Evidence cluster — Aquarium fish (teleost fish) nutrition (peer-reviewed, Europe PMC)

Evidence: Aquarium fish (teleost fish) nutrition

Source: Europe PMC (Europe PubMed Central) REST search — first-hand peer-reviewed abstract records, pulled 2026-08-01. Queries covered nutrient requirements, diet formulation, supplementation and deficiency for teleost fish. The cluster returns 12 representative nutrition studies with abstracts below. Abstract text is verbatim from source; each study is traceable by PMID.

Studies

PMID 41060374 (2026, Conservation biology : the journal of the Society for Conservation Biology) — Extent of threats to marine fish from the online aquarium trade in the United States.. Abstract (opening): 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.

Source: https://pubmed.ncbi.nlm.nih.gov/41060374/

PMID 42116709 (2026, The Journal of experimental biology) — Gut microbial composition varies with host metabolic phenotype in juvenile Atlantic salmon.. Abstract (opening): Standard metabolic rate (SMR) influences growth, behaviour and energy use in fish, yet its relationship with gut microbiota remains unclear. Here, we combined physiological measurements with 16S rRNA sequencing of foregut and hindgut tissue to test whether gut microbial communities differ with metabolic phenotype in juvenile Atlantic salmon. High-SMR fish showed greater growth efficiency and lower body water content than low-SMR fish, indicating higher fat levels. In contrast, microbial differences were most evident in the foregut, where low-SMR fish exhibited significantly higher alpha diversity. Microbial beta-diversity analyses revealed clear segregation among metabolic groups, and distance-based redundancy analysis showed that both SMR and body mass strongly explained variation in foregut microbial composition. Correlation analysis identified a negative association between SMR and members of the Rhodobacteraceae family, which were consistently more abundant in the foregut of low-SMR fish. Together, these findings indicate that the metabolic phenotype is associated with distinct patterns of energy utilisation and gut microbiota composition, suggesting that foregut microbial communities may contribute to individual differences in metabolic strategy.

Source: https://pubmed.ncbi.nlm.nih.gov/42116709/

PMID 42441052 (2026, Journal of veterinary research) — Novel SNPs in the leptin gene: implications for growth performance in cultured European sea bass (Dicentrarchus labrax).. Abstract (opening): <h4>Introduction</h4>Leptin, a class I helical cytokine, regulates growth, appetite, energy homeostasis and reproductive functions in fish. The leptin gene (lep) is a candidate gene for growth trait influence in both farm animals and teleost fish.<h4>Material and methods</h4>This study investigated variations in the lep gene and their associations with growth-related traits in European sea bass (Dicentrarchus labrax) using DNA sequencing.<h4>Results</h4>Twelve novel single-nucleotide polymorphisms (SNPs) were identified in the first and second introns and the third exon of the gene, including a non-synonymous third exon variant (g.11004767C>T) causing an arginine-to-tryptophan substitution. This locus was significantly associated with multiple growth traits, including total and fillet weights and standard, body and post-anal lengths (P-value < 0.05). Analysis revealed two haploblocks; block 1 having four haplotypes (GCG, GTG, ACA and GTA), with GTA associated with the highest total and fillet weights and body length measurements (P-value < 0.01). Block 2 comprised three haplotypes (AG, GG and AA), where AG carriers exhibited superior growth to GG and AA carriers (P-value < 0.01). In silico analysis of the non-synonymous third exon variant (g.11004767C>T) suggested its potential effects on local protein conformation and receptor binding.<h4>Conclusion</h4>These findings indicate that lep gene polymorphisms, particularly the g.11004714G>A locus and specific haplotypes, are associated with growth variability in European sea bass. The identified SNPs and haplotypes may facilitate molecular marker-assisted selection in growth performance breeding programmes in economically important aquaculture species.

