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Background Parental contributions to offspring phenotype extend beyond genetic inheritance, encompassing non-genetic factors that influence early development. However, the interplay between maternal and paternal effects remains poorly understood. This study investigates these contributions in Eurasian perch ( Perca fluviatilis ) — a valuable model to study parental effect in finfishes — by analyzing early life traits and transcriptomic profiles of larvae resulting from crosses between wild and domesticated parents. Results Maternal effects dominated key developmental traits, including hatching success, growth, and swim bladder inflation. Transcriptomic analysis revealed a complex regulatory interplay, with 573 genes under exclusive maternal control, while no genes were solely influenced by paternal input. Maternal-effect genes were primarily associated with metabolic, developmental, and stress-response pathways, shaping early larval physiology. Further analysis identified Eurasian-perch-specific candidate maternal-effect genes, such as crtac1 , slc16a7 , cox5b , kdr , cald1 , and bin2 , highlighting their potential role in early development. Although paternal contributions were limited, a subset of genes exhibited conditional paternal influence, suggesting a nuanced parental interplay in gene expression regulation. Conclusions These findings challenge the traditional perspective of strictly coordinated parental contributions, instead revealing a dynamic parental interplay over gene expression and offspring traits. The dominance of maternal effects suggests a primary role in shaping early development, while paternal factors may modulate expression patterns in a context-dependent manner. This study enhances our understanding of parental effects in fish, providing valuable insights for aquaculture breeding strategies and evolutionary biology research.

BackgroundDespite specific restrictions on their production and use, per- and polyfluoralkyl substances (PFAS) are still omnipresent in the environment, including aquatic ecosystems. Most biomonitoring studies have investigated the PFAS concentrations in indigenous organisms, whereas active biomonitoring has only been used sporadically. In the present study, accumulated PFAS concentrations were measured in indigenous fish, European perch (Perca fluviatilis) and European eel (Anguilla anguilla), and in translocated freshwater mussels (Dreissena bugensis and Corbicula fluminea) at 44 sampling locations within the main water basins of Flanders, the northern part of Belgium. Finally, both human health risk and ecological risk were assessed based on accumulated concentrations in fish muscle.ResultsAmong locations, ΣPFAS concentrations ranged from 8.56–157 ng/g ww (median: 22.4 ng/g ww) in mussels, 5.22–67.8 ng/g ww (median: 20.8 ng/g ww) in perch, and 5.73–68.8 ng/g ww (median: 22.1 ng/g ww) in eel. Concentrations of PFOA and PFTeDA were higher in mussels compared to fish, whereas for PFDA and PFUnDA the opposite was true. A comparison of concentrations on a wet weight basis between both fish species showed significantly higher PFDoDA, PFTrDA, PFTeDA and PFOA concentrations in eel compared to perch and significantly higher concentrations of PFDA and PFOS in perch. In mussels, PFAS profiles were dominated by PFOA and showed a higher relative contribution of short-chained PFAS, while PFAS profiles in fish were dominated by PFOS. Furthermore, all mussel species clearly occupied a lower trophic level than both fish species, based on a stable isotope analysis.ConclusionsBiomagnification of PFDA, PFUnDA and PFOS and biodilution of PFOA and PFTeDA were observed. Translocated mussels have been proven suitable to determine which PFAS are present in indigenous fish, since similar PFAS profiles were measured in all biota. Finally, mean PFAS concentrations in fish did pose a human health risk for eel, although tolerable daily intake values for perch were close to the reported daily consumption rates in Belgium and exceeded them in highly contaminated locations. Based on the ecological risk of PFOS, the standard was exceeded at about half of the sampling locations (44% for perch and 58% for eel).

