Search Results (654)

The gut microbiome of rainbow trout plays a crucial role in fish nutrition, immune function and stress resistance, making it a key factor in aquaculture sustainability. This review systematizes metagenomic data that enable the distinction between resident and transient microbial communities and the identification of a core microbiome. At the phylum level, the core is predominantly composed of Bacillota, Pseudomonadota, Actinomycetota, Bacteroidota, and Mycoplasmatota, with additional phyla detected depending on the gut region and methodological approach. Diet-induced changes are often rapid and reversible: insect meal and certain probiotics increase the abundance of beneficial Bacillota and suppress opportunists. Unlike dietary shifts, chronic stressors—particularly elevated temperatures and antibiotic treatment—can override these benefits, causing a persistent alpha diversity reduction, overgrowth of Pseudomonadata, and depletion of key commensals. The autochthonous mucosal microbial community is more resilient to short-term fluctuations but can be irreversibly altered by prolonged stress or antimicrobial therapy, leading to dysbiosis and reduced colonization resistance. A holistic understanding of host–microbe–environment interactions is essential for establishing dynamic reference ranges for a “healthy” microbiome. Such knowledge would enable early detection of dysbiosis and support the rational development of functional feeds and probiotics in commercial trout farming. Full article

Saline and alkali aquaculture offers a sustainable strategy to alleviate pressure on freshwater resources and ecologically ameliorate saline and alkali environments; however, information regarding the quality of aquatic products from such conditions remains scarce. This study evaluated the nutritional components, color, texture, and flavor profiles of grass carp cultured under three representative saline and alkali conditions in China: carbonate (CB), chloride (CR), and sulfate (SF), with a freshwater-cultured grass carp (Ctenopharyngodon idellus) serving as a control (CK). The results obtained in our study showed that the CB group exhibited the lowest muscle water content (68.96 ± 0.04%). Crude fat and sodium levels were significantly elevated in all treatment groups compared to the CK group (p < 0.05). Conversely, the CK group displayed superior springiness and higher concentrations of geosmin, adenine, and uracil. Notably, the CR group exhibited the highest L* and whiteness values, whereas the CB and SF groups possessed significantly higher collagen content and enriched EPA and DHA levels. These findings demonstrate that saline and alkali conditions distinctly modulate the nutritional and flavor profiles of grass carp, highlighting their potential for producing value-added aquatic products under saline and alkali conditions. Full article

Hydropower regulation can alter riverine habitats and potentially influence fish diet, gut microbiota, and nutritional characteristics. In this study, upstream and downstream populations of Hemibagrus guttatus (H. guttatus) were investigated in a dam-regulated reach of the Hongshui River associated with the Datengxia Water Conservancy Project using 12S rRNA and COI metabarcoding, 16S rRNA gene sequencing, and muscle nutritional analyses. Fish from the two habitats exhibited distinct dietary compositions, accompanied by significant differences in gut microbial diversity, community structure, and predicted microbial functions. Upstream fish harbored higher microbial diversity and greater abundances of Firmicutes-associated taxa, including several putatively beneficial bacteria, whereas downstream fish showed enrichment of Proteobacteria-associated taxa and functions related to environmental adaptation. Muscle composition also differed between habitats, with upstream fish containing higher moisture and crude lipid contents and downstream fish exhibiting higher crude protein content. These habitat-associated differences suggest that natural dietary resources and intestinal microbiota are closely linked to host nutritional characteristics. These findings highlight the importance of considering upstream–downstream habitat origin when evaluating the trophic, microbial, and nutritional characteristics of H. guttatus and provide a biological reference for the management and conservation of fish populations in dam-regulated rivers. Full article

Lauric acid (LA), a medium-chain fatty acid abundant in coconut oil and Hermetia illucens larvae, has been reported to promote growth performance and exhibit antimicrobial and immunostimulatory properties. This review examines current studies on its effects on growth performance, intestinal health, microbiota modulation, and immune responses in aquatic species. Studies in finfish and crustaceans were evaluated according to the LA source, distinguishing purified LA, LA derivatives such as monoglycerides, and LA rich ingredients, when considering LA rich ingredients. Overall, LA was associated with changes in growth performance, feed efficiency, survival, intestinal morphology, gut microbiota, and immune and antioxidant responses, although effects varied with source, dose, species, and experimental conditions. Reported effects include increased villus height and goblet cell density, modulation of gut microbiota, altered cytokine expression, increased antioxidant enzyme activity, and reduced lipid peroxidation. Overall, LA appears to be a promising functional component in aquafeeds for finfish and crustacean species. Nevertheless, inconsistent experimental designs, differences in LA sources, and species-specific responses make direct comparisons among studies difficult. Further studies that use standardized experimental protocols, including consistent LA sources, dietary inclusion levels, trial durations and evaluation criteria, are needed to define optimal inclusion levels in different aquatic species. Full article