Source: https://pubmed.ncbi.nlm.nih.gov/42441052/

PMID 42106141 (2026, Molecular and cellular endocrinology) — Targeting melanocortin-4 receptor (MC4R) family in goldfish (Carassius auratus) for enhanced growth and optimized lipid distribution.. Abstract (opening): Controlling abdominal fat accumulation and appetite have consistently been key research priorities in aquaculture. The melanocortin-4 receptor (MC4R) plays a crucial role in regulating appetite and lipid metabolism. In teleost fish, such as goldfish, there are two or more homologs of MC4R, yet the functions and significance of these homologs remain incompletely understood. To address this, we chose goldfish as a model organism and investigated the functions of caMC4R (Carassius auratus MC4R) and caMC4R-like using molecular docking, RNA interference (RNAi) and RNA sequencing (RNA-seq). Our findings indicate that the third intracellular loop (ICL3) of caMC4R and caMC4R-like differs significantly, resulting in distinct activation of cAMP signaling downstream of the receptor. The knockdown of caMC4R/caMC4R-like promoted appetite and growth in goldfish. Interestingly, the knockdown of caMC4R enhanced muscle lipid accumulation by regulating the expression of pyruvate dehydrogenase (E1) component subunit beta (PDHB). The knockdown of caMC4R-like promoted hepatic lipid accumulation via the PPARγ and SREBP-1c pathways. Overall, the knockdown of caMC4R and caMC4R-like promoted lipid accumulation in the muscle and liver of goldfish, respectively. The results of this study will provide foundational data for investigating the functions of the MC4R subfamily in teleost fish and the significance of genome duplication in fish evolution. In addition, our findings offer actionable insights for enhancing growth performance and modulating body composition in cultured fish populations, offering tangible applications for both nutritional programming and selective breeding in aquaculture production systems.

Source: https://pubmed.ncbi.nlm.nih.gov/42106141/

PMID 42353504 (2026, Animals : an open access journal from MDPI) — Multi-Omics Integration Reveals Synergistic Metabolic Rewiring Underpinning Growth Acceleration in a Hybrid Pompano "Chenhai No. 1".. Abstract (opening): The hybrid golden pompano "Chenhai No. 1" (CH), generated through distant hybridization [(♀ Trachinotus ovatus × ♂ T. blochii) × ♂ T. ovatus], exhibits significantly enhanced growth performance compared to its parental T. ovatus (TO). To elucidate the molecular mechanisms underlying this rapid growth, we performed integrated transcriptomic and untargeted metabolomic profiling of muscle tissue. Transcriptomic analysis identified 3172 differentially expressed genes (DEGs), with weighted gene co-expression network analysis (WGCNA) highlighting the 'darkorange2' module as strongly associated with rapid growth. Key DEGs, including mapk8a, acacb, and pkmb, were upregulated and implicated in energy metabolism, glycolysis, and signal transduction. Metabolomic profiling detected 576 significantly altered metabolites, predominantly enriched in glycolysis, the tricarboxylic acid (TCA) cycle, amino acid metabolism, lipid biosynthesis, and mTOR signaling. Integrated analysis revealed coordinated alterations between core module genes and differential metabolites in interrelated pathways, including correlations between pfkpa/pfkma and glyceraldehyde-3-phosphate, acacb and phosphatidylcholine/phosphatidylethanolamine, and sesn2 and leucine. These findings suggest that the growth advantage of CH arises from the coordinated enhancement of energy metabolism, amino acid sensing, and lipid metabolic remodeling, establishing a synergistic transcription-metabolism regulatory network. This study provides multi-omics insights into the molecular basis of rapid growth in an economically important teleost fish.

