Marine Fish Research Articles

BackgroundNervous necrosis virus (NNV) is a bipartite positive-sense RNA virus that causes viral nervous necrosis disease in larval and juvenile marine fish. In its genome, the RNA1 segment encodes RNA-dependent RNA polymerase (RdRp) for viral RNA synthesis, while RNA2 encodes coat protein for viral particle assembly. In addition, an RNA1-derived subgenomic RNA3 region encodes the non-structural B2 protein, which antagonizes host RNA interference mechanisms. However, the mechanisms of RNA3 transcription remain unclear.MethodsA DNA-based reverse genetic platform vector (pCMV-DRz) for recombinant (r) giant grouper (GG) NNV recovery was constructed. End sequences of GGNNV RNAs were determined by 5’ rapid amplification of cDNA ends (RACE) and/or circular RNA sequencing approach. Replication and transcription of viral RNAs in GGNNV-infected or mutant clones transfected grouper brain (GB) cells were detected by Northern blotting using anti-sense RNA DIG-labeling probes. Recombinant viral proteins were detected by using Western blotting or immunocytochemistry staining after GB cells transfected with pCMV-DRz-RNA1 or infected with rGGNNV. In addition, the viral kinetics of rGGNNV was determined using TCID50 assay. Finally, the minimum free energy secondary RNA structures were predicted using RNA-Fold of Vienna RNA Websuite.ResultsIn the reverse genetic platform, high viral titer of rGGNNV (108 TCID50/mL) was readily obtained from culture medium of pCMV-DRz-RNA1 and pCMV-DRz-RNA2 co-transfected GB cells, and the resulting genomic sequences at the viral 5′- and 3′-ends were confirmed to be accurate. The pCMV-DRz-RNA1 autonomous replicon alone (encodes RdRp) was sufficient to replicate RNA1 and produce RNA3. Without altering the encoded RdRp amino acid sequence, we performed mutagenesis of the RNA1 sequence and found that RNA3 is produced by a premature termination mechanism that involves an 8-base paired helix formed by a long-distance intragenomic RNA-RNA interaction. Furthermore, transcriptional promoter elements near the RNA3 negative-strand 3′-end also contributed to RNA1 and RNA3 production, and the expression levels of RNA1 and RNA3 were modulated by RNA2 co-expression.ConclusionOur results suggest that NNV utilizes premature termination mechanism for subgenome RNA3 transcription and NNV RNAs expression is coordinately regulated by viral cis- and trans-RNA sequences.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12985-025-02797-5.

BackgroundNervous necrosis virus (NNV) is a bipartite positive-sense RNA virus that causes piscine viral nervous necrosis disease in larvae and juvenile marine fish. Although NNV has been studied for decades, the translational mechanisms underlying its propagation remain unclear.MethodsThe molecular mechanism of NNV translation was investigated using grouper brain (GB) cell line infected with giant grouper (GG) NNV strain. Bromouridine and puromycin labelling were used to detect newly synthesized viral RNAs and proteins in viral factories (VFs), respectively. In addition, immunocytochemical staining, Western blotting and RNA fluorescence in situ hybridization (FISH) following densitometry and statistical analyses were employed to determine the involvement of cellular components during viral mRNA translation in infected control/inhibitor treated cells. Viral particles in remodeled microtubule-organizing center (MTOC) were analyzed using transmission electron microscopy.ResultsIn this study, we found that upon infection, newly synthesized NNV RNAs and replication intermediates colocalized with mitochondria. Meanwhile, the positive-sense mRNAs of RNA1 and RNA2 produced in mitochondria gradually moved toward the perinuclear area. Colocalization of the neo-synthesized proteins with RNA2 and coat protein suggested that viral translation proceeded at VFs within particular compartments in the cytoplasm. The phosphorylated eukaryotic initiation factor, p-eIF4E and its binding protein, p-eIF4E-BP, also colocalized with RNA2 and coat protein in VFs, suggesting that free eIF4E was recruited by the 5’-cap of RNA2 to initiate coat protein translation. Moreover, the initiation of coat protein translation by phosphorylation of eIF4E at Ser209 was further confirmed by upregulation of p-MNK1 and its upstream kinase p-p38. We also found that ribosomal protein RPS6 strongly colocalized with coat protein in VFs, but its phosphorylated form, p-RPS6, and its catalytic kinase (p-p70S6K) were gradually degraded after infection. A remodeled MTOC constructed by γ-Tubulin, Vimentin, Plectin and trans-Golgi was observed and acts as compartment for coat protein synthesis and virion assembly.ConclusionOur results suggest that NNV coat protein translation is initiated by p-eIF4E in VFs for 5’-cap viral RNA2 recognition, binding and later virion assembly by coat protein in the remodeled MTOC.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12985-025-02799-3.

