Abstract Bony fishes (Osteichthyes) occupy a diverse range of aquatic habitats, yet the ecological transitions underlying their early evolution remain debated. Extant “living fossil” lineages—such as lungfishes and basal ray-finned fishes—are primarily restricted to benthic freshwater habitats, raising questions about the ancestral ecology of bony fishes. To investigate this, we reconstructed and expressed visual pigments from both extant and inferred ancestral taxa in vitro, enabling characterization of their spectral sensitivities. The results reveal that the ancestral visual phenotype is most consistent with adaptation to shallow-water light conditions. Furthermore, parallel shifts in the spectral tuning of visual pigments across both lobe-finned and ray-finned fish lineages were observed, with consistent patterns of shorter wavelength tuning in middle/long-wavelength-sensitive pigments, paired with longer wavelength shifts in others. The shifts of spectral tuning support an ecological transition from marine to freshwater habitats. Additionally, changes in rhodopsin retinal release rates and signatures of positive selection on opsin genes further point to independent visual adaptations to freshwater environments in both lineages. These findings suggest that early bony fish evolution involved ecological expansion from shallow marine habitats into deeper or more turbid freshwater environments, as reflected in parallel adaptations of visual systems to benthic photic conditions.

A line with no hook: longline-associated passive eDNA samplers for deep-sea fish monitoring.

RBX1 and RBX2 promote GCRV replication in grass carp (Ctenopharyngodon idella).

Perciforms or perch-like bony fishes belonging to the families Coiidae (tigerfishes), Dinopercidae (cavebasses), Lethrinidae (emperors), Lobotidae (tripletails), Nemipteridae (threadfin breams), and Pentacerotidae (armorheads) were reported from Pakistan. Spangled emperor, belonging to the Family Lethrinidae, Atlantic tripletail, belonging to Lobotidae, Japanese threadfin bream, and Randall’s threadfin bream, belonging to Family Nemipteridae, are considered to be of commercial importance, which are not only locally consumed but also exported. Sindh is one of the type localities of the lampfish (Dinoperca petersii), which was reported to be of common occurrence about 150 years ago and is now found to be almost extinct in Pakistan. On the contrary, Atlantic tripletail was a rare occurrence about 15 years ago; however, it is now landed in appreciable commercial quantities and exported. The Families Lethrinidae, Nemipteridae, Lobotidae, Dinopercidae, Coiidae, and Pentacerotidae are represented by 34 species in Pakistan

Urban coastal ecosystems face increasing anthropogenic pressures and environmental variability, yet the consequences for multitrophic biodiversity and ecosystem networks remain poorly resolved. Here, we combine environmental DNA metabarcoding, visual surveys, flow cytometry, and environmental measurements to examine the spatiotemporal dynamics of marine metazoans, protists, and prokaryotes across estuarine, transitional, and oceanic habitats in Hong Kong's urbanized coastal waters. Using permutational multivariate analysis of variance (PERMANOVA), we demonstrate that environmental control over community composition weakens systematically at higher trophic levels. The variance explained by seasonal and spatial interaction was highest for prokaryotes (R2 = 0.76) and protists (0.59), but notably lower for benthic fauna (0.41) and bony fish (0.32). Co-occurrence network analysis revealed that oceanic habitats, dominated by heterotrophic prokaryotes, omnivorous fish, and hard corals, supported the most complex and stable multitrophic networks, with an average complexity of 0.54 compared to estuarine (0.23) and transitional habitats (0.29). Structural equation modeling further revealed habitat-specific drivers: temperature exerted the strongest direct effect in estuarine habitats (>0.44), while biotic interactions involving primary producers played a dominant role in oceanic habitats (direct effect >0.28). In contrast, transitional habitats lacked significant environmental or biotic drivers, indicating a system in flux where community dynamics are likely governed by complex variables beyond standard environmental or biotic regulation. These findings demonstrate the gradient-dependent interplay of environmental filtering and biotic regulation in shaping coastal ecosystem stability. Our results also highlight the value of an integrated eDNA-based framework for monitoring biodiversity and ecosystem change, providing insights for the management of urban marine environments under global change.