Red coloring determines the commercial value of blood parrot cichlids (Vieja melanurus × Amphilophus citrinellus). While synthetic astaxanthin (SA) is commonly used to improve hue, its expensive cost has prompted the quest for more sustainable alternatives. This 60-day study looked at shrimp waste extract (SWE) as a dietary supplement for color improvement. Fish were assigned to five diets: basal control (G1, 0 mg/kg SA: 0 mg/kg SWE), SWE alone (G2, 0 mg/kg SA: 7.7 mg/kg SWE), high SA (G3, 90 mg/kg SA: 0 mg/kg SWE), moderate SA (G4, 45 mg/kg SA: 0 mg/kg SWE), and mixed SA with SWE (G5, 45 mg/kg SA: 7.7 mg/kg SWE). Growth and CIELAB skin pigmentation were evaluated. Growth performance was consistent across all treatments. Colorimetric study found that while the SWE alone (G2) significantly improved pigmentation compared to the control, it was less effective than the high-SA diet. However, incorporating SWE into the moderate-SA diet (G5) resulted in a promising complementary response. Despite having half the SA concentration, G5 achieved pigmentation that was comparable or superior to the G3 diet by the end of the feeding trial. These data revealed that, while SWE has lower independent activity, it is an effective complementary additive for shortening the feeding period required to achieve a similar redness. Finally, SWE enables the partial substitution of synthetic astaxanthin, providing a cost-effective and environmentally sustainable nutritional strategy for the ornamental aquaculture business. Full article

Several global challenges are converging: rising organic solid waste generation, growing food demand, and increasingly unfavorable conditions for food production, including more frequent and severe droughts, water scarcity, and limited agricultural land for expansion. Bioconverting organic waste into alternative protein sources has emerged as a promising strategy to address waste management and feed production challenges simultaneously. This study presents a comprehensive systematic literature review on protein production through the bioconversion of residual biomass using the black soldier fly (BSF, Hermetia illucens). The BSF is a highly voracious organism during its larval stage and can substantially reduce organic waste volumes while converting them into biomass rich in proteins and lipids with high nutritional value for livestock and aquaculture feed formulations. The review examines Waste-to-Protein systems from three perspectives: technical, economic, and environmental. The technical perspective focuses on production system operations and substrate properties. The economic perspective addresses profitability indicators, capital and operating costs, economies of scale, and the economic performance of incorporating insect-derived protein into animal production systems. From an environmental perspective, Life Cycle Assessment (LCA) is the predominant method for evaluating WtP-BSF systems. Among the systems assessed using LCA, 63% rely on crop-derived substrates for larval feeding. These substrates have intrinsic commercial value, and together with the environmental burdens associated with energy consumption during BSFL rearing, they may constrain the overall sustainability and profitability of WtP-BSF systems. By evaluating factors such as feed dosage, larval density, actual organic waste, and eco-efficiency metrics for livestock feed, opportunities for a circular economy could be developed in developing countries, helping to decrease dependence on landfills. Full article

Population growth in urban food systems has led to a decline in food resources and the emergence of social imbalances, while consumers’ shift toward a healthy and sustainable lifestyle, against the backdrop of a growing carbon footprint and negative health impacts, highlights the need to promote fish-based products as part of a balanced diet, alongside the implementation of circular strategies for utilizing byproducts from processing, which has led to increased interest in reformulating these products in accordance with the principles of the circular bioeconomy. Aquaculture and the agri-food industry generate a large amount of byproducts that are underutilized, even though they could be extremely useful as functional food ingredients. Recycling these streams into ingredients is an effective way to reduce food waste, make better use of resources, and lessen the environmental impact of food systems. In this context, by-products can be strategically incorporated into food reformulation processes, where their bioactive compounds simultaneously improve both the nutritional value and the technological function of foods. However, such approaches can only be effectively utilized if there is a coordinated framework that ensures food safety, supports scalable processing technologies, and complies with regulatory standards. This analysis takes an integrated approach to examine how specific processing strategies, quality control measures, and risk assessment protocols can work together to ensure nutritional optimization, guarantee food safety, and promote circular use. This paper also addresses how these interconnected systems contribute to maintaining public health and increasing consumer confidence, particularly in urban food systems. By highlighting these connections, the research offers a clearer operational perspective on applying circular economy principles to sustainable food production. Even with these opportunities, issues related to scalability, regulatory compliance, and the limited number of applied studies remain major challenges. In this context, this paper examines how the coordinated implementation of these mechanisms can contribute to public health, strengthen consumer confidence, and facilitate the transition to sustainable urban food systems. Finally, this paper offers a clearer operational perspective on how the principles of the circular economy can be effectively put into practice by harmonizing nutrition, safety, and value-added recovery. Full article

