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Today, due to the high nutritional value of fish, consumers' interest in using ready-to-eat foods based on fish is increasing worldwide. However, due to the presence of high amounts of protein and polyunsaturated fatty acids, aquatic products are highly sensitive to oxidation and the growth of microorganisms. The purpose of this research was to investigate the possibility of delaying oxidative and microbial spoilage and maintaining the quality and safety of rainbow salmon burgers during the storage period in the refrigerator using nano-encapsulated peppermint essential oil. Peppermint essential oil was nanoencapsulated by using a combination of gum arabic and soy protein isolate. Then it was added to the fish burger formulation at the levels of 0, 0.05, 0.1 and 0.15%. The values of pH, total volatile nitrogen bases (TVN), peroxide indices (PV) and thiobarbituric acid (TBA), and total count of bacteria were tested during the 12-day storage period at 4°C. Particle size, PDI index, zeta potential and microencapsulation efficiency of peppermint essential oil nanocapsules were 297.4 nm, 0.328 nm, -32.17 mV and 87.24%, respectively. During the storage period, pH, TVB-N, PV and TBA values of burgers increased. Peppermint essential oil nanocapsules showed significant antioxidant and antimicrobial activity and reduced the rate of fat oxidation and bacterial growth in fish burgers. There was a positive correlation between the concentration of essential oil nanocapsules and its antioxidant and antimicrobial activity. The greatest effect of inhibiting the growth of bacteria and reducing the rate of oxidation of fats was observed in the burger containing 0.15% nanocapsules. The results of this research suggest the use of peppermint essential oil nanocapsules at a concentration of 0.15% in order to maintain quality, reduce the rate of oxidation and microbial spoilage in fish burgers. [ABSTRACT FROM AUTHOR]

The diversity of O-polysaccharides (O-antigens) among 28 Aeromonas salmonicida strains isolated from ill fish has been determined by using high-resolution magic angle spinning (HR MAS) NMR spectroscopy. The new O-polysaccharide has been identified in two isolates. This new structure was investigated by 1H and 13C NMR spectroscopy and matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The following structure of the linear hexasaccharide repeating unit of A. salmonicida O-antigen has been established: →3)-α-L-Rhap-(1→3)-α-D-ManpNAc-(1→2)-β-D-Glcp-(1→3)-α-L-Rhap2OAc4OAc-(1→3)-β-D-ManpNAc-(1→3)-α-D-Glcp-(1→. This new A. salmonicida O-polysaccharide was detected among two isolates collected from trout and turbot fish in 2010 and 2011, respectively. Further investigations should be conducted to evaluate the distribution of this new O-polysaccharide among a larger collection of isolates, depending on their geographic origin, the species of fish, and the health status of the fish. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the changes in the quality of rainbow trout (Oncorhynchus mykiss) meatballs cooked with the sous-vide technique. Vacuum-packaged fishball were cooked using the sous-vide method under two different temperature (60 °C and 80ºC) and two different times (15 and 20 minute) and stored at 4±1ºC for 25 days. The results showed that sous vide cooking technique at 80 °C for 20 min. effectively limited bacterial growth. It was determined that sous vide cooking technology significantly reduced the levels of total volatile base nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS) at the end of storage. As the cooking temperature increased, the pH values of the meatball samples also increased. According to the sensory evaluation results, the meatballs cooked with the sous vide technique received higher scores than the control group, and the most preferred cooking temperature and time was determined to be 60ºC for 20 minutes. [ABSTRACT FROM AUTHOR]

