Establishment of a dorsal fin cell line from largemouth bass (Micropterus salmoides) and its apoptosis induced by MSRV

Thermal analysis and structural optimization of microchannels of bionic dorsal fin structure using multi-objective genetic algorithm

A new freshwater ricefish was collected recently from northern Taiwan, which has been identified as a species new to science. The new species, Oryzias cabaranensis sp. nov., can be well distinguished from other congeners by the following unique combination of features: (1) fin-ray counts: dorsal-fin rays 6; anal-fin rays modally 17; pectoral-fin rays 9–10; (2) body compressed laterally, body depth at pelvic origin 20.9–23.3 (22.3), body depth at anal fin origin 17.2–20.1 (18.8); (3) the dorsal-fin origin inserted almost at the vertical of 12th anal-fin rays; and (4) specific coloration: Body translucent, light creamy yellowish, a dotted, longitudinal black line. Belly wall, peritoneum slivery, somewhat subrectangular. Operculum and pre-pectoral region slivery. Eye light bluish. Caudal fin unmarked. Pelvic and anal fins with tiny melanophores. The diagnostic characters and a comparison with related species will also be provided.

Limbs exhibit adaptive differentiation along their dorsal-ventral (DV) axis, determined by the dorsal expression of the LIM homeobox gene Lmx1b. The paired appendages (i.e. the pectoral and pelvic fins from which limbs evolved) arose in an early jawless ancestor via co-option of a midline-fin genetic program including modules for anterior-posterior (AP) and proximal-distal (PD) patterning. Unlike the AP and PD axes, median fins lack an unambiguous DV axis, leaving the origin of this DV pattern in paired appendages unresolved. Here, we describe Lmx1b expression in the posterior midline fins of cichlids, sturgeons, catsharks and lampreys, revealing an ancestral role for this gene predating the origin of paired appendages. In median fins, Lmx1b activation depends on shh from the ZPA, whereas in paired fins it relies on ectodermal wnt signaling, indicating the evolution of novel regulatory inputs for dorsal patterning. We observe that ephA4b, a putative Lmx1b target, is co-expressed with Lmx1b in dorsal pectoral and posterior midline fins and downregulated alongside Lmx1b, suggesting a role in both fin types related to axon guidance. We propose that novel regulation drove the repurposing of Lmx1b from posterior to dorsal fin determinant, with co-option of conserved downstream targets. Altogether, our findings demonstrate that the DV axis of paired appendages represents an evolutionary innovation arising from the integration of ancestral midline fin and flank determinants with novel regulatory inputs.

Characidium tupi, a new species from rivers draining the southern portion of the Northeastern Mata Atlantica Freshwater Ecoregion, is described. The new species can be distinguished from all congeners by its colour pattern, including 7-14 dark bars enlarged and more conspicuous on their ventralmost portion, resulting in a longitudinal series of conspicuous dark blotches positioned around the midlateral line of the body, and the presence of a conspicuous 3-shaped black band approximately at the midlength of the caudal-fin rays. In addition, the new species differs from most congeners by having a dark band below the midlength of the dorsal-fin rays initiating on the third or fourth branched rays and isthmus, and large areas around the pectoral-fin bases scaleless, but with a broad central patch of scales. Both sexes possess a vestigial swimbladder, which was slightly longer in the males examined. Species delimitation analyses were based on the mitochondrial cytochrome c oxidase subunit I marker and the genetic distances obtained reinforce the recognition of C. tupi as a distinct species, with divergences exceeding 6% in relation to its closely related species.

The new estuarine goby Eugnathogobius ganuensis n. sp. is described from 5 specimens (4 males: 27.0–31.5 mm standard length; 1 female: 27.5 mm standard length) collected from a small ditch in the lower reach of the Terengganu River basin, east coast of Peninsular Malaysia. The new species is easily distinguished from other congeners, except E. kabilia, by the following a combination of characteristics: 16 segmented caudal-fin rays; 30 or 31 longitudinal scale lows; high first dorsal fin (especially in males); no head pores; shoulder with oblique black band; transverse black markings on each scale; paired black blotches on caudal-fin base; and distinct black dots on upper caudal fin. Although E. kabilia is very similar to the new species, the latter has a shorter jaw in males (well-extended in the former), high first dorsal fin (low), first dorsal-fin second spine length > 16.8% of standard length (<13.6%), throat yellowish in the fresh condition (whitish), and a yellowish second dorsal fin (reddish in males of E. kabilia). Because the type locality of the new species is clearly not a natural environmental feature and no salinity during the low tide, despite being included in the tidal area, the true habitat is suggested as being the upper reaches of estuarine areas.