Oropharyngeal food processing exhibits a remarkable diversity among vertebrates, reflecting the evolution of specialised 'processing centres' associated with the mandibular, hyoid, and branchial arches. Although studies have detailed various food-processing strategies and mechanisms across vertebrates, a coherent and comprehensive terminology is lacking. Here, we provide a synthesis, including a unified terminology for the intricate complexity of vertebrate oropharyngeal processing. Among gnathostomes, mandibular food processing predominates, ranging from discrete bites to rhythmic, cyclic chewing facilitated by precise tongue mechanics in aquatic and terrestrial environments alike. By contrast, some taxa have abandoned oropharyngeal processing entirely, relying instead on post-oesophageal strategies such as gastric milling and chemical digestion. Interestingly, teleost (bony) fishes illustrate the evolutionary trade-off between increased jaw protrusion for prey capture and reduced mandibular processing capacity. They compensated for this trade-off by developing derived processing behaviours early in their evolutionary development. Through the re-evolution of mandibular chewing, they succeeded in utilising all three known processing centres. Mastication is a specialised, dimensionally complex form of unignathic mandibular chewing (i.e. chewing restricted to the lower jaw) exclusive to mammals. However, our findings demonstrate that dimensionally complex forms of mandibular chewing have arisen independently multiple times and are widespread among gnathostomes. Notably, diverse taxa, including elasmobranch stingrays, Australian lungfish, sirenid salamanders, various songbirds, herbivorous turtles, and the tuatara, exhibit complex jaw movements combining arcuate, longitudinal, and sometimes transverse components enabled by specialised jaw joints, suspensions, and intracranial motions ('cranial kinesis'). From a comparative, functional-morphological perspective, mammalian mastication may best be characterised as dimensionally complex chewing mediated by the secondary or temporomandibular joint. By contrast, analogous dimensionally complex non-mammalian chewing involving motions confined to the primary or quadrate-articular jaw joint qualifies as pseudomastication. Both mastication and pseudomastication resemble functional masticatory behaviours, while those incorporating intracranial motions and movements of the jaw suspension belong to distinct categories. Our anatomical analysis highlights the convergent evolution of dimensionally complex chewing among gnathostomes and emphasises the importance of comprehensive studies on jaw development and function to deepen our understanding of the evolution of oropharyngeal processing.

The first identification of constitutive heterochromatin and NOR-bearing chromosomes in the prehistoric bony fish whiting, Merlangius merlangus, using the latest short-term method

Cladoselache, a puzzling ancient shark-like fish Loren E. Babcock, Professor in the School of Earth Sciences at The Ohio State University, introduces research on Cladoselache, a puzzling ancient shark-like fish. The Devonian Period, ~420 to 359 million years ago, is known in colloquial terms as the “Age of Fishes.” During this time, early cartilaginous and bony fishes experienced substantial diversification and adaptation to varied habitats. One characteristic and commonly illustrated Devonian fish is the shark-like Cladoselache (pronounced “klade-oh-sell-æ-key”), known from numerous specimens, some virtually complete, found in Late Devonian-age (~370 million-year-old) iron-carbonate concretions collected in and around Cleveland, Ohio, U.S. (1-4)

Located in the Lombardy Basin of Northern Italy, the Osteno Konservat-Lagerstätte preserves an exceptionally diverse Lower Jurassic marine assemblage that, despite yielding extraordinary amounts of data over the past 60 years due to the remarkable preservation of its specimens, has long had its vertebrate component largely overlooked. This study presents a detailed morphological and taxonomic analysis of the bony fish fauna recovered from this unique deposit. Seven distinct taxa have been identified, four of which are shared with the renowned Lyme Regis Lagerstätte (Dorset, UK): Holophagus cf. gulo, Dapedium sp., Furo sp., and Dorsetichthys bechei, a unique stem teleost whose occurrence at Osteno further strengthens the possibility of faunal contact between English and northern Italian Sinemurian communities. Three novelties characterize the Osteno ichthyofauna: Ostenolepis marianii n. gen. et sp., a small palaeoniscimorph with finely ornamented scales; Peripeltopleurus jurassicus n. sp., the last representative of the Peltopleuriformes, an order previously restricted to the Middle and Upper Triassic; and Pholidolepis teruzzii n. sp., a stem-teleost related to Pholidolepis dorsentensis from Lyme Regis, but uniquely lacking any scale covering. The discovery of these taxa significantly contributes to our understanding of Sinemurian ichthyofaunas while shedding new light on the paleoenvironmental dynamics along the northwestern margin of the Neotethys. Overall, this study underscores the critical importance of the Osteno site for reconstructing patterns of diversity and biogeographic connectivity during a pivotal interval in vertebrate evolution.

