To reduce catches of red king crab (Paralithodes camtschaticus) below the minimum legal size (MLS), it is mandatory to use four circular escape openings when conducting quota-regulated pot fishing in northern Norway. Despite this, substantial catches of individuals < MLS are still common. This can result in labour intensive sorting, injuries to crab and post-release mortality. This study evaluated whether increasing the number of escape openings improves size selectivity in king crab pots. Two field trials were conducted. An operational trial under commercial fishing conditions compared pots with four openings to pots with eight. A separate catch comparison trial to quantify size-dependent relative retention compared pots with one escape opening to pots with eight. Increasing the number of openings reduced capture and/or retention of crab < MLS in both trials. For the operational trial, pots with more openings caught significantly fewer crab < MLS, averaging 2.3 fewer individuals per pot. In the catch comparison trial, pots with multiple openings significantly reduced the catch of crab < MLS by approximately 33% – 46% relative to pots with a single opening. However, the reduction in retention for catches < MLS was not strongly size dependant, and substantial catches of crab < MLS still occurred in both trials. The capture of legal-size individuals was largely unaffected. Retention probability increased with overall catch size, suggesting the availability and therefore effectiveness of escape openings is limited at higher crab densities. Video observation suggested that openings can become blocked by other crab as catches increase. Together, the results demonstrate that increasing escape opening number can contribute towards reducing discarding and better animal welfare in the Norwegian king crab fishery. However, during periods of high abundance of crab < MLS on the fishing grounds, additional size selective measures are likely needed to further improve the sustainability of the fishery.
Climate change poses increasing challenges to inland aquaculture through rising temperatures, dissolved oxygen depletion, and heightened disease pressure. Genetic improvement of climate resilience has therefore become a priority for sustainable aquaculture production. This perspective paper synthesizes key concepts and methodologies for breeding climate-resilient aquaculture stocks, with a particular focus on giant freshwater prawn (Macrobrachium rosenbergii). We review the genetic basis of phenotypic plasticity, genotype-by-environment interaction, and reaction norms, highlighting their relevance for resilience breeding under dynamic environmental conditions. Using preliminary data from a breeding population in Thailand, which were considered a proof-of-concept and required validation in larger populations, we illustrate the application of reaction-norm models to quantify climate resilience traits and their genetic parameters. Finally, we discuss emerging genomic and omics-based approaches, including genomic selection and multi-omics integration, to enhance prediction accuracy and accelerate genetic gains for resilience. Collectively, this work provides a conceptual and practical framework for developing climate-resilient prawn stocks, supporting the broader adoption of data-driven breeding strategies in tropical aquaculture.
Nile tilapia (Oreochromis niloticus) is a major aquaculture species worldwide, yet the limited availability of high-quality seed remains a key constraint to improving production. This study aimed to evaluate the effectiveness and optimal dosage of Eleutherine bulbosa powder supplementation on reproductive performance of broodstock, growth performance, gut microbiota, and the resistance of resulting larvae to environmental stress and Aeromonas hydrophilaRf infection. Four dietary treatments were tested for 30 days: 6.25 g/kg feed (TA), 12.5 g/kg feed (TB), 25 g/kg feed (TC), and a control without supplementation (TD), each with three replicates. The resulting larvae were subsequently subjected to environmental stress and A. hydrophilaRf challenge at lethal concentration (LC50) and 107 CFU/mL. Results showed that hematological and biochemical data showed significant differences (P < 0.05) among treatments, including higher WBC, ALT, and AST in TC and TD. Antioxidant responses indicated increased SOD and GPx activity and decreased MDA in TA and TB. Reproductive parameters improved with supplementation, with higher (P < 0.05) estradiol-17β, vitellogenin, GSI, fecundity and histology analysis values in TA and TB compared with the control. E. bulbosa supplementation modulated intestinal microbiota composition by increasing OTU richness and the abundance of beneficial genera. Growth performance indicators (WGR, ADG, FCR) improved (P < 0.05) in TA and TB, while TC showed reduced performance compared with lower dosages. Larvae produced from treated broodstock exhibited significantly higher survival and lower A. hydrophilaRf counts (P < 0.05) than those from the control. These results identify 10.2–13.8 g/kg of feed as the optimal supplementation range for enhancing broodstock performance and larval fitness. However, further long-term studies are required to validate these findings across a complete reproductive cycle.