The production performance, muscle quality, and gut microbiota of aquatic animals are closely associated with host growth stage and disease status. This study therefore compared the gut health, antioxidant capacity, and muscle nutritional composition of greenhouse-cultured Pelodiscus sinensis covering two growth stages (juvenile and adult) and two physiological states (healthy and diseased). The results showed that healthy turtles possessed significantly longer and denser intestinal villi compared with diseased turtles (p < 0.01), and adult turtles maintained higher activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and lysozyme (LZM) than juveniles regardless of health condition. Digestive enzyme profiles varied with age and health. Compared with adult turtles, juveniles exhibited significantly higher trypsin activity in both healthy and diseased groups (p < 0.001). Conversely, juveniles displayed significantly lower lipase activity than adults in the diseased group (p = 0.008). For muscle nutritional composition, adults contained higher crude protein (CP), essential amino acids (EAAs), and umami amino acids (UAAs) than juveniles, while healthy turtles had significantly better muscle quality indices than diseased individuals (p < 0.05). Meanwhile, gut microbial composition differed significantly between growth stages and health states (p = 0.001). The relative abundance of unclassified_f_Lachnospiraceae and Clostridium_sensu_stricto_2 was positively correlated with GSH-Px and muscle nutritional composition indicators (CP, EAAs, and UAAs), whereas it was negatively correlated with liver alkaline phosphatase (ALP), acid phosphatase (ACP), and intestinal enzyme activities. Data also showed that unclassified_o_Bacteroidales and unclassified_f_Lachnospiraceae may affect muscle nutritional composition and non-specific immunity by regulating the microbial functional pathways of amino acid metabolism, the digestive system, and non-specific immunity system. Collectively, these observations offer insights into variations in physiological traits of greenhouse-cultured P. sinensis. These correlational findings suggest that gut microbiota are closely associated with muscle nutrition and antioxidant status, providing valuable insights for sustainable soft-shelled turtle aquaculture. Full article

Background/Objectives: This study presents a gas chromatography–mass spectrometry (GC–MS) method for the derivatization-free quantification of the three major short-chain fatty acids (SCFAs)—acetate, propionate, and butyrate—in gilthead sea bream (Sparus aurata) fecal samples. SCFAs are key metabolites involved in intestinal physiology and are widely recognized as indicators of gut microbiota activity and host health across animal species. In aquaculture research, SCFA profiling can provide valuable insight into diet–microbiota interactions and gut functional status. Methods: The method was developed and optimized using gut-content samples collected from 105 gilthead sea bream at the end of two independent feeding trials, yielding 42 pooled samples (18 from FT1 and 24 from FT2). An extraction protocol based on acidified aqueous extraction with water followed by liquid–liquid extraction using methyl tert-butyl ether was developed (ExA) and subsequently optimized (ExB) to improve extraction consistency and efficiency. SCFA separation and quantification were performed by GC–MS using external calibration. Method validation included evaluation of linearity, matrix effects, and partition coefficients between water and methyl tert-butyl ether. Results: The optimized extraction method (ExB) demonstrated high analytical performance, with linearity coefficients exceeding 0.992 and matrix effects below 17.4%. Conclusions: The proposed method represents a practical and reliable approach for routine SCFA analysis in fish fecal samples. It provides a useful analytical tool for studies investigating diet–microbiota interactions, gut health, and functional responses to nutritional interventions in aquaculture species. Full article