A 56-year (1960 to 2015) catch data of Nigerian marine fisheries was analysed, and an ARIMA (3,1,3) model was employed to generate a short-term forecast (2016–2045). The Akaike information criterion (AIC), Schwarz information criterion (SIC), and Hannan-Quinn criterion (HQC) in conjunction with the log likelihood (Log L) and R2 statistics were employed to select the optimal model for the time series. Similarly, three benchmarks were considered: Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Theil Inequality Coefficient (TIC) to compare the in-sample and out–of–sample forecasts' performances of the estimated ARIMA (3,1,3) model, evaluating its forecasting ability and determining which forecast is superior for the model. The forecast results indicated that, everything remaining equal, approximately 27,021,461 metric tons of marine fish will be caught in Nigeria between 2016 and 2045 with an annual average of 900,715 metric tons. Temporal pattern of the forecasted data exhibited inherent fluctuations and an upward trend, similar to the original data. These fluctuations in catch trends are attributed to various factors, such as government policy, piracy, illegal activities of foreign trawlers, war conflicts, and the remote location of fishing villages. To obtain robust and reliable data from Nigerian marine fisheries, the negative impacts of these factors must be mitigated.

Humans are exposed to microplastics (MP) via ingesting contaminated fish, with a potential to cause adverse health effects such as oxidative stress, cytotoxicity, immunotoxicity, genotoxicity, and reproductive toxicity. To our knowledge, this is the first report of microplastics in edible muscles of commercially traded marine fish in Pakistan. Pampus argenteus and Otolithes ruber were purchased from the fish market, and the entire gastrointestinal tract (GIT) and a small portion of muscle of P. argenteus and O. ruber were digested, filtered, dried and observed under a stereomicroscope to detect MPs in the laboratory. Fourier Transform Infrared analysis was performed to determine chemical composition. All GIT samples and 50% of the muscle samples had MPs; a total of 46 MPs were isolated. The predominant shape of MPs detected was fibers (76%), the predominant color was black (48%), and polymer types included polyamide (33.4%), polyethylene (11.1%), and polyethylene terephthalate (22.2%), which can be sourced back to the textile and packaging industry. This pilot study reports the microplastic contamination in the GIT and muscles of P. argenteus and O. ruber, thereby raising a food safety concern. Future studies are needed to assess the risk associated with MP exposure via ingesting contaminated fish and associated adverse health effects, which will set the ground for risk communication and risk mitigation.

The diversity and complexity of Arctic fish communities increases as boreal species expand their range poleward in response to changing environmental conditions. In turn, borealization of fish communities modifies the species composition of Arctic food webs, trophic interactions, and distribution of contaminants. Contaminants in marine fish and how they vary as a function of feeding ecology and location in Arctic and boreal regions is lacking. Here we assessed the drivers of total mercury (THg) and organochlorine pesticides (OCPs) concentrations in boreal capelin (Mallotus villosus), glacier lanternfish (Benthosema glaciale), Greenland halibut (Reinhardtius hippoglossoides), blue hake (Antimora rostrata), and abyssal grenadier (Coryphaenoides armatus) from the northwest Atlantic and eastern Canadian Arctic. We also examined regional differences in THg concentrations in Arctic cod (Boreogadus saida) across the Canadian Arctic. Length/δ15N and species were the most important determinants of THg concentrations in all fishes, with habitat (δ13C and δ34S) also playing a small role. While most OCPs varied by species, only three varied positively by trophic position (ie, ΣParlar, ΣDDT, and Dieldrin), and one varied by location (ie Dieldrin). Generally, demersal fishes had higher Hg and OCP concentrations than pelagic fishes. Mercury concentrations in Arctic cod were higher in the western than the eastern Canadian Arctic, likely due to increased atmospheric inputs in the Beaufort Sea. Given the likely shift to pelagic systems and the replacement of Arctic residents with less contaminated boreal species (e.g. Arctic cod to capelin), we expect Hg to decrease in Arctic food webs with borealization. In contrast, since OCPs did not vary between Arctic and boreal species, we expect little influence of borealization on OCP concentrations in Arctic fishes.