The downgrading of Atlantic salmon due to fillet quality traits, such as textural and compositional traits, cause high economic loss for the aquaculture industry. However, very few studies have investigated the heritability and genomic architecture of textural and compositional traits in fish. Therefore, the aims of this study were: 1) to provide insight into the heritability of sixteen quality metrics, such as gumminess, moisture, and glucidic traits, 2) to determine the correlation between these traits, and 3) to identify any genomic regions associated with variation of the phenotypes using 50K SNP array data. A total of 196 Saint John River strain North American Atlantic salmon from the 2011 year-class were harvested and the phenotypes recorded. Moderate genomic heritabilities (>0.2) were estimated in eight of the sixteen fillet quality traits, including moisture and fat. There were generally moderate to high correlations (0.16 to 0.98) between many of the quality traits implying that a change in one trait would likely impact some of the others. In particular, fat and glucose both had moderate heritability and moderate to high correlations to many other traits, implying they could possibly be used for selection to represent most traits evaluated in this study. Maturity and bled weight effects were significant for 13 traits, implying some of these quality traits may already be benefiting from selection pressures on growth and age traits that are currently in the breeding program. No significant loci were found to be associated with any of the traits. However, purge loss had a distinct peak that approached the significance threshold and passed the suggestive threshold. These results provide important baseline data on the genomic architecture of fillet quality traits in Atlantic salmon.
High-altitude aquatic ecosystems are experiencing rapid environmental change as climate warming accelerates faster in mountain regions than the global average. This review brings together current understanding of how these shifts influence fish through both direct environmental pressures and indirect ecological consequences. Rising temperatures, altered hydrological regimes, glacial retreat, and frequent extreme climatic events are altering the physical characteristics of high-altitude rivers and lakes. These changes disrupt thermal regimes, oxygen availability, flow patterns, and habitat connectivity, resulting in conditions that challenge the survival of coldwater fish. Beyond these immediate effects, climate change drives a set of indirect effects, including range shifts, altered migration behaviour, irregularities in reproductive timing, disease outbreaks, biodiversity loss, and changes in ecosystem functioning. The physio-phenological mechanisms that control fish responses to temperature variations and hydrological changes brought on by climate change in high-altitude settings are summarized in this review. Understanding these dynamics is crucial for managing cold-water fish populations, evaluating population resilience, and developing adaptive conservation plans in the face of rapidly warming world.
A 60-day feeding trial was conducted to evaluate the effects of partial replacement of fish meal by fermented cottonseed meal (FCSM) and to preliminarily assess whether dietary lysine supplementation could provide additional physiological benefits under this replacement condition in Litopenaeus vannamei (Pacific white shrimp) (initial body weight 2.55 ± 0.02 g). A total of eight isonitrogenous and isoenergetic experimental diets were formulated, including five diets containing graded levels of FCSM (0, 7.5%, 15%, 22.5%, and 30%) as partial substitutes for fish meal, and three lysine-supplemented diets containing 0.25%, 0.50%, and 0.75% crystalline lysine based on the diet with 7.5% FCSM. Growth performance tended to decrease with increasing FCSM inclusion, and the FCSM7.5 group showed the most favorable overall performance. Supplemental crystalline lysine did not further improve growth performance under this condition. Partial replacement of fish meal by FCSM altered the expression of hepatopancreatic apoptosis-related genes (CYC, Caspase-3, and AIF), suggesting potential activation of apoptosis-related signaling under certain replacement levels. Under the present experimental conditions, inclusion of 7.5% FCSM did not cause marked adverse effects on hepatopancreas health, although some antioxidant-related indices suggested altered physiological stress responses. Notably, crystalline lysine supplementation under the FCSM7.5 condition was associated with improved antioxidant-related responses and reduced histological signs of hepatopancreatic damage. These findings should be considered preliminary, because lysine supplementation was evaluated only under the FCSM7.5 dietary background and dietary amino acid profiles were not determined.
