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Aquatic ecosystems are increasingly affected by anthropogenic pollution, including heavy metals like mercury, which accumulate in organisms and cause harmful effects. At the same time, human activities such as industrial operations and the use of electric power lines also alter the magnetic background in natural water bodies. However, the interaction between mercury exposure and magnetic fields remains poorly understood. This study aimed to investigate the combined effects of mercury and magnetic fields on the digestive enzyme activity of common carp (Cyprinus carpio), focusing on the relevance of magnetic fields due to their increasing presence in industrialized environments. Two groups of fish were fed diets with low (0.02 mg/kg) or high (0.27 mg/kg) mercury content for 6 months and exposed to extremely low-frequency magnetic fields or hypomagnetic conditions. Results showed significant differences in mercury accumulation between groups, with higher levels in carps fed with high-mercury content diets. These fish also exhibited increased body length and weight compared to those on a low-mercury diet. The amylolytic activity (total activity of enzymes hydrolyzing starch: α-amylase, glucoamylase, and maltase) and proteolytic activity (total activity of serine proteinases) in the fish intestine were assessed. Magnetic exposure had contrasting effects on enzyme activity, depending on mercury levels in the diet. Fish fed the low-mercury diet exhibited decreased amylolytic activity following magnetic field exposure, while fish on the high-mercury diet showed increased activity. Proteolytic activity followed a similar pattern, with opposite effects observed between the two dietary groups. These findings suggest that mercury accumulation alters the biological response to magnetic fields, possibly through compensatory biochemical mechanisms. Understanding the interactions between toxic substances and magnetic fields is critical for improving environmental risk assessments. [ABSTRACT FROM AUTHOR]

To explore the morphological differences among different geographic populations of Gymnocypris chilianensis, 29 measurable traits and 13 landmarks on 191 individuals of 10 geographic populations were collected from three different inland water systems, i.e., Shiyang River, Heihe River, and Shule River, in Qilian Mountains, China. Multivariate statistical methods were used to compare morphological differences among the populations, such as principal component analysis, cluster analysis, discriminant analysis, and visual analysis of landmark data. The results showed that: (1) There were significant morphological differences between groups of G. chilianensis. The Shiyang River basin differs significantly from populations in the other two basins. (2) The inter-population differences were mainly reflected in the length of the trunk and tail, and the difference between trunk and caudal fin had the most obvious characteristics, proving the tail being the main direction of variation. This research provides an effective theoretical basis for the fine management and accurate protection of G. chilianensis germplasm resources. [ABSTRACT FROM AUTHOR]

To protect the germplasm resources of Gymnodiptychus dybowskii (Kessler, 1874), a species endemic to Xinjiang, the key stages of embryonic development of G. dybowskii were studied. From May to July 2021, the artificial breeding of G. dybowskii was carried out at the fish breeding station of the Kenswart Water Conservancy Project. The embryos and early larvae were obtained using temperature promotion, water stimulation, hormone induction, and dry insemination techniques. their development process was observed, and morphological characteristics of each developmental stage were recorded. The results showed that the mature oocyte was round, heavy, and light yellow, with an egg diameter of (2.32 ± 0.21) mm. The fertilized egg was slightly viscous, and the viscosity disappeared after water absorption. Under the temperature of 15.6-17.7 °C (16.23 ± 0.52) °C, the embryonic development of G. dybowskii lasted for 142 h and 33 min and went through 7 stages of fertilization, cleavage, blastula, gastrula, neurula embryo, organ formation, and membrane hatching, with a total of 26 periods. The membrane broke after 2376.724 °C-h. The embryonic development of G. dybowskii follows the rule of freshwater bony fish, but it differs from other Schizothorax species in the muscular effect period and membrane emergence mode. In addition, differences in hatching water temperature among different geographic populations lead to differences in embryo development duration and accumulated temperature, which further proves that G. dybowskii is highly adaptive to the ecological environment of its habitat water, and these characteristics together constitute its survival and reproduction strategy in the natural environment. In this study, through the artificial breeding experiment of G. dybowskii, the characteristics of its embryonic development were explored, which laid the foundation for the cultivation of unique fish seedlings, enriched the early life history data of G. dybowskii, and further provided basic data for its resource protection. [ABSTRACT FROM AUTHOR]