Understanding the effects of environmental temperature on marine fish larvae is crucial for optimizing feeding regimes and promoting optimal development and growth from a zootechnical perspective in aquaculture practices. The present study investigated the impact of different rearing temperatures on development, growth, and oxygen consumption rates of Totoaba macdonaldi larvae. An open-flow seawater recirculating system was used in which larvae (150 specimens/L) were exposed in triplicate to four rearing temperatures (20, 24, 26, and 28°C) for 24days under standard larval rearing conditions. Larvae were sampled at 7, 12, 16, 20, and 24days post hatching (DPH) to assess growth performance, survival, histological condition, and respirometry. At the end of the trial, the highest total length (TL) and body weight (BW) values were observed at 26°C, with larvae displaying negative allometric growth in terms of TL and BW, similar to those reared at 24 and 28°C. In contrast, larvae reared at 20°C showed lower growth and an isometric growth pattern. No significant differences in Fulton's condition factor (K) were detected among treatments. Survival rates were the highest at 28°C, while increased cannibalism at 26°C was associated with elevated specific growth rates and thermal growth coefficients. Histological analysis revealed better structural organization in the gills and liver of larvae reared at 26°C, whereas other treatments showed signs of inflammation. Respirometry results indicated that larvae reared at 20°C had significantly higher metabolic rates. However, these differences diminished by DPH 20 and 24, likely reflecting developmental changes and phenotypic plasticity during the larval-to-juvenile transition. Based on physiological and metabolic indicators, a rearing temperature of 26°C is recommended for T. macdonaldi larviculture.

Gut microbiota can be shaped by host-related (e.g., species, diet) and environmental (e.g., habitat, geography) factors. Gut microbiota of the herbivorous fish family Kyphosidae vary between individuals and gut sections and can be influenced by diet and geography. Temperate Kyphosus sydneyanus are abundant on rocky reefs of northeastern New Zealand, where adults mainly consume Phaeophyceae, whereas juveniles typically feed on Rhodophyta and Chlorophyceae. We compared the gut microbiota of K. sydneyanus adults and juveniles to investigate the relative effects of ontogeny versus diet on bacterial community composition. We used 16S rRNA gene amplicon sequencing and ddPCR quantification to determine the following: (i) ontogenetic variation in gut microbiota of K. sydneyanus, (ii) shared microbial taxa, and (iii) processes influencing bacterial community assembly, given the lack of vertical transmission. To further explore dietary effects, we also compared these data to the gut microbiota of adult K. sectatrix, which are rare tropical vagrants to northeastern New Zealand. Juvenile K. sydneyanus exhibited greater dietary similarity to K. sectatrix adults than conspecific adults. Overall, K. sydneyanus gut microbiota diversity increased with fish size, and K. sydneyanus adults had a more diverse gut microbiota than K. sectatrix adults. Estimated absolute abundances and community structure varied considerably across individuals. K. sydneyanus juveniles had relative abundances more similar to those from adult K. sectatrix than adult conspecifics. However, a comparison of amplicon sequence variants (ASVs) showed that juveniles of K. sydneyanus shared more ASVs with conspecific adults. This suggests that historical contingency and selection are important drivers of community assembly.IMPORTANCEMost marine animals undergo external fertilization (e.g., fish) and lack mechanisms for vertical transmission of gut microbiota. Consequently, host-related and environmental factors can play important roles in community assembly. The gut microbiota of the herbivorous marine fish family Kyphosidae varies between individual fish, host species, diet, and geographic location. Juvenile Kyphosus sydneyanus shared more dietary similarity with adult K. sectatrix than adult conspecifics. Comparing gut communities of juvenile and adult K. sydneyanus and adult K. sectatrix collected from the same locations differentiates some of the causal factors involved in bacterial community assembly. Results suggest that the host diet has a strong influence on bacterial diversity and composition. In addition, historical contingency and environmental selection play a significant role in shaping gut microbiota through host ontogeny.