1. Differences in energy use between genders is a probable mechanism underlying sexual size dimorphism (SSD), but testing this hypothesis in the field has proven difficult. We evaluated this mechanism as an explanation for SSD in two North American percid species - walleye Sander vitreus and yellow perch Perca flavescens. 2. Data from 47 walleye and 67 yellow perch populations indicated that SSD is associated with the onset of maturation: typically, males of both species matured smaller and earlier and attained a smaller asymptotic size than females. Males also demonstrated equal (perch) or longer (walleye) reproductive life spans compared with females. 3. To examine whether reduced post-maturation growth in males was due to lower energy acquisition or higher reproductive costs we applied a contaminant mass-balance model combined with a bioenergetics model to estimate metabolic costs and food consumption of each sex. Mature males exhibited lower food consumption, metabolic costs and food conversion efficiencies compared with females. 4. We propose that slower growth in males at the onset of maturity is a result of decreased feeding activity to reduce predation risk. Our finding that SSD in percids is associated with the onset of maturity is supported by laboratory-based observations reported elsewhere, showing that changes in growth rate, consumption and food conversion efficiency were elicited by oestrogen (positive effects) or androgen (negative effects) exposure in P. flavescens and P. fluviatilis. 5. Researchers applying bioenergetic models for comparative studies across populations should use caution in applying bioenergetic models in the absence of information on population sex ratio and potential differences between the sexes in energetic parameters.

Anthropogenic climate change is forecast to drive regional climate disruption and instability across the globe. These impacts are likely to be exacerbated within biodiversity hotspots, both due to the greater potential for species loss but also to the possibility that endemic lineages might not have experienced significant climatic variation in the past, limiting their evolutionary potential to respond to rapid climate change. We assessed the role of climatic stability on the accumulation and persistence of lineages in an obligate freshwater fish group endemic to the southwest Western Australia (SWWA) biodiversity hotspot. Using 19,426 genomic (ddRAD-seq) markers and species distribution modelling, we explored the phylogeographic history of western (Nannoperca vittata) and little (Nannoperca pygmaea) pygmy perches, assessing population divergence and phylogenetic relationships, delimiting species and estimating changes in species distributions from the Pliocene to 2100. We identified two deep phylogroups comprising three divergent clusters, which showed no historical connectivity since the Pliocene. We conservatively suggest these represent three isolated species with additional intraspecific structure within one widespread species. All lineages showed long-term patterns of isolation and persistence owing to climatic stability but with significant range contractions likely under future climate change. Our results highlighted the role of climatic stability in allowing the persistence of isolated lineages in the SWWA. This biodiversity hotspot is under compounding threat from ongoing climate change and habitat modification, which may further threaten previously undetected cryptic diversity across the region.

The current study evaluated the effects of dietary supplementation of Triphala (TR) on yellow perch ( Perca flavescens ) growth performance, immune response, related gene expression, and intestinal histological structure. The experimental design included four groups: one control group (0% TR/ kg diet) and three TR-supplemented groups with 2, 4, and 6%/kg diet for four weeks and each group was allocated in triplicates with 30 fish each. Sampling included three fish from each replicate for evaluating immune response and gene expression. Findings showed that Triphala markedly improved growth performance, Immunoglobulin M (IgM) levels, lysozyme activity, and Nitric Oxide (NO) activity with the most significant (p < 0.05) results for 6% TR/kg diet group. The TR groups also showed significantly decreased glucose and cortisol concentrations with the lowest values for the 6% TR/kg diet group. Moreover, TR-incorporated groups revealed significantly upregulated expression (p < 0.05) of growth [Insulin-Like Growth Factor-1 (IGF-1)] and immune [Alpha 2 Macroglobulin (A2M), Serum Amyloid A (SAA) and Complement Component C3 (CCC3)] genes in incorporated groups, specially the 6% TR group. Moreover, the intestinal morphometric histological analysis revealed that villus length was increased in a dose-dependent manner, coping with other enhanced parameters. Current results endorse the positive effects of Triphala incorporation on yellow perch farming as a safe alternative option to enhance growth performance, immune response, related gene expression, and intestinal histology.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Olfaction, which is mediated by olfactory receptor (OR) genes, is essential in the daily life of fish, especially in foraging. However, Chinese perch (Siniperca chuatsi) is believed to prey with reliance on vision and lateral sensation, but not on olfaction. Therefore, understanding the evolutionary dynamics of the Chinese perch OR repertoire could provide insights into genetic evidence for adapting to a decreasing reliance on olfaction. Here, we reported a whole-genome analysis of the Chinese perch OR repertoire. Our analysis identified a total of 152 OR genes, including 123 functional genes and 29 pseudogenes, and showed their genomic organization. A phylogenetic tree was constructed, and the phylogenetic relationships of teleosts ORs was illustrated. The dN/dS (global ratios of non-synonymous to synonymous) analysis demonstrated that OR groups all appeared to be under purifying selection. Among the five Percomorpha fishes, Chinese perch only had 22 subfamilies, suggesting a decrease in OR diversities. The species-specific loss of subfamily 56 and 66 in Chinese perch, of which the genes belonged to subfamily 66, were orthologs of OR51E2, which recognized the plant odorant β-ionone, indicating that extremely piscivorous fish which might lose those receptors responded to plant-related odors. Finally, the expression profiles of OR genes in the olfactory epithelium at different developmental stages were investigated using RNA-seq data. From the aforementioned results, the evolution of the OR repertoire may be shaped by the adaption of vision-dependent specializations for foraging in Chinese perch. The first systematic study of OR genes in Chinese perch could provide valuable genomic resources for the further investigation of olfactory function in teleosts.