Introgression of non‐native conspecifics changes the genetic composition of wild populations, potentially leading to loss of local adaptations and fitness declines. However, long‐term data from wild populations are still relatively few. Here, we studied the effects of introgression in a Danish brown trout (Salmo trutta, L.) population, subjected to intensive stocking with domesticated hatchery fish of non‐native origin. We used wild‐caught genetically wild and admixed trout as well as fish from the partly domesticated hatchery strain used for stocking the river up until ~15 years prior to this study, to produce 22 families varying in hatchery/wild admixture. Following a replicated common‐garden experiment conducted in fish tanks from first feeding through 23 weeks at 7, 12, and 16°C, we observed a significant positive relationship between family admixture and fish size upon termination, an effect observed through all levels of admixture. Furthermore, the admixture effect was most distinct at the higher rearing temperatures. Although the hatchery strain used for stocking had been in culture for ~7 generations, it had not been deliberately selected for increased growth. These data thus demonstrate: (i) that growth had increased in the hatchery strain even in the absence of deliberate directional selection for this trait, (ii) that the increasing effect of admixture by temperature could represent inadvertent selection for performance in the hatchery strain at higher temperatures, and most significantly, (iii) that despite undergoing up to five generations of natural selection in the admixed wild population, the genetically increased growth potential was still detectable and thus persistent. Our findings suggest that altered growth patterns and potentially their cascading effects are of importance to the severity of hatchery/wild introgression, especially under changing‐climate scenarios and are of general significance to conservation practitioners seeking to evaluate long‐term effects of intra‐specific hybridization including under recovery. [ABSTRACT FROM AUTHOR]

Background: Obsessive-Compulsive Disorder (OCD) is a type of anxiety disorder that is marked by intrusive and distressing thoughts, as well as repetitive behaviors. Trout fish (Oncorhynchus mykiss) is a functional food that might have potential therapeutic effects on many neurological disorders including OCD. Objective: This study aims to explore the effects of Al-Assi River trout fish meal, a dietary source of tryptophan, on obsessive-compulsive disorder (OCD) symptoms and related molecular pathways in BALB/c mice. Methods: OCD mice were divided into five groups: one control group without any treatment, one group treated with fluoxetine (a selective serotonin reuptake inhibitor), and three groups fed with different doses of trout fish meal (0, 7.5, and 15 g/kg body weight). The mice were subjected to various behavioral tests, such as the marble test, tail suspension test, sucrose preference test, and forced swim test, to evaluate OCD and depressive-like behaviors. Moreover, the expression and protein levels of genes involved in the serotonergic and GABAergic systems were measured. Results: The results indicated that trout fish meal had dose-dependent effects on OCD-like behaviors, revealing exacerbation at lower doses and improvement at higher doses. For instance, in the marble test, OCD mice fed with 7.5 g of trout fish/kg body weight buried more marbles than those fed with 15 g/kg of trout fish (4.5 vs 3.33 out of 6, p>0.05). In the tail suspension test, the immobility time of OCD mice treated with fluoxetine was numerically lower than that of the untreated OCD mice (63.6 vs 87.3 seconds, p>0.05). Furthermore, normal mice had different baseline gene expression profiles than OCD mice. Normal mice had the highest fold increase of Gabra gene expression (3.75) compared to the untreated OCD group, followed by groups treated with 7.5 and 15 g of trout fish/kg body weight (2.02 and 1.44, respectively). Conclusions: This study suggests that dietary interventions rich in tryptophan, such as trout fish meal, may have modulatory effects on OCD symptoms and molecular mechanisms in mice. However, the optimal dosing and individual variability need to be considered. More research is required to clarify the underlying mechanisms and to evaluate the potential efficacy of trout fish meal in treating OCD in humans. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) as one of the world's most pressing public health problems needs immediate attention, because it has the ability to affect the human healthcare, agriculture, and veterinary industries. Despite warnings about overuse and their implications, antimicrobials are overprescribed worldwide for humans and animals, which leads to the promotion of resistant microorganisms such as bacteria. Food is a medium for exposure to or transfer of residues of the drugs and can contribute to the burden of the pharmaceuticals associated with development of AMR. Studying on residues of veterinary drugs in foods is essential in the fight against AMR. Herein, we introduce a new method for visualizing the residues of a veterinary drug in animal matrices using radionuclides, called "Depletion Imaging". Amoxicillin was chosen to be the first antimicrobial for this study. The drug was labeled with [62Zn/65Zn] ZnCl2. Radiolabelled amoxicillin and non-labeled amoxicillin were administrated to rainbow trout fish simultaneously. To enable visualization of the remaining residues of amoxicillin in fish, In-vivo positron emission tomography (PET) imaging was done at different intervals from 30 min to 21 days after administration. Evaluation of the amount of radiolabelled amoxicillin in fish was done using a high purity germanium (HPGe) nuclear detector, and enzyme linked immunosorbent assay (ELISA) technique was used for the non-labeled drug. In this study, a comprehensive method for in-house production of zinc radioisotopes was also included. The results showed that depletion imaging and biodistribution study based on gamma spectroscopy of radionuclides in tissues, is a precise method for accurate understanding of the drug's distribution, metabolic and excretory profile. [ABSTRACT FROM AUTHOR]