BACKGROUND. Osteoarthritis (OA) is a major medical and social problem in modern society, as it is the leading cause of impaired mobility, loss of independence, and disability. Sarcopenia, which often coexists with OA, minimizes the effectiveness of non-pharmacological treatment programs for osteoarthritis. There is considerable clinical interest in the efficacy of symptomatic slow-acting drugs (disease-modifying agents), focused on the clinical manifestations of sarcopenia.OBJECTIVE. To evaluate changes in muscle strength and function during therapy with a bioactive concentrate derived from small marine fish in patients with chronic nonspecific musculoskeletal pain and probable sarcopenia.MATERIALS AND METHODS. A single-center, open-label, prospective, phase IV comparative post-marketing study was designed to assess changes in muscle strength and function during treatment with a bioactive concentrate derived from small marine fish in 60 geriatric patients with probable sarcopenia and chronic nonspecific musculoskeletal pain.RESULTS AND DISCUSSION. During therapy, an increase in muscle strength was observed in both the intervention and control groups. Handgrip strength increased by 44.3 % over 2 months in the intervention group (from 14.7 kg to 21.2 kg), compared with a 5.9 % increase in the control group. Over the observation period, «Timed Up and Go» decreased by 40.6 % in the intervention, with most patients reaching the reference value compared to a 22.9 % reduction in the control. Gait speed increased by 6.5 % in the first month versus 2.4 % in the second month in the intervention. Pain reduction reached 83.1 % in the group after 2 months, compared to 22.8 % in the control (p = 0.02).CONCLUSION. The inclusion of a bioactive concentrate from small marine fish in the comprehensive management of pain exacerbations in patients with chronic nonspecific musculoskeletal pain and probable sarcopenia resulted in a greater reduction in pain compared to the control group. Under pain control conditions, indicators of muscle strength were significantly improved in the group receiving the bioactive concentrate compared to those in the control group.

The gut microbiome influences host behaviour through the gut–brain axis (GBA), a bidirectional network of signalling pathways. Although the GBA has been well studied in humans and other mammals, its role in shaping individual behavioural variation in fish remains largely unexplored. In this study, standardized behavioural tests were conducted on 67 juvenile gilthead seabream (Sparus aurata), consisting of 30 wild and 37 reared individuals, across five major behavioural axes—boldness, aggressiveness, sociability, activity and exploration—to determine their behavioural types using linear mixed models. High levels of repeatability of behaviour and consistent behavioural types were observed along the five studied axes. Gut samples from contrasting behavioural types were analysed for diversity, composition and structure using 16S rRNA sequencing. Statistically significant correlations and differences were found between wild and reared groups in both behavioural types and gut microbiome characteristics. These findings provide novel evidence of associations between behavioural types and the gut microbiome in juvenile marine fish, suggesting that gut microbiome may play a role in modulating fish behaviour. While this relationship could involve GBA interactions, further research is needed to confirm such mechanisms. This work could have translational significance for understanding survival, recruitment and life-history evolution in the early life stages of wild fish, as well as improving conservation management of species in both aquaculture and their natural habitats.