This study assessed the effects of different co-culturing densities of giant freshwater prawn (Macrobrachium rosenbergii) on water quality, growth performance, nutritional quality, economic benefits and intestinal microbiota of Chinese mitten crab (Eriocheir sinensis) ponds. For this purpose, we set three different co-culturing density groups, each with three replicates: 7.5 inds./m2 (LD), 15 inds./m2 (MD), 22.5 inds./m2 (HD). The stocking density of Chinese mitten crab (Eriocheir sinensis) was kept consistent in three groups, at 1.50 inds./m2. The results showed that there were no adverse effects on the water quality, growth and antioxidant of crabs in three groups. Regardless of sex, the contents of PUFA, C18:2, EPA in the MD group were the highest. The crude fat, crude protein and EAA/TAA ratio of female crabs in the MD group were higher than those of male crabs. This showed that crab in the MD group exhibited superior nutritional value and flavor quality. In terms of economic benefits that year, compared with other co-culturing densities, the crab pond in the MD group could produce higher output value and create additional benefits for farmers. In addition, the crab in the MD group exhibits a relatively higher abundance of Actinobacteria and lower Vibrio. This showed stronger immune regulation ability, which could effectively maintain the homeostasis of intestinal microbial community, so as to reduce the risk of diseases caused by microbial imbalance. This showed that the MD group altered the intestinal microbial community of crab. Considering the water quality, growth, antioxidant capacity, nutritional quality, economic benefits and intestinal microbiota, when the density of M. rosenbergii is 15 inds./m2, the nutrition value of crabs is better and it is suitable for crabs to be stocked in the cultivation system.
Tropical aquaculture accounts for more than a quarter of global production, yet the biomass culture of copepods as live feed has remained a major bottleneck. The demand for tropical copepods as live feed for fish, and shrimp larvae and juveniles is rapidly increasing in tropical hatcheries. However, most studies have focused on temperate to cold-adapted copepod species that may not be suitable for aquaculture in tropical regions. This paper comprehensively reviews the current development of tropical copepod culture and highlights key knowledge gaps, particularly in determining optimal food levels and rearing conditions for suitable species in five genera: Pseudodiaptomus, Acartia, Oithona, Apocyclops, and Tigriopus, especially under the interactive effects of climate change associated stressors. Across taxa, optimal food concentrations for adults generally fall within ∼400–800 μg C / L, while thermal responses are species-specific, with performance typically highest below ∼30–32 °C and declining rapidly at higher temperatures. Culture densities are often constrained to ≤400 adults/L for Pseudodiaptomus and up to ∼1000–3000 adults/L for tropical Acartia before negative density-dependent effects emerge. Climate change stressors, including warming, deoxygenation, and salinity fluctuations, can shift these thresholds, reducing biomass production and the stability of copepod harvests. Future research should focus on resolving species- and stage-specific environmental thresholds, elucidating metabolic and microbiome-mediated responses, and developing adaptive culture systems integrating real-time monitoring and predictive modelling to optimise copepod production under variable environmental conditions.
Oxidative stress is an important cause of hepatic injury in fish and is frequently associated with inflammation, apoptosis, and impairment of liver function. This study investigated the protective effects of glycyrrhizic acid (GA) against Concanavalin A (Con A)-induced oxidative liver injury in orange-spotted grouper (Epinephelus coioides) through both in vivo and in vitro experiments. In the in vivo trial, E. coioides were fed diets supplemented with 50-400 mg/kg GA for 8 weeks before intraperitoneal injection of Con A (2.5 mg/mL). Liver samples were collected 24 h after injection for biochemical and molecular analyses. The results showed that dietary GA at 50-200 mg/kg significantly reduced the hepatic expression of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), and alleviated inflammatory response and apoptosis (P < 0.05). In the in vitro experiment, GS cells were treated with GA at 0.025, 0.05, 0.1, and 0.2 mg/mL. Cell morphology was observed microscopically, cell viability was evaluated using the CCK-8 assay, and the expression of apoptosis-related genes (caspase-3 and caspase-8) and inflammatory genes (TNF-α, IL-1β, and IL-6) was determined by qRT-PCR. GA at 0.025-0.1 mg/mL significantly enhanced cell viability, reduced apoptosis, increased CAT and GSH activities, and reduced MDA levels (P < 0.05). Morphological observations further showed that GA effectively alleviated Con A-induced cellular damage. In conclusion, GA protects against Con A-induced oxidative liver injury by attenuating inflammatory response and apoptosis, providing a potential nutritional strategy for improving fish health.