Simple Summary: A comprehensive report about the embryonic development of Cirrhinus mrigala is portrayed. Cirrhinus mrigala embryonic development is classified into 22 stages. A time-lapse imaging technique was utilized for a better understanding and display of the results. The current findings will provide profound insights into future research endeavors and the large-scale seed production of C. mrigala.Cirrhinus mrigala is an important edible fish with a significant aquaculture contribution in Southeast Asian countries. The current study aims to enhance our understanding of the developmental biology of Cirrhinus mrigala, which is crucial for implementing sustainable fish farming practices. To induce spermiation and ovulation in Cirrhinus mrigala brooders, the synthetic hormone Ovaprim® (GnRH + dopamine inhibitor) was administrated as a single injection dose of 0.2 mL/kg to males and 0.4 mL/kg to females. After induction, the fish spawned, and the eggs produced were fertilized artificially and cell division commenced successfully. The characteristics of each larval developmental stage were closely observed and recorded using a time-lapse imaging technique. The fertilized eggs were spherical, demersal, and non-adhesive throughout their incubation period. The spawned eggs ranged in diameter from 2.1 mm to 2.13 mm and possessed circular yolk sacs. The gastrula stage initiated approximately 4 h after fertilization, with 25% of the yolk sphere covered by blastoderm, reaching 75% coverage at the end of the gastrula stage, approximately 6 h post fertilization. Organogenesis was marked by the formation of notochord and the visibility of rudimentary organs such as the heart, eyes, and gills, followed by tail movement, which was observed at the time of hatching. Compared to other cyprinid fishes, C. mrigala exhibited distinct features at certain stages of embryonic development. Blood circulation was observed to start at the onset of hatching. The lengths of the newly hatched larvae ranged from 2.9 to 3.2 mm, smaller than other reports on induced breeding in carps. The findings of the present study provide a detailed reference for the embryonic development of C. mrigala, which will assist its future research endeavors and large-scale seed production for sustainable aquaculture. [ABSTRACT FROM AUTHOR]

The introduction of non-native fish species poses a significant threat to biodiversity. In Spain, the common carp Cyprinus carpio (Linnaeus, 1758) and the bleak Alburnus alburnus (Linnaeus, 1758) are both established and sometimes co-occurring non-native species. Here, we investigated the trophic ecology of these species using an integrative approach, combining dietary and stable isotope analyses, to understand seasonal variations in their feeding ecology and potential niche overlap. We found a variable pattern for the gonadosomatic index of the two species in spring and autumn, suggesting the occurrence of extended reproductive periods for both A. alburnus and C. carpio. The gut content and isotopic niche analyses showed seasonal niche shifts, as well as interspecific niche partitioning and potential feeding competition. Notably, we found remains of small fish in the gut of both species and one entire individual of Gambusia holbrooki (Girard, 1859) in the carp gut, highlighting the potential of both species to prey also upon native fish fry or juveniles. Moreover, A. alburnus showed an ontogenetic shift toward prey from higher trophic levels and from the littoral/benthic environment, while C. carpio showed an increase in the proportion of prey from the pelagic environment with size. [ABSTRACT FROM AUTHOR]

The paper presents a redescription of the parasitic nematode Philometroides strelkovi (Chromadorea: Dracunculoidea) based on the new morphometric data. New hosts from the Cyprinidae family (Rhodeus sericeus, Hemiculter leucisculus, Hemibarbus labeo) and locality—the Luchegorsk reservoir belonging to the Amur River basin (Pozharsky district of Primorsky Krai in the south of the Russian Far East) have been described. For the first time, sequences of the 18S rRNA marker gene have been obtained for P. strelkovi. On the basis of genetic data, we performed phylogenetic reconstruction and showed the clustering of P. strelkovi, separate from the sister species P. moraveci, confirmed by high statistical support at branching nodes and the size of genetic distances—0.11–0.56% between P. strelkovi and other representatives of the genus, along with intergeneric divergence of >4%. In the light of new molecular data, the question of the artificiality of the genera Philometroides and Philometra is raised. [ABSTRACT FROM AUTHOR]

The glyphosate herbicide is a pesticide widely used in the world and can contaminate soil, air, and water. The objective of this work was to evaluate the toxicity of a glyphosate‐based herbicide (GBH) in zebrafish (Danio rerio). Fish were exposed to different concentrations of GBH (0, 50, 250, and 500 µg/L) for 96 hours. Brain, liver, and blood were collected for biochemical and genotoxicity analyses, and behavioral tests were performed. The results showed that there was a reduction in the activity of the antioxidant enzymes of catalase (CAT) and glutathione‐S‐transferase (GST) in the liver at all concentrations and at the highest concentration in the brain. There was also a reduction in lipid peroxidation in the liver at all concentrations of glyphosate. There was an increase in micronuclei in the blood at the 500 µg/L concentration. However, the count of nuclear abnormalities showed no differences from the control. Interleukin‐1beta (IL‐1β) generation was inhibited at all concentrations in the liver and at the highest concentration in the brain. No significant differences were found in the behavioral test compared to the control. The results showed that acute exposure to GBH promoted an inflammatory event, which reduced the efficiency of antioxidants, thus producing a disturbance in tissues, mainly in the liver, causing immunosuppression and generating genotoxicity. [ABSTRACT FROM AUTHOR]

The additional record of Hypselobarbus kushavali is reported from Thunga River, Karnataka, India and a new species of Hypselobarbus from Bhadra River, Karnataka is described herein. Hypselobarbus arunachalami sp. nov. is diagnosed from all its congeners in the genus by having fewer lateral-line scales and fewer circumferential scale rows [ABSTRACT FROM AUTHOR]