Simple SummaryThe health of farmed marine fish, including the Japanese flounder (Paralichthys olivaceus), is severely compromised by temperature fluctuations and infections such as Edwardsiella tarda, resulting in significant economic losses. A previous study revealed that elevated temperature enhanced E. tarda dissemination in flounder tissues. However, the underlying mechanism has not been fully explained, especially the changes in protein level. This study utilized label-free proteomics to investigate the immune response of flounder to E. tarda infection under low (15 °C) and high (23 °C) temperature conditions. Multiple differentially abundant proteins (DAPs) were identified in each group. GO and KEGG analyses highlighted immune-related pathways and proteins, with key DAPs forming extensive interaction networks. Venn analysis revealed distinct responses: high temperature promoted endocytosis and complement activation, while low temperature increased histone levels and impaired RNA transport. These results enhance our understanding of how water temperature changes affect antibacterial immunity in fish.Fluctuating water temperatures and bacterial pathogens such as Edwardsiella tarda pose a serious threat to mariculture, resulting in significant economic losses within the flounder industry. A previous study revealed that elevated temperature enhanced E. tarda dissemination in flounder tissues. However, the underlying mechanism has not been fully explained, especially the changes in protein level. In this study, label-free proteomics was utilized to investigate the impact of high temperature (23 °C) and low temperature (15 °C) on flounder immune response to E. tarda infection. Our results identified 317 differentially abundant proteins (DAPs) in the low-temperature group (LI-LC) and 302 DAPs in the high-temperature group (HI-HC). GO and KEGG analyses of DAPs revealed numerous immune-related proteins and pathways. Twenty-six key DAPs in the LI-LC group and twenty-seven key DAPs in the HI-HC group were further identified and formed extensive interaction networks, respectively. Through the analysis of key immune-related DAPs that were specifically identified in both groups via Venn diagram analysis, we demonstrated that the endocytosis capacity and complement activity were enhanced in the HI-HC group, while histone abundance and RNA transport function were, respectively, increased and severely interfered with in the LI-LC group. These findings highlight a clear divergence in the immune response of flounder to E. tarda infection between 15 °C and 23 °C, providing valuable insights into how temperature variation influences antibacterial immunity in fish.

Biogenic amines (BAs) are key chemical indicators of fish spoilage and potential food safety hazards. This study investigated the formation of four common BAs-histamine, cadaverine, putrescine, and tyramine-and monitored microbial populations in Asian seabass (Lates calcarifer) and short-bodied mackerel (Rastrelliger brachysoma) stored at 0°C and 4°C for 7 days. Total viable bacteria, staphylococci, and Enterobacteriaceae were enumerated using culture-based methods, while BA concentrations were quantified by high-performance liquid chromatography (HPLC). The results revealed that microbial growth was significantly higher (p<0.05) in both fish species stored at 4°C when compared with those stored at ice temperature (0°C). The counts of total viable bacteria, staphylococci, and Enterobacteriaceae of short-bodied mackerel stored at 4°C reached 5.32-6.47 Log CFU/g after 7 days. Histamine levels in short-bodied mackerel stored at 4°C reached 292.67±1.53mg/kg by day 7, exceeding the Codex safety limit of 200mg/kg. Cadaverine, putrescine, and tyramine levels were also increased to 615.00±1.00, 461.67±1.53, and 731.67±1.53mg/kg, respectively. In contrast, histamine remained undetectable in Asian seabass under the same storage conditions. However, cadaverine, putrescine, and tyramine were detected in Asian seabass at 17.67±1.53, 17.00±2.65, and 8.33±2.08mg/kg, respectively. These findings provide essential reference data for assessing spoilage in marine fish species commonly consumed in Thailand and highlight the need for strengthened seafood safety standards on histamine. They further emphasize the critical role of effective cold chain management in traditional markets and local distribution systems.