Dissolved oxygen (DO) is a key factor in aquatic ecosystems, and its fluctuation—driven by climate change and human activity—poses increasing stress on marine organisms. Here, we investigated the mitochondrial responses of the sea cucumber Apostichopus japonicus to varying DO levels (7, 4, and 2 mg/L) using phenotypic, proteomic, and metabolomic analyses. Structural observations revealed increased cristae density at 4 mg/L and mitochondrial swelling and fragmentation at 2 mg/L. Hypoxic conditions reduced membrane potential and ATP production while increasing H2O2 levels. Mitochondrial copy number rose under moderate hypoxia but declined under severe hypoxia. Proteomic analysis (DIA-MS) identified 1307 and 2042 differentially expressed proteins in DO4 vs DO7 and DO2 vs DO7, respectively, which were enriched in pathways such as fatty acid metabolism and glycolysis. Metabolomic profiling (LC-MS/MS) detected 238 and 219 differential metabolites in the same comparisons, linked to sulfur and amino acid metabolism. Integrated analysis revealed that A. japonicus mitochondria adapt to hypoxia via a stepwise strategy involving quantity regulation, functional optimization, and quality control, which are achieved through modifications in mitochondrial dynamics, energy metabolism, oxidative stress, autophagy, and apoptosis. This study provides a valuable multi-omic dataset capturing mitochondrial responses to environmental oxygen variability in a non-model marine species. This comprehensive study lays a foundation for understanding the oxygen adaptation mechanisms of benthic echinoderms and facilitates broader molecular ecology research in the context of changing marine environmental conditions.
Black carp (Mylopharyngodon piceus) is an economically important freshwater aquaculture species in China, and improvement of growth traits is a major objective in its breeding. In a previous genome-wide association study (GWAS), nlrp3 was identified as a candidate gene for body weight and body length. In this study, we further analyzed genetic variation in the nlrp3 region and validated its association with growth traits in black carp. A discovery dataset of 537 black carp individuals retained from the previous GWAS cohort and an independent validation population of 275 additional individuals were analyzed for body weight (BW) and body length (BL). Linkage disequilibrium (LD) analysis identified 24 LD blocks in the coding region of nlrp3, and the GWAS lead SNP, Chr05_42410277, was located within the first prominent LD block containing six candidate SNPs. Local LD analysis showed strong linkage among these six SNPs, with most pairwise D′ values ranging from 0.99 to 1.00. In the discovery population, four SNPs showed significant associations with growth traits, and haplotype analysis identified eight common haplotypes, with clear haplotype-dependent differences in BW. In the validation population, four SNPs were polymorphic, and three of them were significantly associated with both BW and BL. In addition, the full-length cDNA of black carp nlrp3 was 3126 bp, encoding a protein of 1033 amino acids. Expression analysis showed that nlrp3 was expressed in all examined tissues, with significantly higher expression in the intestine and muscle, whereas significant differences between fast-growing and slow-growing individuals were observed only in the liver. This study provides further insight into the genetic basis of growth traits in black carp and suggests that variants in the nlrp3 region may serve as useful molecular markers for selective breeding.
Since 2019, a novel condition termed ‘emerging acute hemorrhagic syndrome’ (EAHS) has been associated with significant mortality in farmed Scophthalmus maximus L. (turbot) populations across China. Turbot circovirus (TurCV) has been identified as a primary pathogen associated with this syndrome, contributing to high mortality rates and severe economic impacts in intensive aquaculture operations. To address these challenges, the establishment of an early, rapid and reliable diagnostic approach is essential for effective EAHS management in turbot farming. In this study, we developed and validated a real-time recombinase polymerase amplification (RT-RPA) assay, alongside RPA combined with lateral flow dipsticks (RPA-LFD) and agarose gel electrophoresis (RPA-AGE), targeting the conserved region of the TurCV Capsid gene. Both methods enable visual detection within 15 min at a constant temperature ranging from 25 to 45 °C. Using a synthetic plasmid as a template, the RPA-LFD assay demonstrated a detection limit of 103 copies/μl. When evaluated with DNA extracted from EAHS-affected turbot, both assays exhibited an identical detection limit of 103 copies/μl. Specificity testing confirmed the absence of cross-reactivity with other common aquatic pathogens, including turbot reddish body iridovirus (TRBIV), Scophthalmus maximus reovirus (SMReV), hirame rhabdovirus (HRV), viral hemorrhagic septicemia virus (VHSV), lymphocystis disease virus (LCDV), Edwardsiella piscicida, Aeromonas salmonicida, Vibrio alginolyticus, Vibrio anguillarum, Pseudomonas plecoglossicida or DNA from healthy turbot. Field evaluations using clinical samples corroborated the assays' practical utility, with results aligning with conventional PCR and qPCR. Analysis of clinical specimens revealed that both assays accurately distinguished between positive and negative cases, with the RPA assay achieving a TurCV detection rate of 93.00% in clinical samples and a 97.07% concordance rate with conventional PCR. In conclusion, the RPA-LFD assay represents a simple, rapid, sensitive and cost-effective diagnostic tool for TurCV detection, offering significant promise for controlling EAHS outbreaks and reducing economic losses in turbot aquaculture.