The rapid expansion of global aquaculture and increasing demand for sustainable protein sources have intensified the search for alternatives to conventional fish meal. Wolffia globosa, the smallest and fastest-growing flowering plant, has emerged as a promising yet underutilized aquatic resource with significant potential in aquaculture nutrition and sustainable food systems. Despite growing interest in aquatic plant-based proteins, comprehensive evaluation of W. globosa across nutrition, cultivation, and application systems remains limited. This review synthesizes current knowledge on its biology, nutritional composition, functional properties, and application potential in aquaculture and circular bioeconomy systems. W. globosa exhibits rapid vegetative propagation, high biomass productivity, and minimal resource requirements, enabling efficient cultivation in nutrient-rich environments. It contains high-quality protein (20–48% dry weight), essential amino acids, polyunsaturated fatty acids, dietary fiber, vitamins, minerals, and diverse bioactive compounds with antioxidant and immunomodulatory properties. Feeding studies demonstrate its potential to enhance growth performance, feed efficiency, and physiological health in aquatic species. Additionally, its capacity to absorb nitrogen and phosphorus supports nutrient recycling and water quality improvement in integrated aquaculture systems. However, variability in nutrient composition, limited large-scale cultivation data, insufficient long-term feeding trials, and uncertain economic feasibility at industrial scale remain key challenges for its commercial adoption. Overall, W. globosa represents a promising but still developing biomass resource with strong potential to reduce dependence on fish meal while supporting environmentally efficient aquaculture and future food systems. Future research should focus on optimizing cultivation practices, developing efficient processing technologies, and validating long-term feeding performance to facilitate its large-scale adoption. Full article

European seabass (Dicentrarchus labrax) hematology is widely used in nutrition, welfare, stress and health studies, yet results from different laboratories are often difficult to compare. This critical narrative review examines how preanalytical handling, analytical procedure and biological context affect that comparability. It is written for researchers, diagnostic laboratories and aquaculture health teams that collect or use D. labrax blood data. Primary European seabass studies are discussed directly where they provide quantitative operating conditions, method comparisons or measurable biological changes. Manual microscopy, automated analyzers and flow cytometry are considered separately because nucleated erythrocytes and thrombocytes create different sources of error in each approach. The review distinguishes practical quality-control checks from the fuller reporting required for reproducibility and separates published operating conditions from numerical limits that have not been validated for the species. Seasonal studies show large coordinated shifts in red blood cell count (RBC), hemoglobin concentration (Hb) and hematocrit (Hct), whereas white blood cell count (WBC) and thrombocyte results remain particularly dependent on cell definition and analytical method. Published pooled estimates are useful for broad comparison but not as universal diagnostic limits. The most defensible use of European seabass hematology is therefore within a defined population, a stated sampling protocol and a method whose performance is known for the intended measurement. Full article

The Siberian sturgeon (Acipenser baerii, Brandt, 1869) is a potamodromous freshwater species with major ecological and commercial importance. Natural populations across the main Siberian River basins have declined so severely that the species is now classified as Critically Endangered on the IUCN Red List. This narrative analysis synthesizes current scientific knowledge regarding the ecology, reproductive biology, conservation status, and nutritional value of products derived from A. baerii, with the aim of providing an integrated perspective on this species, which has recently been introduced into Romanian aquaculture and occupies the interface between biodiversity and human consumption needs. The species’ remarkable ecological and morphological plasticity, which underlies its wide natural distribution in the Ob, Irtysh, Yenisei, and Lena River basins, has also made it the dominant species in global sturgeon aquaculture, commercially farmed in Europe, Asia, and South America. Reproductive management in farming systems relies on hormonal induction, non-invasive maturity assessment, and controlled hatchery practices, while emerging no-kill technologies enable repeated caviar harvesting without sacrificing the female, improving both ethical standards and economic efficiency. From a nutritional standpoint, A. baerii yields two high-value products: caviar, a rich source of the long-chain polyunsaturated fatty acids EPA and DHA, whose dietary intake has been associated with cardiovascular and neurodevelopmental benefits in the broader nutrition literature, and meat, characterized by high-biological-value protein, a favorable amino acid profile, and significant omega-3 content. By-products such as skin, swim bladders, glands, and cartilage contribute to the higher-value utilization of the species within the circular bioeconomy. Still, notable gaps remain in genetics and sex determination methods, in early life behavioral ecology, and in cryopreservation protocols. Future work should also look at more sustainable feed formulations and new value-added products. Full article