ABSTRACT Objective Invasive carp, a name encompassing Black Carp Mylopharyngodon piceus, Silver Carp Hypophthalmichthys molitrix, Bighead Carp H. nobilis, and Grass Carp Ctenopharyngodon idella, are outcompeting native fish and causing environmental instability in the lower Mississippi River basin. Harvest by commercial fishers is the most cost-effective management strategy. However, low demand and dockside prices have reduced incentives for commercial fishers to target invasive carp, reducing annual harvest numbers. Currently, the aquaculture industry relies on fish meal and fish oil from marine fish species, such as Atlantic Menhaden Brevoortia tyrannus, as important ingredients for many diets. However, as the industry continues to grow, demand for these marine fish will surpass availability. Methods In this study, we assessed the performance of invasive carp fish meal (ICFM) and invasive carp fish oil (ICFO) as feed ingredients for Channel Catfish Ictalurus punctatus. Graded levels of ICFM and ICFO (Aquatic Protein LLC, Beardstown, Illinois) were incorporated into starter diets. The diets were formulated on a 35% crude protein, 6% fat basis and designed to meet the amino acid requirements of Channel Catfish. In two 8-week feeding trials, ICFM was used to replace Atlantic Menhaden fish meal (MFM) or all plant and animal protein sources (MFM, soybean meal, corn protein concentrate; trial 1) and ICFO was used to replace 50% or 100% of the Atlantic Menhaden fish oil (trial 2). During these feeding trials, triplicate tanks of Channel Catfish were fed one of six treatment diets and growth, feed intake, feed efficiency, proximate composition, and protein and energy retention efficiency were assessed. Terminal measurements were also used to calculate values for condition factor, viscerosomatic index, and muscle ratio. Results There were no significant differences in the growth performance or composition of Channel Catfish when ICFM was included as up to 47% of the diet dry weight. Replacing plant and animal protein with ICFM enhanced energy retention efficiency relative to a diet where ICFM replaced only MFM. Similarly, growth performance was maintained when ICFO was used in place of 100% of MFM. This suggests that ICFM and ICFO are suitable alternative ingredients in Channel Catfish starter diets. Conclusions Invasive carp products offer suitable ingredient alternatives that can be used in starter diets for farmed Channel Catfish. This has the potential to enhance market demand for invasive carp, thereby benefiting fisheries and local economies, improving conservation and invasive species management in the Mississippi River basin, and enhancing the overall sustainability of aquaculture.

The increasing reliance on imported fish products in Kazakhstan raises concerns about the presence of fish-borne parasitic infections, particularly zoonotic helminths that pose risks to public health. This study aimed to assess the diversity and prevalence of helminths in commercially imported marine fish using both traditional and molecular diagnostic methods. A total of 670 specimens representing 17 fish species were collected from retail markets in Astana, Almaty, and Karaganda. Macroscopic inspection and muscle compression techniques were used to detect larval parasites, followed by DNA extraction and PCR amplification targeting the ITS-2, 5.8S, 18S rRNA, and mitochondrial COX gene regions. Sequencing and phylogenetic analysis confirmed the presence of cestodes (Eubothrium crassum, Hepatoxylon trichiuri, Nybelinia surmenicola), acanthocephalans (Echinorhynchus gadi), and nematodes, with a predominance of zoonotic species from the Anisakidae family, including Anisakis simplex, A. pegreffii, Pseudoterranova decipiens, and Contracaecum osculatum. The highest levels of infection were detected in Atka mackerel (97.1%), herring (96.0%), mackerel (92.0%), and blue whiting (88.1%), while the lowest rates were recorded in smelt (6.8%), flounder (10.2%), and haddock (16.0%). This is the first molecular-based survey of fish helminths in Kazakhstan and highlights the need to integrate genetic screening into food safety control systems to better protect consumers and improve parasite monitoring of imported seafood.

Adaptive differences in the thermal stabilities of enzyme structure and function play critical roles in establishing the thermal optima and limits of all organisms. Thus, understanding the mechanisms underlying these adaptations can yield insights into protein structure-function relationships, protein evolution, and the consequences of temperature shifts on species distributions. Past studies have suggested that only a small number of amino acid substitutions are needed for adaptive change, but whether similar sites in the sequence, which we term thermal adaptation-related sequence sites (TRSS), and similar changes in amino acid content at these TRSS occur across widely different taxa remains to be elucidated. For detecting TRSS among orthologs of species adapted to a wide range of temperatures, we investigated 277 lactate dehydrogenase-A (LDH-A) orthologs in marine fish from diverse habitats. We validated the importance of several TRSS variants using site-directed mutagenesis on zebrafish LDH-A, effectively recreating the variants in the zebrafish ortholog. Our results indicate that enzyme thermal adaptation arises primarily from a few substitutions that influence hydrophobicity in functionally important regions of secondary structures. These findings reveal striking convergence in the sites (the TRSS) of temperature-adaptive evolution of LDH-As and provide insights into the types of amino acid substitutions that foster adaptation to temperature. Furthermore, the patterns of convergent evolution identified in this study supported development of a deep learning model for predicting thermal limits. This model can provide an important tool for predicting thermal ranges of species and the potential effects of temperature change on distribution patterns.