Source: https://pubmed.ncbi.nlm.nih.gov/42353504/

PMID 42497081 (2026, FASEB journal : official publication of the Federation of American Societies for Experimental Biology) — SRM-Mediated Spermidine Synthesis Links Lipid Overload With AMPK Pathway to Regulate Hepatic Insulin Signaling and Gluconeogenesis.. Abstract (opening): Polyamine metabolism is essential for cell proliferation and differentiation; however, its specific role in insulin signaling regulation remains poorly understood. Here, we uncover an unexpected role for spermidine synthase (SRM) in linking lipid overload to insulin resistance. In a teleost fish model, we demonstrate high fat diet (HFD) suppresses hepatic SRM expression via X-box binding protein 1 (XBP1)-dependent transcriptional repression. Loss of SRM, either by pharmacological inhibition or siRNA-mediated knockdown, impairs insulin signaling, as evidenced by decreased AKT phosphorylation and increased expression of gluconeogenic enzymes. Conversely, overexpression of SRM enhances insulin sensitivity and suppresses gluconeogenesis. Mechanistically, SRM-mediated regulation of the insulin signaling pathway is dependent on its downstream metabolite spermidine (SPD), which functions through AMP-activated protein kinase (AMPK) pathway, as the beneficial effects of SPD are abolished by the AMPK inhibitor Compound C. In addition, dietary HFD significantly decreases hepatic SPD levels by 35% and reduces the p-AKT/AKT ratio by 58% in croaker, while it elevates blood glucose levels by 39%. Conversely, SPD supplementation increases the p-AKT/AKT ratio by 131% and lowers blood glucose levels by 20%, compared with the HFD group. Taken together, our findings establish the SRM-SPD axis as a critical link between nutritional stress and insulin resistance, and highlight SPD as a potential nutraceutical for combating insulin resistance and glucose intolerance in teleost fish.

Source: https://pubmed.ncbi.nlm.nih.gov/42497081/

PMID 42119748 (2026, Fish & shellfish immunology) — Critical roles of CD4-1+ T cells and their secreted IL-21 in vaccine-induced humoral immunity in grass carp.. Abstract (opening): Although CD4+ T cells are known to play a crucial helper role in mammalian humoral immunity, the function of early-evolved CD4-1+ T cells in teleost fish for assisting B cell-mediated antibody production remain to be elucidated. Using grass carp (Ctenopharyngodon idella) as a model, this study demonstrated that CD4-1+ T cells play a critical role in vaccine-induced antibody production and antibacterial immunity. We confirmed that inactivated Aeromonas hydrophila vaccine significantly induced interleukin-21 (IL-21) expression in grass carp head kidney leukocytes (HKLs), and identified CD4-1+ T cells as the primary cellular source of IL-21. In vitro experiments showed that IL-21 effectively promoted B cell differentiation into plasma cells and enhanced IgM secretion, which synergized with A. hydrophila to exert a more pronounced effect. Meanwhile, our in vivo studies demonstrated that IL-21 possess molecular adjuvant function when co-immunized with A. hydrophila. Depletion of CD4-1+ T cells reduced A. hydrophila-elicited specific IgM levels and antibacterial immune protection, confirming their essential helper function. Injection of IL-21 into CD4-1+ T cell depletion fish can partially improve the survival rate but could not restore antibody levels, indicating that while IL-21 has direct immunoenhancing effects, CD4-1+ T cells are essential for a full antibody response. In conclusion, these results demonstrated the critical roles of CD4-1+ T cells and their secreted IL-21 in vaccine-induced humoral immunity in grass carp, providing a foundation for identifying Tfh-like cells in teleost fish and supporting the potential application of IL-21 as molecular adjuvant in fish vaccines.

Source: https://pubmed.ncbi.nlm.nih.gov/42119748/

PMID 42235724 (2026, Fish & shellfish immunology) — G protein-coupled receptor 119 exerts anti-inflammatory effects on the liver of zebrafish (Danio rerio) via mediating Gs/cAMP-dependent pathway.. Abstract (opening): Hepatic inflammation is a prevalent health issue in farmed fish, which severely compromises liver function and immune homeostasis. G protein-coupled receptor 119 (GPR119) has been implicated in metabolic and immune regulation in mammals; however, its role in teleost fish remains largely unexplored. In this study, zebrafish (Danio rerio) GPR119 was cloned and systematically characterized with respect to its sequence features, tissue distribution, and subcellular localization. Functional analyses demonstrated that activation of GPR119 by the selective agonist MBX-2982 significantly suppressed the expression of pro-inflammatory cytokines in zebrafish hepatocytes. Both gain- and loss-of-function experiments further confirmed the anti-inflammatory role of GPR119 under palmitic acid (PA) - and lipopolysaccharide-induced inflammatory conditions in vitro, and in vivo. Mechanistically, GPR119 activation engaged Gs- and Gq-dependent signaling, leading to enhanced cyclic adenosine monophosphate (cAMP)-cAMP-response element binding protein (CREB) activity, inhibition of nuclear Factor kappa-B (NF-κB) p65 phosphorylation, and attenuation of inflammatory gene expression. In addition, β-Arrestin-extracellular regulated protein kinases (ERK)-associated signaling was involved in the fine-tuning of CREB-mediated inflammatory regulation. Collectively, these findings identify GPR119 as a critical negative regulator of hepatic inflammation in zebrafish and provide mechanistic insights into its immunomodulatory function, highlighting its potential as a therapeutic target for improving liver health in aquaculture species.