Fibrillar collagens are the most abundant structural proteins in vertebrates, forming the backbone of connective tissues such as skin, bone, tendon, and cartilage. In bony fish (teleosts), fibrillar collagens exhibit unique genetic and biochemical properties that reflect a complex evolutionary history of this taxonomic group and its adaptation to diverse aquatic environments-from tropical to polar habitats. This review summarises the current understanding of the genetic organisation and biochemical characteristics of fibrillar collagens in bony fish. They show significant differences in amino acid composition to mammalian collagens, especially in cold-adapted species, where collagens display lower thermal stability and reduced hydroxyproline content relative to their mammalian counterparts.Advances in genomic, transcriptomic, and proteomic profiling have provided new perspectives on the molecular diversity and tissue-specific roles of collagen chains in teleosts. Furthermore, the biomedical potential of fish-derived collagens is receiving growing attention, particularly in biomaterials, wound healing, tissue engineering, and drug delivery systems, owing to their biocompatibility, low immunogenicity, and ease of extraction from byproducts of the fishing industry.By looking at molecular, structural, and applied perspectives, this review highlights the relevance of bony fish collagens as a subject of fundamental biological interest and as a valuable resource for biotechnological and biomedical innovation.

Ectodysplasin A regulates the development of scale and intermuscular bone in teleosts.

ABSTRACT Merluccius productus , commonly referred to as the Pacific Hake, is well known as a relevant species in the structure and functioning of its marine food web networks, acting as a foraging species. Additionally, it represents an important resource for the fishing industry. Nevertheless, little is known about its feeding habits. Therefore, this work describes the diet of the Pacific hake inhabiting the Gulf of California. Samples were obtained from six exploratory fishing research trips conducted between 2014 and 2017. The Prey‐Specific Index of Relative Importance (%PSIRI) was used to quantify the dietary components of the Pacific hake. Additionally, to determine its feeding strategy, a similarity analysis was conducted and the Levin's Index and Morisita–Horn Index were calculated. The sampling included 1772 organisms with sizes ranging from 13.3 to 98.4 cm TL. The analysis of 39.2% of stomachs revealed the presence of different prey items, allowing the identification of 23 distinct prey types grouped into three categories: bony fish, crustaceans, and mollusks. The Prey‐Specific Index of Relative Importance indicated that the diet is mainly composed of Solenocera mutator (25.2%), fish remains (24.9%), Nyctiphanes simplex (18.7%), and Benthosema panamense (8.3%), collectively accounting for 77.1% of the diet composition. The low Levin's index value (Bi = 0.19) classified the Pacific hake as a specialized predator, while the Morisita–Horn index indicated a moderate level of dietary overlap (Cλ = 0.42). The temporal similarity analysis revealed an overall similarity of 60%, allowing the identification of three distinct groups. Notably, Group B, composed of stomach contents from F‐2014 and C‐2014, exhibited a higher similarity of 76.1%. The highest contribution to the similarity of this group was represented by the euphausiids N. simplex (41.03%). Our results suggest that M. productus primarily feeds on highly abundant and available prey species in its environment, predominantly pelagic crustaceans, performing vertical migration to feed. The high frequency of crustaceans such as S. mutator and N. simplex , along with the fish B. panamense , further supports the classification of M. productus as a specialized predator.

The Ypresian (lower Eocene) fish-bearing site of Monte Solane (Verona province, northern Italy) was discovered in the early 2000s, and its stratigraphy was thoroughly investigated more than a decade ago. However, its ichthyofauna, largely dominated by mesopelagic bony fishes, remained largely unstudied, even though it represents the second richest assemblage in the Verona province, ranking immediately after the Bolca Lagerstätten, which are globally renowned for their exceptionally abundant and diverse reef-associated fish assemblages. The scientific relevance of Monte Solane resides in being, along with the Solteri Lagerstätte (Trento province, northern Italy), the nearly coeval bathyal equivalent of Bolca. The Monte Solane ichthyofauna, represented by almost 200 collected specimens, comprises what reflects a mesopelagic assemblage including stomiiforms (Gonostomatidae and Phosichthyidae), myctophiforms (Myctophidae), and various percomorphs (Euzaphlegidae, Gempylidae, and Trichiuridae), plus a few more groups usually linked to the coastal epipelagic or benthic habitats (e.g., Clupeiformes and Apogonidae). Several new taxa are established herein: Acanthophleges lessiniae n. gen. et n. sp., Bolcaichthys solanensis n. sp., Contemptor mastinoi n. gen. et n. sp., Eomastix zabimaru n. gen. et n. sp., Lepidoclupea renga n. gen. et n. sp., Sabbathichthys osbournei n. gen. et n. sp., Thyrsitoides cangrandei n. sp., and Veronaphleges ambrosii n. sp. The stratigraphic relationships of the Monte Solane and Solteri sections are also investigated, and their assemblages are compared to better understand the main features of the Eocene mesopelagic environments of the western part of the Tethys. Exploring these sites can help to unveil the paleontological characters of the most ancient known Cenozoic deep-water Lagerstätten known, and also to better define the structure of the pelagic fish communities during the demise of the Early Eocene Climatic Optimum (EECO; ~ 53.2-49.1 Ma), the interval of the Cenozoic with the warmest long-term global average temperature and highest CO2 levels.