This study reveals novel skeletal deformities in two marine fish species (Nemipterus randalli and Pomadasys stridens) from Antalya Bay, Türkiye, linking them to potential impacts on locomotion and ecological fitness. Major abnormalities include pectoral fin absence, saddleback syndrome, and nasal defects. This study establishes the critical relevance of documenting fish deformities as a powerful and sensitive tool for monitoring ecosystem health. The study advocates for integrating imaging technologies into ecological monitoring to detect hidden stressors affecting marine life. By understanding how deformities influence movement and survival, scientists can better evaluate anthropogenic impacts on fish populations. These insights advance the use of morphological abnormalities as sensitive indicators of ecosystem health, supporting more proactive marine conservation strategies.

The global marine aquarium hobby is a multibillion-dollar industry, largely driven by demand from the United States. Much of this trade occurs online. We web scraped 4 major US-based e-commerce platforms selling marine aquarium fish to determine the retail price and source (wild capture, aquaculture, or both) of 13 families of ray-finned marine fish (Actinopterygii). We supplemented this with ecological and economic trait data from FishBase and the International Union for Conservation of Nature (IUCN). Across all platforms and 13 popular fish taxonomic families, we found 734 unique species for sale, 89.2% (655 species) of which were sourced exclusively from the wild. A total of 45 species were of conservation concern (20 threatened species and 25 additional species with decreasing population trends), 38 of which were sourced solely from the wild. Retail price was significantly correlated with source, body length, minimum occupied depth, and schooling behavior. A further 100 species for sale were not listed as being in the aquarium trade in FishBase or by the IUCN, indicating incomplete information on this fishery in 2 important databases. For 58 species (encompassing 71 variants) with both wild-caught and captive-bred individuals for sale, aquaculture fish were a mean 28.1% (95% confidence interval 15.3) cheaper than their wild-caught counterparts.

The classification of Hysterothylacium larval types in the Aegen Sea (FAO fishing area 37.3.1) is incomplete and still requires further investigation. This study aimed to offer morphological identification, supported by entire ITS sequence data, of Hysterothylacium larval types infecting six out of sixteen commonly consumed marine fish species from the Aegean Sea: Boops boops, Trachurus mediterraneus, Spicara maena, Upeneus moluccensis, Engraulis encrasicolus, and Sardina pilchardus. This study describes three morphotypes IV, V, and VIII in the Aegean Sea for the first time using both morphological and genetic data. We also report Spicara maena as new hosts for larval morphotype V. Herein, the presence of potential zoonotic larval type VIII has been found in B. boops, E. encrasicolus, and S. pilchardus in the Aegean Sea, and may pose a public health risk.