Domestication has altered a variety of traits within the Eurasian perch (Perca fluviatilis), including phenotypic, physiological and behavioral traits of Eurasian perch (Perca fluviatilis). Little is known, however, about the genetic changes between domesticated and wild Eurasian perch. In this study, we assembled a high-quality de novo reference transcriptome and identified differentially expressed genes between wild and domesticated Eurasian perch. A total of 113,709 transcripts were assembled, and 58,380 transcripts were annotated. Transcriptomic comparison revealed 630 differentially expressed genes between domesticated and wild Eurasian perch. Within domesticated Eurasian perch there were 412 genes that were up-regulated including MHCI, MHCII, chia, ighm within immune system development. There were 218 genes including try1, ctrl, ctrb, cela3b, cpa1 and cpb1, which were down-regulated that were associated with digestive processes. Our results indicated domestication drives the changes of immune and digestive system of Eurasian perch. Our study not only provide valuable genetic resources for further studies in Eurasian perch, but also provide novel insights into the genetic basis of physiological changes in Eurasian perch during domestication process.

Predators are increasingly recognized as key elements in food webs because of their ability to link the fluxes of nutrients and energy between spatially separated food chains. However, in the context of food web connectivity, predator populations have been mainly treated as homogeneous units, despite compelling evidence of individual specialization in resource use. It is conceivable that individuals of a predatory species use different resources associated with spatially separated food chains, thereby decoupling cross-habitat linkages. We tested whether intrapopulation differences in habitat use in the generalist freshwater predator Eurasian perch (Perca fluviatilis) led to long-term niche partitioning and affected the degree of ecological habitat coupling. We evaluated trophic niche variability at successively larger timescales by analyzing gut contents and stable isotopes (δ¹³C and δ¹⁵N) in liver and muscle, tissues that provide successively longer integration of trophic activity. We found that the use of distinct habitats in perch led to intrapopulation niche partitioning between pelagic and littoral subpopulations, consistent through the various timescales. Pelagic fish showed a narrower niche, lower individual specialization, and more stable trophic behavior than littoral fish, as could be expected from inhabiting a relatively less diverse environment. This result indicated that substantial niche reduction could occur in a generalist predator at the subpopulation level, consistent with the use of a habitat that provides fewer chances of individual specialization. We showed that intrapopulation niche partitioning limits the ability of individual predators to link spatially separated food chains. In addition, we suggest a quantitative, standardized approach based on stable isotopes to measure the degree of habitat coupling mediated by a top predator.

The aim of this study was to assess the glycogen content in the muscle and liver tissues of the climbing perch (Anabas testudineus) exposed to sublethal concentrations of Cd and Pb over 28 days of exposure and 14 days of depuration. Muscle and liver glycogen levels in A. testudineus after Pb or Cd treatment were significantly lower (p < 0.05) than that of A. testudineus in the control group during the exposure phase. In the recovery phase, muscle, and liver glycogen levels in A. testudineus increased in all Pb treatment groups, whereas they continuously decreased in all Cd treatment groups. Fish affected by Cd had obvious difficulties recovering from the stress response. It was concluded that exposure to the tested concentrations of Pb and Cd could be a potent endocrine activity disruptor, which may lead to adverse impacts on the health of A. testudineus.