Abstract The erosion of bed materials and coal ash on water‐cooled walls presents a persistent technical challenge in circulating fluidized bed boiler systems, manifesting as increased frequency of unplanned shutdowns and elevated maintenance requirements. Traditional metal anti‐wear devices, due to inherent structural limitations, struggle to achieve optimal coordination between velocity and pressure gradient fields, making them prone to erosion and limiting their overall wear resistance. This study proposes bionic anti‐wear devices inspired by squid fin and shark dorsal fin. The experimental and simulation results show that bionic devices can optimize the coordination between the velocity and pressure gradient fields. Compared to the traditional right‐angle triangular device, the shark dorsal fin‐inspired device reduces the windward surface area by 3.25%, maximum pressure coefficient by 50%–60%, and the erosion rate by 93.55%. This study provides an innovative approach for developing next‐generation anti‐wear devices with enhanced wear resistance.

ABSTRACT Stocking fish is a common practice in fisheries management, particularly for species of high conservation value or economic importance. Despite its widespread use, systematic evaluation of fish stockings remains scarce. This includes non‐native species such as rainbow trout ( Oncorhynchus mykiss ), which are intensively stocked into European water bodies for recreational angling. Rainbow trout used for stocking into the German River Inn are sourced from various hatcheries, likely contributing to differences in their physical condition which may affect post‐stocking survival. This study provides a baseline assessment of the physical condition, focusing on morphometric traits and external injuries, of rainbow trout prior to stocking in this large alpine river. We analyzed 150 individuals from five aquaculture facilities using morphometric measurements and standardized injury assessment protocols. Rainbow trout showed a high level of morphometric plasticity associated with their origin. All examined fish had visible external injuries, with the most frequent ones being tears and amputations on the caudal and dorsal fins, as well as scale loss. Up to 11 of 22 possible injury types were identified in the most severely affected individuals, and specific external injury patterns could be related to specific hatcheries. These findings offer important baseline data on the physical condition of stocked rainbow trout and provide a foundation for interpreting future studies on their performance in the wild.

A single individual (2318 mm total length) of Strophidon tetraporus Huang et Liao, 2020 was collected from Heuksan-myeon, Sinan-gun, Jeollanam-do, Korea, in December 2023. This species is characterized by the following morphological traits: elongated body, biserial maxillary and dentary teeth, four infraorbital pores, 195 vertebrae (8 predorsal, 79 preanal), and continuous dorsal, anal, and caudal fins. Genetic analysis of the cytochrome oxidase subunit I ( COI ) sequences confirmed its identity, with only 0.02–0.03 percentage-point divergence from the type specimens of S. tetraporus . This record represents the first verified occurrence of S. tetraporus in Korean waters and extends the species’ distribution to its northernmost limit.

ABSTRACT This study describes new hybodontiform remains from the Cenomanian Alcântara Formation, São Luís Basin, northeastern Brazil. The fossil material includes cephalic spines, dorsal fin spines, and oral teeth attributed to three hybodontiform families: Distobatidae, Hybodontidae and Lonchidiidae. The Distobatidae record is substantiated by both the newly described Distobatus nutiae identified in this study and the previously reported Aegyptobatus cf. kuehnei from the region. Diagnostic cephalic spine morphologies (‘T-shaped’ and ‘arrow-shaped’) support the attribution to Hybodontidae and Lonchidiidae, respectively. The occurrence of Distobatidae in the Alcântara Formation, together with records from other Cretaceous deposits in northeastern Brazil and North Africa, suggests possible faunal affinities among freshwater and marginal marine hybodontiforms of northern Gondwana. These findings provide new insights into the paleobiogeographic links between South America and Africa during the early stages of South Atlantic opening.