Simple Summary: Antibiotics have become a threat to aquaculture due to their negative impact on aquatic environments, fish, and consumers. To contribute to the research and creation of novel tools that are able to treat and control disease in fish and substitute the use of antibiotics in the aquaculture industry, this study investigates the impact of postbiotics added through feed on health parameters and disease resistance in rainbow trout. After 30 days of supplementation with postbiotics, an improvement in survival rate when facing an experimental infection with the causative agent of Red Mouth Disease was observed in rainbow trout. This research illustrates, for the first time, the positive effect of postbiotic supplementation on rainbow trout survival when challenged with Red Mouth Disease infection; in summary, this proves the suitability of the postbiotic product for the aquaculture industry and its relevance regarding the current efforts to reduce and replace the utilization of antibiotics in animal husbandry. Postbiotics are innovative tools in animal husbandry, providing eco-friendly solutions for disease management within the industry. In this study, a new postbiotic product was evaluated for its impact on the health of rainbow trout (Oncorhynchus mykiss). In vivo studies were conducted to assess the safety of the Weissella cibaria strains used in postbiotic production. Additionally, this study evaluated the impact of diet supplementation with 0.50% postbiotics on growth performance during a 30-day feeding trial; the gut microbial communities, immunomodulation, and protection against Yersinia ruckeri infection were evaluated. The strains did not harm the animals during the 20-day observation period. Furthermore, the effect of postbiotics on growth performance was not significant (p < 0.05). The treated group showed a significant increase in acid-lactic bacteria on the 30th day of the feeding trial, with counts of 3.42 ± 0.21 log CFU/mL. Additionally, there was an up-regulation of the pro-inflammatory cytokine IL-1β in head kidney samples after 48 h of feed supplementation, whereas cytokines IL-10, IL-8, INF-γ, and TNF-α were down-regulated. The findings indicate that rainbow trout fed with postbiotics saw an improvement in their survival rate against Y. ruckeri, with a 20.66% survival improvement in the treated group. This study proves that incorporating postbiotics from two strains of W. cibaria previously isolated from rainbow trout into the diet of fish has immunomodulatory effects, enhances intestinal microbial composition, and improves fish resistance against Y. ruckeri. [ABSTRACT FROM AUTHOR]

Italy is one of the main European producers of trout fish, and the most important producing area is the Autonomous Province of Trento (APT) in the North East. The objective of the study was to obtain a snapshot of the trout farms of the APT by identifying biosecurity factors, objectifying them, and classifying the establishments accordingly. Data from 62 salmonid farms were collected using a national checklist in which biosecurity elements were identified and assessed using the method of expert elicitation. The purpose was to evaluate the levels of biosecurity of a trout farm in order to rank the risk of introduction and spread of infectious fish diseases. The main critical factors identified during this study were as following: (i) cleaning and disinfection of the cargo truck; (ii) regular collection, storage, and disposal of dead fish; (iii) presence of anti-bird nets; (iv) use of dedicated equipment for the different sectors of the farm; and (v) presence of external areas dedicated to the loading of dead fish. [ABSTRACT FROM AUTHOR]

