Marine Fish Research Articles

The large yellow croaker (Larimichthys crocea) is an economically important marine fish in China, whose growth rate in aquaculture has yet to meet the industry's demands. Understanding the mechanism underlying inter-individual growth differences will create a favorable condition for selective breeding. In combined transcriptome and metabolome analyses, this study collected muscle tissues from four groups of croakers categorized based on sex and growth rate: fast-growing males, slow-growing males, fast-growing females, and slow-growing females. We identified 2344 differentially expressed genes (DEGs) and 198 differentially expressed metabolites (DEMs). Three genes, bpgm, mstnb, and mylpfb, played a crucial role in the growth regulation of large yellow croaker. The pathway enrichment analysis showed that "Aminoacyl-tRNA biosynthesis", "Alanine, aspartate and glutamate metabolism", "Inositol phosphate metabolism" and "Retrograde endocannabinoid signaling" pathways were involved in growth regulation. This study provides new clues for future research on the molecular mechanisms of growth regulation in large yellow croaker and builds a theoretical basis for improving the growth quality of this species.

The complex association between nutritional status and sleep quality in older adults remains poorly understood. This review critically examines recent advances and the potential of targeted nutritional interventions to enhance sleep and promote healthy aging. Emerging evidence links malnutrition and imbalances in key micronutrients and macronutrients to poor sleep quality in older adults. Studies highlight that adherence to plant-based diets, adequate consumption of milk and marine fish, and avoidance of stimulants such as green tea and coffee are associated with better sleep outcomes. Supplementation with specific nutrients, including methyl donor nutrients and amino acid derivatives, shows promise in improving sleep parameters. Additionally, social determinants influencing nutritional status also impact sleep quality. However, the majority of current evidence is observational, and randomized controlled trials remain limited in size, duration, and focus, often examining isolated nutrients rather than comprehensive dietary patterns. Nutritional status is a modifiable factor that significantly influences sleep quality in older adults. While current findings support the potential of dietary and supplemental interventions to improve sleep, robust clinical trials and mechanistic research are needed to establish causality and optimize personalized nutrition strategies for healthy aging and better sleep health.

Clestobothrium Lühe, 1899 is a genus of cestodes belonging to the order Bothriocephalidea, which infects marine fish from the Gadiformes order. Herein, a novel species of Clestobothrium is described from the intestine of the European hake Merluccius merluccius (Linnaeus, 1758) in the Ionian Sea (Eastern Mediterranean Sea), through an integrative taxonomic approach that combines morphological and molecular data. The new species, named Clestobothrium brettiae n. sp., can be distinguished from all congeners by its unique ovary shape, and a combination of characters including the arrangement and number of testes. It shares similar morphological characters, with Clestobothrium crassiceps (Rudolphi, 1819) Lühe, 1899, which overlaps in host and geographic distribution. However, morphological differences between Clestobothrium brettiae n. sp. and C. crassiceps also include the arrangement of gladiate spinitriches, as well as a larger scolex, proglottids, testes and cirrus sac, and different ovary morphology. The establishment of Clestobothrium brettiae n. sp. as a novel taxon is supported by detailed morphological description and biometric statistics, in addition to molecular characterisation (based on partial small subunit ribosomal ribonucleic acid [rRNA], partial large subunit rRNA, and internal transcribed spacer region 2), genetic distance, and phylogenetic analyses.

Anisakis spp. are parasites distributed worldwide that often infect marine fish species. This study investigated the prevalence, mean intensity, and Anisakis larvae species, and identified the allergenic potential of T. lepturus caught in the southern coasts of Yogyakarta, Indonesia. In total, 50 fish that were caught by the fishermen were measured for length and weight and examined for Anisakis larvae infection. The results showed that larvae were found in the abdominal cavity (87.03%), organs (7.95%), gonads (2.93%), and digestive systems (2.09%). The prevalence of Anisakis infection was high (64%), with a mean intensity of 7.47 larvae/fish. Molecular analysis revealed that the nematode was Anisakis typica. Therefore, it poses a potential health risk to humans. Consuming fish infected with Anisakis can cause allergic reactions even after the fish has been cooked. The identification was done through protein profile antigen detection of fish flesh, both infected and non-infected, using SDS-PAGE. In this study, the heating process was applied (60℃, 90℃, and 120℃) for 15 minutes. The result of allergenic potential detection from T. lepturus infected by Anisakis showed four protein bands correlated with Anisakis allergens Ani s 1 (24 kDa), Ani s 2 (97 kDa), Ani s 3 (41 kDa), and Ani s 7 (139 kDa) in all the infected fish, both fresh and processed.Keywords:AnisakisAllergenInfectionIntensityPrevalence

