. It seems that the orally use of Na difirmate in 0.2% of the diet separately or combined with citric acid, at least for 15 days, can improve the cutaneous mucus immunological indices that its result is an increase in the survival rate of farmed rainbow trout.

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This study was conducted from April 2017 to June 2018 in a Trout aquaculture farm in Firoozkoh, Tehran province, to distinguish environmental and managerial risk factors affecting incidence of viral diseases in the fish farm under study. Averaged visit from fish farm was 2 times a month and all biosecurity measures were advised and applied during every visit. Some of the physico-chemical parameters were recorded daily. Samples from all cargoes of eyed-eggs imported from abroad and also from larvae after active swimming and absorption of yolk sac were taken for RT-PCR test. Virology, bacteriology, parasitology and mycology tests in the farm and authorized laboratory were done. Clinical observations, macroscopic and microscopic examinations, checking all the sanitarian and productional managerial factors, also checking all the physical and chemical factors affecting the outbreak of viral diseases were done. During clinical observation of fishes, these symptoms were observed; anorexia, gathering at the raceway’s side and outlet, cachexia, one and two side exophthalmia, melanosis, integument ulcers, hemorrhage in ventricular and ocular areas, petechia in ventricular area, fecal casts, high mortality and also presence of a large number of moribund fishes. The result of the laboratory examinations was IHN positive of Rainbow trout fries. This disease caused about 80% mortality of the fries produced from the imported eyed-eggs cargo. The other fatalities with different reasons were also recorded such as; the Lutra’s attack at nights, the farm’s personnel running amongst other farms and transferrin pathogens, the transportation vehicles not being proper disinfected while inter to and exit from the farm and the severe food intoxication of fries. Regarding the results of this study, instruction of scientific and practical models has presented to decrease the effect of environmental and managerial risk factors in the incidence of the disease.

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