The study aims to analyze the chemical composition of Suaeda aegyptiaca essential oil (PSAE) by GC–MS, produce the nanoemulsified essential oil (NSAE) using ultrasound, and compare the antimicrobial and antioxidant activity of the PSAE and NSAE in laboratory medium and rainbow trout fish (Oncorhynchus mykiss). Geranyl‐acetone (30.52%) and p‐Vinylguaiacol (10.66%), and (e)‐β‐ionone (7.79%) were the main PSAE chemical compounds. The mean droplet size diameter, polydispersity index, and viscosity of NSAE were 179.67 nm, 0.255, and 0.96 cP, respectively. PSAE and NSAE showed a moderate antiradical potential against DPPH‐ and ABTS‐free radicals (50 < IC50 < 250 μg mL−1). There was no significant difference between antiradical scavenging of PSAE and NSAE (p >.05). E. faecalis and K. pneumonia were the most and lowest sensitive bacteria to PSAE and NSAE, respectively. Examining different treatments on the shelf‐life of minced fish showed that Kakol essential oil could improve the shelf‐life of fish between 12.5% and 60% (depending on quality index). There was no significant difference between the bioactivity of PSAE and NSAE, which means that the nanoemulsion showed acceptable performance at lower essential oil concentrations. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in surface water is widespread throughout the world as a result of numerous anthropogenic activities and geo-genic mechanisms. This contamination is also affecting aquatic life, as fish have the potential to acquire heavy metals in their tissues making them vulnerable. Worldwide lakes are an important source of water for the inhabitants of the area. So, in the present study, we have focused on the Satpara Lake to check the extent of heavy metal pollution and their accumulation in fish to provide baseline data for metal pollution management. Samples were collected from three locations (inflow, center, and outflow sites) during two seasons (summer and winter). Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to analyze heavy metals concentration. Among the metals, Cd, Pb, As, and Fe revealed relatively higher concentrations. The highest concentration of heavy metal found in water and fish was of Cd, i.e., 8.87 mg L−1 and 18.19 mg L−1 in summer season, respectively. Arsenic concentration was also higher than the permissible limits in both water (0.76) and fish (1.17 mg L−1). The water quality assessment showed that in the summer season, the HPI (heavy metal pollution index) value 253.01 was more than 100, indicating the bad quality of water for drinking purposes. However, the HPI value 35.72 was less than 100 in winter. Toxicity hazard calculation of fish in summer seasons gives Hi values greater than 10.0, indicating the acute effect on human health as compared to winter. [ABSTRACT FROM AUTHOR]

The extent and availability of suitable habitat is a fundamental factor limiting the abundance of natural populations. In many stream ecosystems, habitat degradation has reduced habitat quality by removing critical habitat features such as pools. We hypothesized that adding pool habitat to streams would increase habitat quality for salmonid fish and improve population productivity. In this study, we used instream structures to add pool habitat to four headwater streams and estimated changes to habitat quality for cutthroat trout (Oncorhynchus clarkii) across two seasons using a bioenergetic model. Fish populations were monitored over 5 years to evaluate how treatments influenced fish abundance and growth. We found that the proportion of suitable habitat was higher in treatment sections and in artificially created pool habitats. Abundance of young-of-the-year trout was higher in treatment reaches in comparison to controls and the growth of trout across all size classes sampled was higher in treatment reaches. Our results indicate that increasing pool habitat improves habitat quality resulting in increased densities of cutthroat trout and higher fish growth. [ABSTRACT FROM AUTHOR]

The effect of microwave power levels on the drying attributes of Trout fish (Oncorhynchus mykiss) in a microwave dryer was investigated in this study. Microwave power level of 450 W was used to dry 20 g of fish samples. The moisture ratio of fish during drying was calculated, and the data obtained were applied to 18 well known thin-layer mathematical models of drying. Model constants and coefficients were calculated by nonlinear regression techniques. All the models were validated using statistical parameters, namely: Coefficient of determination (R²), Root Mean Square Error (RMSE), Chi-square (χ²), and Standard Sum of Error (SSE). The Aghbashlo et al. model was found to be the most appropriate in describing microwave drying behaviour of fish samples. The effective diffusivity was calculated using the Fick's diffusion equation, and the value was 22.62 x 10-7 m²/s. [ABSTRACT FROM AUTHOR]

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