Abstract Background The investigation of marine fish biodiversity has become fundamental for a reliable database supporting the conservation and sustainable use of marine resources. The east coast regions of India are found suitable for a diverse range of marine fish species. Understanding this biodiversity is necessary for both biological conservation and economic development. The objective of this present study is to assess the marine fish diversity and their nutritional insights across different zones of the east coast of India. Methods This review synthesizes information from various review and research papers regarding marine fish diversity and nutritional profiling of coastal regions in India. This analysis aimed to explore the evolution of scientific understanding and identify key contributors to the field of marine fish diversity. Results The eastern coastline of India, stretching from West Bengal to Tamil Nadu, hosts a diverse range of marine fish species due to its diverse climatic conditions, habitats, and ecological zones. This region is rich with commercially important species such as Indian mackerel, ribbonfish, tuna, snappers, sparidae, carangidae, pomacentridae, and clupeidae. Fish resources are a vital source of macronutrients and micronutrients. A total of 4752 marine fish species were recorded across four states, i.e. Odisha (2611), Tamil Nadu (1656 species), West Bengal (314), and Andhra Pradesh (171), reflecting the region's ecological richness across estuarine, mangrove, and coral reef habitats. Family-level diversity was particularly high in groups such as Carangidae, Mugilidae, and Pomacentridae. Nutritionally, several species including, Lates calcarifer, Scomberomorus commerson, Rachycentron canadum, and Trichiurus lepturus were identified as rich sources of omega-3 fatty acids, protein, vitamin D, calcium, selenium, and zinc. Small pelagic fish like, Indian mackerel and Indian anchovy are especially valuable for micronutrients, benefiting vulnerable populations such as children and pregnant women. These findings underscore the critical role of regional species in addressing nutritional security. However, conservation assessments reveal that while many species are listed as Least Concern, including Epinephelus fuscoguttatus and Harpadon nehereus face population declines. This study highlights the urgent need for integrated strategies promoting sustainable harvesting, nutritional profiling, and artificial propagation of key species, aligning biodiversity conservation with aquaculture development and long-term food security in the East Coast region of India. Conclusion The current reports highlight nutritionally valuable marine fish species rich in omega-3 fatty acids, proteins, Vitamin D, Selenium, and Zinc along East coast of India. Species such as Lates calcarifer and Scomberomorus commerson exhibit high potential for enhancing nutritional security. Their availability and suitability for aquaculture underscore the need for sustainable management to balance nutrition, biodiversity, and long-term marine resource use.

This study aims to assess the concentrations of heavy metals—iron (Fe), zinc (Zn), copper (Cu), and lead (Pb)—in six economically significant marine fish species: Sardinella aurita (sardine), Sphyraena sphyraena (barracuda), Epinephelus costae (dusky grouper), Pagellus erythrinus (common pandora), Scomber japonicus (chub mackerel), and Oblada melanura (saddled seabream). A total of 18 specimens from each species were obtained from local fishermen at the Tripoli fish market. The average lengths and weights were as follows: sardine (19.22 cm, 60.17 g), barracuda (32.35 cm, 122.5 g), dusky grouper (25.02 cm, 190.17 g), common pandora (20.55 cm, 119.5 g), chub mackerel (24.35 cm, 139.17 g), and addled seabream (20.5 cm, 181.67 g). Heavy metal concentrations were measured using Flame Atomic Absorption Spectroscopy (FAAS). Results indicated that all detected concentrations were within internationally accepted safety limits, as defined by WHO, FAO, and EU standards. Among the studied metals, iron exhibited the highest concentration across all species, followed by zinc. The highest iron levels were recorded in Pagellus erythrinus, followed by Sardinella aurita, Oblada melanura, Scomber japonicus, Sphyraena sphyraena, and the lowest in Epinephelus costae. Similarly, Pagellus erythrinus showed the highest copper concentration, followed by Sardinella aurita, Oblada melanura, Scomber japonicus, Sphyraena sphyraena, and Epinephelus costae. Lead concentrations were highest in Sardinella aurita, followed by Epinephelus costae, Pagellus erythrinus, Oblada melanura, Scomber japonicus, and lowest in Sphyraena sphyraena. These findings confirm the safety of the studied fish species for human consumption and provide a valuable reference for environmental monitoring and public health risk assessment in the region.

Natal homing in fish is a crucial phenomenon that shapes the ecology and evolution of populations. The homing behavior of fish has been well studied in several species. However, research has focused on a limited number of fish species due to methodological constraints, whereby the methods are either too expensive or there are too few suitable species to which they could be applied. We propose a scheme to optimize the ‘otolith edge’ concept, followed by the establishment of a discriminant model based on the optimized elemental fingerprints as natural markers. We take small yellow croaker Larimichthys polyactis (Bleeker, 1877) as an example. A 10-row by 3-column laser spot lattice on the otolith edge was identified as the optimal arrangement, and then spawning individuals from the same cohort were identified using the discriminant model. Homing rates of small yellow croakers were as follows: 86% in Haizhou Bay, 71% in Lvsi, 17% in Zhoushan, and 28% in Dachen. The results show that the otolith fingerprint as a natural marker is feasible for fish homing studies, but the application of otolith elemental fingerprints requires strictly quantitative evaluation.