This study evaluated the potential of fermented soybean meal (FSBM) as substitute for fishmeal-soybean meal mixture (1:2) in diets of yellow catfish (Pelteobagrus fulvidraco). FSBM was incorporated into the basal diet (180 g/kg fishmeal, 200 g/kg soybean meal) at levels of 60, 120, 180, and 240 g/kg by replacing the corresponding fishmeal-soybean meal mixture, thereby formulating five diets as the CON (control), FSBM-6, FSBM-12, FSBM-18 and FSBM-24 groups. Then, the above five diets were used to feed yellow catfish (16.70 ± 0.23 g) in recirculating system for 8 weeks. The growth performance evaluation revealed a marked increase in weight gain (WG) and feed intake (FI) for the FSBM-6 relative to the CON (P < 0.05). Serum total cholesterol (T-CHO) content, glutamate aminotransferase (AST) activity in the FSBM-6 group, and T-CHO, triglyceride (TG) content in the FSBM-12, FSBM-18, and FSBM-24 groups exhibited significant reductions in comparison with the CON (P < 0.05). Moreover, serum glucose (GLU) content, total antioxidant capacity (T-AOC),and alanine aminotransferase (ALT) activity were significantly depressed in the FSBM-24 relative to the CON (P < 0.05).The FSBM-6 and FSBM-12 groups displayed enhanced intestinal amylase activity relative to the CON (P < 0.05), and the FSBM-18 and FSBM-24 groups demonstrated decreased diamine oxidase activity, and trypsin activity in the FSBM-24 was also considerably diminished (P < 0.05). The FSBM-6 group showed a substantial elevation in anti-inflammatory factors (tgf-β and il-10), while the FSBM-12 group displayed a divergent response, with downregulated tnf-β and upregulated tgf-β (P < 0.05). In liver and gut histology, the FSBM-6, FSBM-12, and FSBM-24 groups showed significantly lower vacuolization rate of liver cell and higher muscularis thickness (MT) of intestine than the CON (P < 0.05). In gut microbiota profile, the FSBM-6 and FSBM-24 groups exhibited significantly higher Simpson index, abundance of Fusobacteriota, and Cetobacterium, but a markedly reduced abundance of Pseudomonadota relative to the CON (P < 0.05). Collectively, graded levels of FSBM (60-240 g/kg) improved serum biochemical indexes and intestinal health while growth performance was maintained, and the low replacement (60 g/kg) promoted the FI and WG of yellow catfish.
Long non-coding RNAs (lncRNAs), as emerging regulators of gene expression, serve as important regulatory factors of immune responses. Despite extensive research in mammals, its role in defence against pathogens in fish remains an area in urgent need of exploration. This study focuses on the regulation of innate immune responses by lncRNAs in fish. We identified a novel lncRNA LTCONS32135 in the Miichthys miiuy (miiuy croaker). This lncRNA exhibited significantly increased expression following LPS or Poly(I: C) stimulation, suggesting its potential for broad-spectrum immune responses. To explore its function, we demonstrated in the miiuy croaker and zebrafish (Danio rerio) infection model that overexpression of lncRNA LTCONS32135 effectively suppressed Vibrio anguillarum colonization and VSV viral replication, while simultaneously significantly enhancing the expression levels of pro-inflammatory cytokines (such as IL-6) and antiviral factors (such as ISG15), thereby positively regulating innate immunity and promoting the NF-κB and IRF3 pathway. In summary, lncRNA LTCONS32135 functions as a dual-immunity defence molecule within fish, positively regulating both antiviral and antibacterial responses. This discovery provides novel theoretical groundwork for understanding the innate immune mechanisms in fish.