This study examined aspects of the biology of Oreochromis niloticus, focusing on sexual dimorphism within the Qua Iboe River Estuary, Nigeria, from April 2021 to March 2022. A total of 1,267 specimens were obtained from artisanal fishers using various mesh sizes of gill nets and cast nets. Sex identification was based on genital papilla morphology, with males possessing a single opening and a distinct genital papilla, while females exhibited two openings. Additional dimorphic features included pointed dorsal and anal fins in males and rounded, more expanded fins in females. The overall population consisted of 689 males (54.38%) and 578 females (45.62%), yielding a male–female ratio of 1:0.83, which significantly deviated from parity (χ² = 87.299, df = 1, P < 0.05). Biometric characteristics showed minimal size dimorphism. Males recorded a mean total length of 12.08 ± 0.157 cm and mean total weight of 37.77 ± 1.10 g, while females measured 12.05 ± 0.11 cm and 35.66 ± 0.903 g, respectively. The condition factor (K) was slightly higher in males (2.14 ± 0.04) than in females (2.04 ± 0.03), indicating good physiological status across the population. Length–frequency distribution revealed that most individuals occurred within the 10–14 cm size class, suggesting strong recruitment, continuous breeding activity, and a stable, thriving stock. The findings provide essential baseline information on sexual dimorphism, population structure, and length–weight characteristics of O. niloticus in the Qua Iboe River Estuary. These insights are valuable for improving local aquaculture practices, enhancing broodstock selection, supporting sustainable fisheries management, and guiding conservation strategies for the species in Nigerian estuarine ecosystems.

Using drone-based infrared thermography for monitoring vital signs in dolphins.

Role of the cymothoid isopod, Nerocila bivittata in spread of Photobacterium damselae subsp piscicida to Thinlip mullet (Chelon ramada).

Metal and metalloids in the longsnout seahorse Hippocampus reidi Ginsburg, 1933 across three coastal Brazilian bays.

The aim of the study is to investigate the effect of chitosan-β-cyclodextrin complexes with immobilized levofloxacin on some microbiological parameters of cut wounds and the large intestine of catfish. The experiment was conducted at the Progressive Biotechnologies in Aquaculture Research Laboratory of the N.I. Vavilov Saratov State University of Genetics, Biotechnology and Engineering. The course of the inflammatory process and the effectiveness of cyclodextrin-based treatments were characterized by determining the total microbial count of cut wounds, as well as the total microbial count and the number of lactic acid bacteria in the large intestine of juvenile African labyrinth catfish – Clarias gariepinus. Five groups of fish with cut wounds of the skin were formed (n = 10): 1st control, in which the fish received a regular balanced feed; 2nd control with a model of digestive disorders and intestinal dysbiosis; experimental groups 1, 2, and 3 received treatment with 20 %, 15, and 10 % levofloxacin, respectively. The fish received this treatment three times daily with their feed for 7 days. Wounds were created by making 2-cm incisions in the dorsal muscles near the dorsal fin. The wound surface was washed with sterile cotton swabs. The contents of the large intestine were extracted under sterile conditions after fish necropsy. The total microbial count (TMC) and lactic acid bacteria were determined by serial dilution and colony counting after culture. Chitosan-β-cyclodextrin complexes with varying levofloxacin concentrations were equally effective in healing catfish incision wounds, as demonstrated by a reduction in the total microbial count on the wound surface compared to untreated groups. The sample containing 20 % levofloxacin demonstrated the greatest inhibitory activity against intestinal microflora at the end of the study, while the proportion of lactic acid bacteria in the TMC in the experimental groups increased at the end of the study compared to the start of treatment with the treatment complexes.

This study reports the first records of Sphyraena arabiansis in the Korean waters. The two specimens were collected from the coastal waters of Yeosu (1164 mm TL) and Jeju Island (1187 mm TL), Korea, on 31 July and 24 October 2025, respectively. This species is characterized by the posterior end of the upper jaw not extending vertically below the eye, the lateral line curving anterior to the first dorsal fin, the lower part of the branchiostegal membrane being whitish, dark transverse bands on the upper side of the body crossing the lateral line but not reaching the abdomen, no black spots on the body side, 118 and 121 lateral line scales, and 14 scales below the lateral line. To confirm the accuracy of species identification, the mitochondrial DNA cytochrome c oxidase subunit I sequences were obtained from the samples and compared with those of seven sphyraenid species recorded in the NCBI GenBank database. As a result, they matched well with S. arabiansis but differed from those of S. barracuda. The new Korean name, “Jjal-beun-ip-keun-kko-chi-go-gi,” is proposed for the species.