Homoploid hybrid speciation (HHS) is an enigmatic evolutionary process where new species arise through hybridisation of divergent lineages without changes in chromosome number. Although increasingly documented in various taxa and ecosystems, convincing cases of HHS in marine fishes have been lacking. This study presents a possible case of HHS in a pelagic marine fish based on comprehensive genomic, morphological, and ecological analyses. Population genomics, species tree estimation, and tests of introgression and admixture identified three sympatric clusters in Megalaspis cordyla in the western Pacific and the admixed nature of one cluster between the others. Moreover, model-based demographic inference favoured a hybrid speciation scenario over introgression for the origin of the admixed cluster. While contemporary gene flow suggested partial reproductive isolation, examination of occurrence data and ecologically relevant morphological characters suggested ecological differences between the clusters, potentially contributing to the reproductive isolation and niche partitioning in sympatry. The clusters are also morphologically distinguishable and thus can be taxonomically recognised as separate species. The hybrid cluster is restricted to the coasts of Taiwan and Japan, where all three clusters coexist. The parental clusters are additionally found in lower latitudes, where they display non-overlapping distributions. Given the geographical distributions, estimated times of species formation, and patterns of historical demographic changes, we propose that the Pleistocene glacial cycles were the primary driver of HHS in this system. We also develop an ecogeographic model of HHS in marine coastal ecosystems, including a novel hypothesis to explain the initial stages of HHS.

Introduction: Evaluation of the nutritional value of fish is critical because fish contain essential fatty acids. The hydrolysis process of fish oil is necessary to determine the fatty acids located at the sn-2 position on triglycerides. Essential fatty acids occupying the sn-2 position are very important to be identified because they are maximally absorbed in the digestive system. Research on the hydrolysis process of fish oil can be optimally conducted using Design Expert software to achieve a perfect hydrolysis percentage. This study aims to obtain optimal pH, temperature, and incubation time for % hydrolysis using Design Expert software. Furthermore, the marine fish should be evaluated based on the position of fatty acids. Methods: Fish samples from the market included Sardinella pilchardus, Euthynnus affinis, Rastrelliger kanagurta, Lutjanus argentimaculatus, and Thunnus sp.. The optimization of % hydrolysis was perfectly carried out using response surface methodology and Design Expert software. After obtaining the optimal pH, hydrolysis time, and temperature, hydrolysis was performed on marine fish samples. Analysis of fatty acid composition was conducted using gas chromatography. Result: The optimal results of the hydrolysis process were achieved at pH 8, a temperature of 50 °C, and a duration of 8 hours and 30 minutes, with a hydrolysis percentage of 65.357 ± 1.047%. Discussion: The strong negative correlation between PUFA and both the ω6/ω3 ratio and thrombogenic index (TI) suggests that higher PUFA intake, particularly omega-3 fatty acids, may reduce inflammatory and thrombotic risks. Additionally, the positive association between PUFA and the P/S ratio supports the cardiovascular benefits of diets rich in polyunsaturated fats over saturated fats. Conclusion: Evaluation of nutritional values based on fatty acids at the sn-2 position indicates that the marine fish with the best dietary levels are Euthynnus affinis, Lutjanus argentimaculatus, Rastrelliger kanagurta, Thunnus sp., and Sardinella pilchardus based on the IQN index.

Systematic analysis of Wnt family genes reveals the potential role of Wnt4 in driving female differentiation in Spotted knifejaw.

A family concept for the genus Stomachicola Yamaguti, 1934 (Digenea: Hemiuroidea) and new hemiuroid species from marine fishes of Vietnam.

Predicted ocean warming will impact the survival and structure of various marine organisms, in particular ectotherms. Phenotypic plasticity enables species to cope with environmental changes, providing a vital buffer for evolutionary adaptations. Yet, the dynamics and molecular mechanisms underpinning these plastic responses remain largely unexplored. Here, we assessed the impact of temperature acclimation on organisms' capacity for thermal plasticity. We conducted a genome-wide transcriptomic analysis on the Acadian redfish, Sebastes fasciatus, exposed to four temperatures (2.5, 5.0, 7.5 and 10.0 ℃) over a long-term period (up to 10 months) followed on some individuals by a short-term temperature change (+2.5 °C or -2.5 °C for 24 hours), simulating natural temperature variation the species could encounter. Our results showed a dynamic transcriptional response to temperature involving various gene functions. The rapid response to temperature shifts, coupled with the sustained expression of specific genes over an extended period highlighted the species' capacity for plasticity in response to temperature changes. We also detected a significant effect of the interaction between the long- and short-term temperature exposures on gene expression, highlighting the influence of the past environment on the response to short-term temperature changes. Specifically, fish acclimated to higher temperatures demonstrated an increased stress-related response to environmental fluctuations, as evidenced by both the shape of their reaction norms and the involvement of stress-related gene functions. This result suggests that temperature conditions predicted for the near future in the Northwest Atlantic will trigger reduced adaptive plasticity to environmental fluctuations, highlighting the species' vulnerability to ocean warming.