Source: https://pubmed.ncbi.nlm.nih.gov/42235724/

PMID 42019591 (2026, Fish & shellfish immunology) — Immunoglobulin M response in different intestinal segments of largemouth bass (Micropterus salmoides) following largemouth bass virus (LMBV) infection.. Abstract (opening): In teleost fish, the gut functions not only as a primary site for nutrient digestion and absorption but also as a critical mucosal immune organ. Although the functional heterogeneity of nutrient absorption among different intestinal segments has been well characterized, the segment-specific features of intestinal immune responses remain poorly understood, particularly with regard to mucosal IgM responses. In this study, we established a virus infection model via intraperitoneal injection and demonstrated that the virus triggers robust innate and adaptive immune responses in the gut of largemouth bass (Micropterus salmoides), accompanied by significant upregulation of multiple immune-related genes. The secondary infection induced a stronger IgM response compared to primary infection, characterized by a significant increase in IgM+ B cell proportions and markedly elevated LMBV-specific IgM titers. In addition, the rise in LMBV-IgM titers may be closely associated with their specific neutralizing activity against the virus. Notably, intestinal IgM responses exhibited clear segmental heterogeneity, with the hindgut displaying substantially stronger IgM responses than the foregut and midgut. Collectively, this study highlights the pivotal role of the hindgut in antiviral intestinal immunity and provides a theoretical foundation for the development of mucosal vaccines in teleost fish.

Source: https://pubmed.ncbi.nlm.nih.gov/42019591/

PMID 41628736 (2026, Fish & shellfish immunology) — Two CC motif chemokine 20-like genes differentially regulate leukocyte migration and survival via CC chemokine receptor 6 in ayu (Plecoglossus altivelis).. Abstract (opening): Chemokine ligand 20 (CCL20) is a key mediator of inflammatory and homeostatic responses in mammal, acting through its receptor CC chemokine receptor 6 (CCR6). However, its functional roles in teleost fish remain poorly defined. In this study, we identified two CCL20-like genes (PaCCL20l1 and PaCCL20l2) from ayu (Plecoglossus altivelis). Phylogenetic analysis confirmed their classification within the CCL20 subgroup. Tissue distribution analysis revealed ubiquitous expression of both genes, which were significantly upregulated in multiple tissues (liver, spleen, head kidney, gill, skin, and intestine) following infection with Vibrio anguillarum, albeit with distinct expression profiles. We produced the recombinant mature peptide of PaCCL20ls (rPaCCL20l1 and rPaCCL20l2) and generated specific antibodies. Functional assays demonstrated that both rPaCCL20l1 and rPaCCL20l2 exhibit chemotactic, and anti-apoptosis activities, but with differing cell specificities. rPaCCL20l1 attracted lymphocytes and neutrophils and inhibited lymphocyte apoptosis. In contrast, rPaCCL20l2 attracted monocytes/macrophages (MO/MΦ), lymphocytes, and neutrophils, and suppressed apoptosis in both MO/MΦ and lymphocytes. Crucially, neutralizing PaCCR6 completely abolished all effects of both rPaCCL20l1 and rPaCCL20l2. In conclusion, our findings demonstrate that PaCCL20l1 and PaCCL20l2 play pivotal but distinct roles in ayu immunity by modulating leukocyte recruitment and survival via PaCCR6 pathway.