Cold plasma (CP) is an eco-friendly, non-thermal technology attracting interest for seafood preservation and by-product valorization, yet its translation to crab processing remains limited. Crabs are high-value aquatic products, but their benthic lifestyle and intensive post-harvest handling elevate microbial risk, while shell-dominated by-products create substantial waste burdens. CP generates reactive oxygen and nitrogen species (RONS) that can inactivate microorganisms and may support greener processing of shell matrices; however, excessive RONS can accelerate lipid oxidation and protein modification, compromising quality. This review synthesizes advances relevant to crab processing, covering CP device configurations, RONS formation and delivery, and effects on microbial safety, oxidation/quality indices, sensory attributes, and shell-waste valorization. Distinct from general CP reviews, we organize the evidence around crab-specific matrices (meat/paste versus shell/by-products) and value-chain intervention points, including post-harvest handling and in-package decontamination, temporary culture/holding, and shell-waste processing. Where crab data are reported, we summarize quantitative endpoints for microbial reduction and oxidation/quality (e.g., peroxide value, TBARS, protein carbonyls, and color/texture) and describe parameter–response trends; where evidence is sparse, we clearly label mechanistic inference from broader aquatic-food studies. Finally, we discuss industrial translation by summarizing major scalability and cost drivers and by highlighting data gaps that currently limit techno-economic assessment. Future work should prioritize standardized reporting, pilot-scale validation, and optimization strategies that balance microbial safety with oxidation-sensitive quality.
Nervous necrosis virus (NNV) is an infectious pathogen, characterized by rapid infection and high mortality, and is commonly encountered in the aquaculture industry. There is an urgent need to develop effective antiviral agents against NNV to establish targeted therapeutic strategies and control viral spread, thereby reducing economic losses. Screening for potent antiviral compounds is critical for the development of highly effective anti-NNV drugs. In this study, a target-activatable detection probe (TAA-TNA1c) was constructed based on the previously screened aptamer TNA1c, which specifically recognizes NNV-infected cells. This probe was employed for high-throughput screening of anti-NNV compounds. The results demonstrated that TAA-TNA1c specifically recognized NNV-infected cells, with positive signals detectable as early as 6 h post-infection at a viral concentration of 0.2 μL/100 μL, indicating its ability to rapidly and efficiently identify NNV infection. Furthermore, antiviral drug screening using this probe yielded results consistent with those obtained by RT-qPCR. Notably, the entire screening process was completed within 2 h, highlighting the potential of TAA-TNA1c as a rapid screening probe for anti-NNV drugs. This study provides essential experimental data and a theoretical foundation for the development of antiviral therapeutics.Therefore, there is an urgent need to develop effective antiviral drugs against NNV, which is crucial for targeted treatment strategies, pathogen control, and loss reduction. Screening of effective antiviral active compounds, namely drug precursors, is key to developing highly efficient drugs against NNV. Reverse transcription-quantitative real-time PCR (RT-qPCR) is widely applied to screen and evaluate various substances to prevent and control virus infection. However, RT-qPCR is a cumbersome procedure and not suitable for high-throughput rapid screening. The aptamer TNA1c, which specifically binds to NNV-infected cells, was used to construct a target-driven activated aptamer probe (TAA). Then, the TAA probe was applied to establish a high-throughput screening (TAA-HTS) method for efficient evaluation of substances against NNV infection. TAA-HTS technology achieved rapid, sensitive, and specific screening of bioactive substances with significant anti-NNV effects. As compared to commonly used analytical methods, such as RT-qPCR, TAA-HTS has the advantages of easy operation and high sensitivity and specificity. The findings of this study provide data support and a theoretical basis for the development of effective antivirus preparations.