The results of the trawl survey of the research vessel Professor Kaganovsky over four seamounts (Annei, Jingu, Ojin, and Koko) of the Emperor Seamount Chain in 2019 are presented. Seventy-three species of pelagic and bottom-dwelling cartilaginous and bony fishes from 40 families were collected. Morphological diagnoses are presented for each species, with taxonomic comments for the poorly known taxa. The obtained collection includes 11 species new to science or of uncertain taxonomic position, 9 species newly reported for the Emperor Seamounts, and one new record Linophryne arborifera for the Pacific Ocean. For individual seamounts, 27 fish species were recorded for the first time at Annei, 12 species at Ojin, 4 species at Koko, and 2 species at Jingu Seamounts. Cytochrome c oxidase subunit I (COI) or cytochrome b (Cyt b) sequences were obtained for 36 species belonging to 22 families, including 13 species for which the barcode was flagged for the first time and the sequences made available. Cryptic diversity was revealed within the genera Cyclothone, Argyropelecus, and Chauliodus. According to our data, a boundary between the boreal and subtropical fish communities was found between Nintoku and Jingu Seamounts, with a transitional zone over Jingu and Ojin Seamounts at 37–39° N. However, the distribution of the subtropical species to the north may be limited by the increasing of summit depths in the northern subsection of the chain rather than any oceanographic or climatic barriers.

In ray-finned fish (Neopterygii), the symplectic together with the palatoquadrate ossification and the hyomandibula forms the suspensorium. However, in paleoniscoids, the suspensorium was not formed, and the symplectic was attached to the lower jaw behind the jaw joint. Modern hypotheses do not take into account certain morphofunctional features of the symplectic in paleoniscoids. Meanwhile, understanding the biomechanics of the paleoniscoid skull is important for hypothesizing about the evolution of ray-finned fish (Actinopterygii). Drawing on literature data about the structure of paleoniscoid heads, we conducted a graphical analysis of force distribution in the skull of a basal representative of the genus Pteronisculus during the hyoid retraction and tested it on a wooden skull model. We found a previously unrecognized mechanical connection between the expansion of the oropharyngeal cavity and the opening of the mouth. This mechanism may serve as an alternative to the opercular mouth-opening mechanism in recent bony fishes (Teleostei).

ABSTRACT The Tarrant Formation is stratigraphically the lowermost unit of the Upper Cretaceous Eagle Ford Group in Texas, U.S.A. and consists of sandstone formed near the East Texas Embayment of the Late Cretaceous Western Interior Seaway during the middle Cenomanian (ca. 95.78 Ma). We examined the taxonomic composition of vertebrate fossils from the Tarrant Formation based on specimens acquired through surface collecting and bulk sampling from three localities within Tarrant County, Texas. The specimens collected in this study, combined with the published record, reveal a diverse vertebrate assemblage that consists of a minimum of 24 vertebrate taxa, comprising at least eight chondrichthyans (Ptychodus, Microcarcharias, Cretodus, Cretoxyrhina, Cretalamna, and three species of Squalicorax), 12 bony fishes (Protosphyraena, Plethodidae, two pycnodonts, two pachyrhizodontids, two ichthyodectiforms, two enchodontids, and two indeterminate taxa), and four tetrapod taxa (e.g. two plesiosaurs, dolichosaurid, and pterosaur). These taxa occupy a variety of trophic regimes, including piscivorous, durophagous, and opportunistic or scavenging taxa. As the first collective survey of the vertebrates from the Tarrant Formation of Texas, this study offers new insights into the palaeoecology of this area during the middle Cenomanian, a critical point in the early development of the Western Interior Seaway and the East Texas Embayment.