Source: https://pubmed.ncbi.nlm.nih.gov/41628736/

PMID 41720367 (2026, Fish & shellfish immunology) — Construction of a multi-tissue immune atlas for Chinese tongue sole (Cynoglossus semilaevis) reveals granulocyte functional adaptation and underlying regulatory mechanisms.. Abstract (opening): Innate immunity in teleost fish relies heavily on granulocytes for host defense. However, how these cells functionally adapt to distinct tissue microenvironments remains poorly understood. To address this, we constructed a multi-tissue immune atlas for Cynoglossus semilaevis by integrating single-cell RNA sequencing (scRNA-seq) data from blood, liver, spleen, and head kidney. We identified five transcriptionally distinct granulocyte subsets (Gr1-Gr5), each with divergent roles in inflammation, immunoregulation, and complement activity; moreover, these subsets exhibited tissue-specific distributions. Pseudotime analysis revealed a bifurcated developmental trajectory from a shared progenitor pool residing in the head kidney and spleen, characterized by the dynamic expression of the cxcr2/cxcr4 axis and branch-specific transcription factors. While sharing core metabolic pathways, granulocyte subsets displayed tissue-specific adaptations and an inferred communication strategy involving a conserved cd44b-mediated module. Our findings systematically characterize the patterns of granulocyte adaptation in a teleost model, providing insights into fish immunology and aquaculture disease control.

Source: https://pubmed.ncbi.nlm.nih.gov/41720367/

PMID 42200157 (2026, Aquaculture nutrition) — Dietary Substitution of Soybean Meal With Phaeodactylum tricornutum Meal Improves Growth, Skin Pigmentation, Nutrient Retention, and Lipid Metabolism in Grass Carp (Ctenopharyngodon idella).. Abstract (opening): The search for alternative protein sources to replace soybean meal (SBM) is crucial for the sustainable development of aquaculture. This study investigated the effects of dietary replacement of SBM with Phaeodactylum tricornutum meal (PTM) on grass carp (Ctenopharyngodon idella) (65.00 ± 0.60 g). Five isonitrogenous and isolipidic diets were formulated, in which PTM replaced 0%, 25%, 50%, 75%, and 100% of SBM protein (denoted as PT0 to PT4). Fish fed diets PT2-PT4 showed significant improvements in specific growth rate (SGR) compared to the PT0 group after the 56-day trial (p < 0.05). All PTM groups exhibited significantly higher feed efficiency (FE) (p < 0.05). Skin pigmentation was markedly improved, with significantly higher redness (a ∗) and yellowness (b ∗) values observed in fish fed PTM-containing diets. Muscle nutritional quality was enhanced, as evidenced by significantly higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the PT3 and PT4 groups (p < 0.05). Notably, nitrogen (N) and phosphorus (P) retention efficiencies were significantly elevated in the PT2-PT4 groups (p < 0.05), indicating reduced nutrient discharge into the environment. Moreover, whole-body lipid content decreased with increasing graded levels of PTM substitution, and plasma triglycerides (TGs) and cholesterol levels were significantly reduced in all PTM-supplemented groups. Mechanistically, dietary PTM supplementation upregulated hepatic mRNA expression of lipolytic genes (peroxisome proliferator-activated receptor alpha [pparα], carnitine palmitoyltransferase 1 [cpt1], hormone-sensitive lipase [hsl], and adipose TG lipase [atgl]) and downregulated lipogenic genes (fatty acid synthase [fas], acetyl-CoA carboxylase alpha [acc], stearoyl-CoA desaturase-1 [scd1], and diacylglycerol O-acyltransferase 1 [dgat1]), suggesting transcriptional regulation that enhances lipid catabolism and inhibits lipogenesis. In conclusion, PTM can effectively replace dietary SBM protein while simultaneously improving growth performance, skin quality, and nutrient utilization in grass carp and reducing potential environmental pollution. These findings confirm that PTM is capable of improving nutrient utilization and reducing N/P output. PTM therefore represents a promising alternative protein ingredient for developing eco-friendly aquafeeds.

Source: https://pubmed.ncbi.nlm.nih.gov/42200157/

Source text: pdf-raw/evidence/europepmc_fish_nutrition_2026-08-01.txt (Europe PMC first-hand abstracts, pulled 2026-08-01).

Evidence cluster — Aquarium fish (teleost fish) nutrition (peer-reviewed, Europe PMC)

Evidence: Aquarium fish (teleost fish) nutrition

Studies

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