Licorice (Glycyrrhiza glabra) and ginger (Zingiber officinale) are phytogenic feed additives with well-documented antioxidant, antimicrobial, and immunostimulatory properties; however, their combined effects in grey mullet (Liza ramada) remain unexplored. This trial evaluated the individual and combined effects of these additives on growth, intestinal and hepatic health, antioxidant defense, immunity, and gut microbiota of L. ramada (n = 360, initial mean weight ± SE = 35.15 ± 0.26 g). A 60-day feeding trial was conducted with four dietary treatments (n = 3 replicates; 30 fish per replicate): basal diet (D1; control), licorice (4 g/kg; D2), ginger (10 g/kg; D3), or their combination (2 g/kg licorice + 5 g/kg ginger; D4). All diets were isonitrogenous (31.27 ± 0.19% crude protein) and isolipidic (8.50 ± 0.14% crude lipid). The combined supplementation (D4) significantly (P < 0.05) improved final body weight, weight gain percentage, specific growth rate, and feed conversion ratio compared to the control and single-supplemented groups. Gastrointestinal enzyme functions (lipase and protease) demonstrated significant enhancement in all supplemented groups compared to the control, with the most pronounced effects in D4. Histological analysis revealed increased intestinal villi length, surface area, and goblet cell count, alongside well-organized hepatic parenchyma and increased glycogen deposition in D4. Biochemical assessments showed elevated total protein and globulin levels with no adverse consequences on glucose or liver and kidney health signs. Dietary supplementation increased lysozyme level, inhibition of Streptococcus agalactiae, and nitroblue tetrazolium (NBT) reduction, with the combined group (D4) showing the maximum levels (P < 0.05). Antioxidant responses were superior in D4, with increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) capacities and reduced malondialdehyde (MDA) (P < 0.05). Furthermore, gut microbiota analysis demonstrated significant reductions in pathogenic bacteria (including Escherichia coli, Salmonella sp., Vibrio sp., and Staphylococcus sp.) and significant enhancement of acid-fermentative bacteria in all supplemented groups, with the most pronounced effects in D4. These findings underscore the potential of combining licorice (2 g/kg diet) and ginger (5 g/kg diet) as natural feed additives to promote mullet growth, health, and aquaculture sustainability.
Fish farming often experiences sudden outbreaks of bacterial pathogens that have significant negative effects on productivity and economics. Edwardsiella tarda is currently a significant aquaculture health concern that needs to be addressed with enhanced control and management strategies, as it affects both fresh- and saltwater fish, and can occasionally affect humans. The purpose of this review was to evaluate the impact of Edwardsiellosis, specifically caused by E. tarda, on tilapia farming. The review analysed the effects of disease outbreaks and their economic impacts on the industry, examining emerging methods of control and management, including preventative measures and innovative solutions, to encourage the adoption of comprehensive strategies that enhance the sustainability of aquaculture. Numerous studies have focused on the clinical, epidemiological, and pathological aspects of E. tarda infection in aquaculture over the years. Edwardsiellosis poses a major challenge for tilapia farming, particularly in regions such as Brazil, necessitating an integrated management approach based on prevention, sustainability, and collaboration among producers, researchers, and regulatory authorities. The economic impact of Edwardsiellosis on fish farming in Brazil and globally underscores the importance of implementing comprehensive control measures to safeguard the long-term viability of the sector. Prevention efforts primarily focus on management practices, but ongoing research is investigating alternative treatments such as vaccines, phytobiotics, and probiotics. Additional studies are needed to demonstrate the effectiveness of these alternatives in managing and treating Edwardsiellosis in aquaculture production environments, as well as their economic viability for widespread industrial application. Combining early surveillance, biosecurity, nutritional interventions, and sustainable therapies can help reduce disease outbreaks and reliance on antibiotics. Wider adoption requires validation under commercial conditions, standardised protocols, and supportive policies. Coordinated efforts are crucial to ensure sanitary effectiveness, economic viability, and the sustainable development of aquaculture. Given current global research trends, future approaches to addressing Edwardsiellosis should involve integrating natural feed additives with effective management practices to improve fish health, especially in regions where environmental conditions increase disease susceptibility.
The Fukushima nuclear wastewater discharge may shift global protein demand towards freshwater aquaculture due to seafood safety concerns. China, as the world's largest freshwater fish producer, is highly vulnerable to such a shift because of its critical dependence on imported marine fishmeal—a key component of aquafeed that provides essential protein and omega-3 fatty acids like DHA. This study reveals that while direct radioactive contamination of major fishmeal sourcing areas (e.g., Peru, Chile) is projected to be low, the primary threat stems from a supply chain disruption driven by market confidence and consumer risk perception triggering a “Not In My Backyard” (NIMBY) response, where consumers avoid seafood broadly as a precautionary measure. With over 70% of China's fishmeal consumption reliant on imports, such a disruption could significantly impact the nation's freshwater aquaculture output and food security. We propose that proactively developing strategies for the partial substitution of fishmeal with alternative protein sources (e.g., plant, insect, and microbial proteins), coupled with necessary DHA supplementation, is essential to enhance the resilience of China's aquaculture industry and ensure its sustainable growth.