Understanding the life-history patterns of fish species is crucial for effective fisheries management across temporal and spatial scales. This study investigates the population dynamics of fish inhabiting the shelf and break zone of the Gulf of Antalya, a highly oligotrophic region of the Mediterranean Sea that serves as a major spawning ground for various species, including fast-growing deep-sea fishes that reach maturity within 1-2 years. Population parameters, such as asymptotic length and growth rate, were estimated from length-frequency distributions using ELEFAN I in the FISAT programme. Multi-species analyses, particularly of dominant taxa, were performed to evaluate their interactions within the study area, while seasonality and environmental variability were also considered. A total of 165 demersal and some pelagic fish species were recorded throughout the year, of which 34 bony fish species were examined in detail. The results showed that population parameters varied significantly with both fish size and bottom depth. Along the shelf (10-75 m), asymptotic length (L∞) and growth rate (K) decreased with depth. At the shelf edge (200 m), L∞ remained high and K declined, whereas at the shelf break (300 m), L∞ decreased and K increased. Mortality rates [total mortality (Z) and natural mortality (M)] declined with increasing fish size, with medium-sized fishes exhibiting the highest Z values. The relationship between maximum age (tmax) and natural mortality (M) showed a significant correlation, particularly across size classes rather than depth strata. A comparative analysis with data from 524 publications indicated that population parameters are strongly influenced by geographical location within the Mediterranean, temporal variation (e.g., pre-2000s, 1990s-2000s, post-2000s) and west-east spatial gradients. This study also provides the first comprehensive population characteristics for four species - Epinephelus aeneus, Glossanodon leioglossus, Macroramphosus scolopax and Pagrus caeruleostictus - with important ecological and management implications.

Eonemachilus caohaiensis is a bony fish endemic to Guizhou Province, China. In this study, we report its complete mitochondrial genome for the first time. The circular mitochondrial genome is 16,570 bp in length and consists of 13 protein-coding genes (PCGs), two rRNAs, 22 tRNAs, and a non-coding control region (D-loop). The overall nucleotide composition is A: 30.84%,T: 27.02%,C: 26.00%, and G: 16.14%. Maximum likelihood phylogeny positioned E. caohaiensis as a sister taxon to Yunnanilus niger and E. longidorsali, supporting their classification within the genus Eonemachilus. These findings provide new insights into the phylogenetic relationships within the Nemacheilidae family.

The lipopolysaccharide (LPS)-induced inflammation model is widely used in mammalian studies but remains poorly investigated in a variety of fish species. We reproduce this model in rainbow trout, Oncorhynchus mykiss, a species of high economic value, to validate specific inflammatory biomarkers for reliably assessing the health and immune status of farmed fish. The inflammatory process, together with the effect of preconditioning, was modeled using two consecutive intraperitoneal injections of 300 and 600 µg LPS. We assessed innate immunity biomarkers, including the expression of inflammation-related genes (il1ß, il8), peripheral blood leukocyte profiles, serum bactericidal activity (SBA), and various serum and hepatic biochemical parameters. These parameters comprised the concentration of C-reactive protein (CRP, an acute phase protein), and the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione-S-transferase) measured at 24 and 96 h post-injection. In trout, LPS-induced effects involved the overexpression of pro-inflammatory interleukins (il1ß, il8), a left shift in white blood cells (characterized by a prevalence of immature neutrophils), and enhanced SBA. In contrast to warm-blooded animals, LPS challenge in trout did not appear to significantly elevate CRP levels or antioxidant enzyme activity. Further investigations in other fish species are needed to determine whether these are traits specific to trout or common to bony fish. Our findings provide a foundation for developing a biomarker panel suitable for the routine assessment of welfare, early detection of infection-associated inflammation in cultured fish, and the screening of the anti-inflammatory and immunostimulant activities of drugs and feed additives.

Τhe trophic ecology of Pterois miles in the Mediterranean Sea was performed by integrating data from stomach contents (SCA) and stable isotopes analyses (SIA), based on samples caught off the Greek island of Rhodes, SE, Aegean Sea, for the first time. This combined approach provides information on ingested (SCA) and assimilated (SIA) food and thus allows for the depiction of predator–prey relationships. Specimens of devil firefish, including both juveniles and adults (total length of analyzed specimens spanned from 11.40 to 31.50 cm), were collected from different sites around Rhodes. Their diet consisted of bony fish, cephalopods, crustaceans, and gastropods. The δ13C and δ15N values ranged from −18.0 ‰ to −14.4 ‰ and from 7.2 ‰ to 9.2 ‰, respectively. SIA data allowed for the estimation of the trophic position of devil firefish from Rhodes Island, which showed a mean value of 3.1 ± 0.6 and confirms that the species primarily relies on a benthic baseline. Further, our isotopic values approach those obtained in North Carolina and Bermuda, confirming its role as a mesopredator in the Mediterranean benthic food webs. Although preliminary, such results can provide an important baseline for future investigations on the species and the potential impact on the Mediterranean food webs.