Yeast (Saccharomyces cerevisiae) and its various fractions are assessed as sustainable functional feed additives that address both nutritional requirements and health challenges in intensive aquaculture systems. This review is based upon existing knowledge of yeast-derived products, critically evaluating their applications within aquafeeds. Specifically, it explores the use of whole yeast, yeast cell walls, autolysates, hydrolysates, and individual bioactive compounds. The main emphasis is placed on the yeast products containing β-glucans, mannanoligosaccharides (MOS), nucleotides, and other bioactive compounds, which provide significant advantages for enhancing innate and adaptive immunity, thus modulating gene expression, and raising antioxidant responses across diverse aquaculture species. We state the optimal inclusion levels from the scientific literature, which may range from as low as 0.1% for whole yeast products and about 0.4% for specific fractions, though species-specific responses vary considerably. Furthermore, this review integrates some of these areas to present a cohesive overview of different mechanisms of action, species-specific applications, physiological impacts on the gut, and related organ and systemic health. We also note specific haematological parameters and disease resistance across fish and crustacean species that may be affected by yeast products. By integrating the mechanistic insights with production-oriented application, this review fills the knowledge gap by establishing a framework for the powerful nature of yeast’s multiple roles in aquaculture nutrition. It serves to scope the potential future of commercial technologies leading to novel yeasts as functional feed additives. Although the literature suggests potential benefits for growth, immunity, antioxidant status, and gut health, the magnitude of response is highly variable amongst investigations. Full article

Copepods are widely recognized as biologically superior live prey for many marine fish larvae, yet their routine large-scale production remains a major bottleneck in aquaculture. Within this context, the harpacticoid genus Tigriopus has attracted increasing attention because it combines broad environmental tolerance, ease of culture, and promising nutritional and biotechnological value. This review critically examines the current state of knowledge on the genus Tigriopus, with particular emphasis on its aquaculture relevance, while integrating the biological, ecological and ecotoxicological framework needed to interpret the specific case of the Mediterranean species T. fulvus. The available literature shows that in aquaculture, the potential of this copepod genus is supported by complementary evidence across species. T. californicus currently provides the strongest proof of concept for pilot-scale biomass production and biochemical valorization, particularly as a source of omega-3- and astaxanthin-rich biomass. T. japonicus contributes most clearly to culture optimization and live-feed application, especially with respect to feeding performance and stocking-density effects. Tigriopus fulvus, in contrast, remains an earlier-stage but credible Mediterranean candidate, showing promising diet-dependent naupliar production and survival, although its culture technology is still underdeveloped. Overall, Tigriopus should be regarded as a genus of growing relevance for aquaculture, not only as live prey but also as a potential source of functional biomass. Future progress will depend on improved mass-culture methods, feeding optimization, harvesting efficiency, and a comparative species-level framework linking biological traits to specific aquaculture applications. Full article

Frequent outbreaks of bacterial and fungal diseases in aquaculture cause severe economic losses, making biological control using probiotics a crucial strategy. Bacillus velezensis synthesizes diverse antimicrobial secondary metabolites; however, its biocontrol potential is tightly regulated by environmental signals such as cultivation time. In this study, we investigated the effect of growing time on the antifungal activity of B. velezensis GHZJ-1, isolated from an aquatic environment. It was found that GHZJ-1 shows obvious antifungal activity against the aquatic pathogen Metschnikowia bicuspidata upon 48 h growth but no such activity for 24 h via the agar-diffusion method. We further compared the transcriptomes of GHZJ-1 cells collected at 24 h and 48 h through RNA-Seq. Our results revealed that compared with 24 h, 1821 genes were differentially expressed at 48 h, with 903 upregulated and 918 downregulated. Downregulated genes were enriched in primary metabolic pathways (e.g., ribosome assembly and carbon metabolism), whereas upregulated genes were enriched in secondary metabolite biosynthesis and transmembrane transport. Importantly, 35 upregulated genes directly associated with antimicrobial activity were identified, notably including the ones encoding core elements of a large polyketide synthase (e.g., pksN, log₂FC = 2.24), the petrobactin siderophore system (highest log₂FC = 3.39), and various antimicrobial peptide export systems. Furthermore, the degU gene was activated at 48 h. These data suggest that facing continuously increased environmental stress over time, GHZJ-1 undergoes global transcriptional reprogramming and resource reallocation, downregulating basal metabolism to construct a synergistic antagonistic system coupling chemical defense with nutritional competition. This study elucidates the time-dependent mechanism for antifungal activity in GHZJ-1, providing a molecular theoretical basis for its green biocontrol application in aquaculture diseases caused by fungi. Full article