This study investigates the influence of fin morphology on predator-prey dynamics among selected fish species in Kwatan Giwa River, Niger State, Nigeria. A total of 192 fish samples representing eight species were collected biweekly from June to August 2024 at the Kwatan Giwa River fish landing site. Fish species were identified using standard taxonomic guides. Morphometric measurements of tail, pectoral, dorsal, and ventral fins were recorded using vernier calipers. Gut content analysis was conducted following modified Waraniak et al., (2019) procedures to determine dietary components and establish trophic relationships. Data were statistically analyzed to assess variations in fin structures and their ecological implications. The findings revealed significant interspecific variations in fin morphology. Species like Tilapia zilli and Auchenoglanis biscutatus possessed higher pectoral and ventral fin lengths, facilitating better maneuverability and habitat adaptability. Conversely, Siluranodon auritus exhibited consistently low fin measurements, indicating limited mobility and habitat specialization. The gut analysis revealed that Clarias gariepinus, identified as a piscivorous predator, had gut contents containing scales and remains of Tilapia spp, juvenile Synodontis, Labeo senegalensis, and Marcusenius senegalensis. In contrast, Tilapia spp, Labeo senegalensis, Auchenoglanis biscutatus, and Siluranodon auratus showed no fish remains in their guts, indicating non-piscivorous diets. The study successfully highlighted the relationship between fin size and predation strategies among selected fish species in the study area. However, Efforts should be made to protect the natural habitats of these fish species from degradation due to pollution, deforestation, and human encroachment.

ABSTRACTDuring their development, fish pass through a series of developmental processes advancing, for example, their physiological and locomotive abilities. In particular, many marine fish larvae often hatch at an (semi‐) embryonic developmental stage, and existential processes, such as digestion and respiration, and structures, such as muscle and skeleton, must form and/or change during the larval development. In this study, we analyzed the gene expression of factors associated with myogenesis, skeletogenesis, and growth within the different larval life stages of Atlantic herring. We evaluated these results in relation to length and stage ratio and performed histological analysis of cross‐sections of herring larvae in different stages. Overall, the length per stage ratios showed that there are two major growth periods in larval herring development, the first occurring during the dorsal fin development phase and the second during the transition from caudal fin to pelvic fin development phase. This is consistent with the histological analysis, as an increase in muscle fibers was observed in both phases. The gene expression data also showed that factors responsible for muscle cell lineage determination and fiber development were highest before a period with increased growth. Combining our results with other studies on skeletogenesis, organogenesis, and the development of neural and sensory systems in herring, it becomes evident that other energetically costly developmental processes tend to occur in periods when growth is less prominent. It can therefore be concluded that growth and developmental priority periods alternate during larval development.

The orangefin barb, Enteromius eutaenia - a small-sized smiliogastrin barb characterised by orange/yellow fins, a thickened and serrated last unbranched dorsal-fin ray, a dark mid-lateral stripe and a sheath of enlarged scales at the base of dorsal fin - is considered widely distributed across southern Africa. Distinct phenotypic groups suggest unrecognised species-level diversity, but taxonomic progress has been limited by the poor knowledge of true E. eutaenia. Here, we re-examine the type specimens of E. eutaenia and a collection of E. eutaenia-like fishes from the Cunene River system to clarify their taxonomic status, using morphometric/meristic data and mitochondrial cytochrome c oxidase I (COI) sequences. Based on these data, we redescribe E. eutaenia and describe two new species: Enteromius bieensis sp. nov. (found in sympatry with E. eutaenia in the Upper Cunene River close to Huambo, situated on the Bié Plateau, Angola) and Enteromius ruacanaensis sp. nov. (found in the Lower Cunene River, Ruacana Gorge, below the Ruacana Falls at the border between Namibia and Angola).

In this study, we describe a newly recognized croaker (Sciaenidae), Johnius javaensis sp. nov. based on five specimens (87-121 mm in standard length) from the southern coast of Java, Indonesia. Specifically, taxonomic reassessment of sciaenids collected from fish markets on the islands of Java, Bali, and Lombok of Indonesia has revealed that specimens previously identified as Johnius heterolepis represent this new species. Johnius javaensis sp. nov. is characterized by five vesicular mental barbels on the chin, 30-32 dorsal-fin rays, seven or eight scale rows below the lateral line; 11 or 12 lower gill rakers, 11 or 12 swim-bladder appendages, and ventral margin of the sagitta head expanded into a distinct convexity. Historically, four Johnius species (J. amblycephalus, J. fuscolineatus, J. macropterus and J. mannarensis) were reported to have one mental barbel on the chin. The new species is readily distinguished from all other 33 described Johnius species by possessing five vesicular mental barbels on the chin. A phylogenetic analysis of 21 Johnius species based on the 521-bp COI gene confirms that the new species is placed as a sister species of J. macropterus, based on an average of dissimilarity 8.16%.