Poly- and perfluoroalkyl substances (PFAS) in marine and freshwater fish muscle tissue from Shandong Province and implications for human exposure.

Exploring synergistic contamination of heavy metals and microplastics in marine edible fishes and associated risk status in humans.

Decision-making and public health: How the prevalence of Contracaecum spp. larvae in market-size tilapia may influence fish sample-size to be inspected prior marketing

The acanthocephalan genus Longicollum Yamaguti, 1935 currently comprises 12 fish-parasitic species. Except for L. pagrosomi Yamaguti, 1935, the remaining 11 congeners have not been the subject of molecular phylogenetic studies. Longicollum alemniscus (Harada, 1935) has been found in brackish and marine fish in Taiwan and Japan, but its morphology remains inadequately understood. In this paper, we provide a morphological redescription and infer the phylogenetic position of L. alemniscus within the Pomphorhynchidae. Furthermore, we summarize the morphological characteristics of Longicollum to distinguish it from the morphologically similar genus Paralongicollum Amin, Bauer, and Sidorov, 1991.

A novel indel-based molecular sex identification system for oplegnathus fasciatus: Insights from ndc80 gene polymorphisms and aquaculture applications.

Nervous necrosis virus (NNV) causes a neurologic disease in a wide range of marine fish and poses serious disease risks to marine aquaculture worldwide. Little is known about the presence of NNV along the Atlantic coast of the United States, aside from the presence of barfin flounder nervous necrosis virus (BFNNV) in coldwater species in the northern part of this range. Herein we conducted surveillance for NNV from 2020 to 2022 in the mid-Atlantic region of the United States in black sea bass Centropristis striata, a serranid fish that is found throughout the eastern U.S. coast. Molecular detection methods have identified and characterized red-spotted grouper nervous necrosis virus (RGNNV) sequences at low prevalence throughout the years. Further, in 2022, a higher prevalence of a novel NNV genotype, tentatively named black sea bass nervous necrosis virus (BSBNNV), was characterized for the first time. Though virus isolation was unsuccessful, this study was the first to genetically identify NNV in this region and in this species. These findings highlight the need for further research on NNV to understand epidemiology and virulence in the context of marine fisheries and an emerging marine aquaculture industry in the United States.

Three new species of copepods of the genus Lernanthropus de Blainville, 1822 (Siphonostomatoida: Lernanthropidae) parasitic on marine fishes of Vietnam are described and illustrated: Lernanthropus hexodonis Kovaleva, sp. nov., L. kazachenkoi Kovaleva, sp. nov., and L. marginatus Kovaleva, sp. nov.

Coinfection of large yellow croaker Larimichthys crocea by Trypanosoma sp. (Euglenozoa: Kinetoplastea) and Ceratomyxa xiangshanensis n. sp. (Cnidaria: Myxosporea) in offshore net cage systems in the East China Sea.

Plasma exosomes from viral hemorrhagic septicemia virus-infected olive flounder (Paralichthys olivaceus): Proteomic insights and wound healing effects.

The degree of co‐occurrence between size groups within a population influences key biological processes, such as connectivity and competition within a population. However, the links between co‐occurrence between size group pairs, abundance, and maximum body size among populations remain largely unclear. In this study, we analyzed spatial time series data from 1982 to 2019 to investigate the co‐occurrence between size groups of 54 marine fish populations across three regions (North Sea, Scottish West Coast and eastern Bering Sea). We show that for all the regions, the probability of co‐occurrence for most size group pairs decreased with increasing maximum body size across populations. This suggests that the size group pairs within larger‐bodied populations tend to segregate more in space, whereas those within smaller‐bodied populations tend to mix and aggregate. The co‐occurrence for most size group pairs within populations did not change with abundance, indicating that the tendency of the size groups to aggregate or segregate was mostly insensitive to abundance. Moreover, across populations and regions, the co‐occurrence‐abundance relationship of most size group pairs did not change with the maximum body size except five size group pairs in the North Sea, suggesting that compared to smaller‐bodied populations, these size group pairs within larger‐bodied populations in this region tend to aggregate more with increasing abundance and segregate more with decreasing abundance. These findings provide new insights into the spatial dynamics of size groups, offering valuable implications for understanding population spatial structure and connectivity in marine ecosystems.

Phase separation in innate immunity: Teleost IL6Ra's evolutionary leap against viruses.