Leader–follower modalities and other asymmetric interactions that drive the collective motion of organisms are often quantified using information theory metrics like transfer or causation entropy. These metrics are difficult to accurately evaluate without a much larger number of data than is typically available from a time series of animal trajectories collected in the field or from experiments. In this paper, we use a generalized leader–follower model to argue that the time-separated mutual information between two organism positions can serve as an alternative metric for capturing asymmetric correlations that is much less data intensive and more accurately estimated by popular k-nearest neighbor algorithms than transfer entropy. Our model predicts a local maximum of this mutual information at a time separation value corresponding to the fundamental reaction timescale of the follower organism. We confirm this prediction by analyzing time series trajectories recorded for a pair of golden shiner fish circling an annular tank. [ABSTRACT FROM AUTHOR]

Simple Summary: Myxozoa is an important metazoan parasite, with approximately 2600 species reported around the world. However, their diversity is still largely underestimated, particularly for those of the Culters, where only 15 species have been previously reported in China. Thus, an investigation into the diversity of myxozoans in Culters was conducted, and a new species belonging to Myxobolus was found. Through comprehensive morphological comparisons and molecular analyses with closely related species, we designated it a new Myxobolus species and named it Myxobolus darbryi n. sp. Culters are a popular and economically important carnivorous freshwater fish, widely distributed in rivers, lakes, and reservoirs in China. An investigation of Myxozoa was conducted to enhance the understanding of Myxozoan diversity in Culters in China, as only 15 Myxosporean species have been previously reported in 6 Culters species. A new species with typical Myxobolus characteristics was discovered exclusively in the gills of Chanodichthys dabryi, Bleeker, 1871, and no other species were found in other Culters fish or organs. The new species elicited whitish plasmodia in the serosa layer of the gill arch, with no distinct inflammatory reaction observed. This species is morphologically different from all reported Myxobolus spp. from Culters, differing in plasmodium and spore size, as well as the coils of polar filaments. Molecular analysis further supports that it does not match any sequences available in GenBank. Therefore, we identified it as a new species and named it Myxobolus dabryi n. sp. [ABSTRACT FROM AUTHOR]

The present study was conducted to document the fish fauna and their IUCN status of Chessore sub-division of Shamator, Nagaland for a period of one year, from May 2023 - April 2024 covering the targeted areas. The survey reveals the presence of 20 species belonging to 5 orders, 9 families and 15 genera. The order Cypriniformes dominanted with 14 species while Anabantiformes, Perciform and Synbranchiformes with 1 species each is the least common. According to IUCN Red-list and habitat studies during different seasons, one species belonging to family cyprinidae is under IUCN-NT category, five species belonging to cyprinidae, channidae and cobitidae is under IUCN-VU while the rest falls under IUCN-LC and Data deficient (DD) category. A primary threat to the fish biodiversity in study area is due to anthropogenic activities and environmental changes. [ABSTRACT FROM AUTHOR]

Present study provides data of organochlorine pesticides (DDT, HCH) and polychlorinated biphenyls (28, 52, 155, 101, 118, 143, 153, 138, 180, 207 congener) content in six carp fish from Lake Khanka. Organochlorine compounds are found in all studied samples. HCHs isomers were dominant, constituting on average 70% of all pesticides detected. α-HCH content varied from 8 to 95%. Among DDTs, o,p’- and p,p’-DDE were predominant (on average 10–100 and 15–100%, respectively). PCBs content in all fish samples was primarily presented by low-chlorinated 28 and 52 congeners. Detected isomers evidence on the long-term pollution of Lake Khanka by persistent organic pollutants. Compare to southern China and Croatia, fish from Lake Khanka showed significantly higher levels of accumulation of HCH and lower levels of DDT and PCB. When comparing the data with the requirements of regulatory documents in Russia and China, no cases of exceeding maximum permissible concentrations were identified.

Fishes are found in different lentic and lotic aquatic ecosystems. Determining the composition of fish communities is a crucial component of water quality evaluations and conservation strategies in flowing rivers. The present study is carried out to investigate fish species diversity, richness, and abundance in two second-order streams: Gereb Tsedo (GTS) and Elala in the Tekeze sub-basin. We collected fish with backpack electrofishing during August and December 2013 and March 2014. Fish species richness and the total number of species per stream and per microhabitat were calculated for each stream. Species diversity for each site was calculated using the Shannon index of diversity using the standard formula H’ = –Σpi ln (pi). Diversity data among habitats and streams were compared using one-way analysis of variance (ANOVA) and Tukey post hoc comparisons, using the statistical software package STATISTICA 11. A total of 6,554 specimens representing four species: Garra blanfordii, Grra ignestii, Garra dembecha and Garra aethiopica, were caught. They are all indigenous riverine fish species of the family Cyprinidae. Fish abundance was significantly higher in GTS than Elala stream (t-test, t = 1.444, df = 3, p < 0.05). Across the two streams, the overall relative fish abundance was higher in pools, with 53%, followed by runs and riffles with 35% and 12%, respectively. Garra blanfordii was dominant in pools while G. aethiopica was the least dominant. Stream and habitat types were likely the more important driving factors behind the observed patterns of diversity, although the impact of other, not evaluated variables cannot be excluded. Most likely, the observed patterns do not represent a signature of fish dispersal limitation given that almost all species were widely distributed across the study area.

The article explores the icthyofaunal diversity in selected lakes of Somwarapete taluk of Kodagu district in Karnataka, India. The study calculates the diversity of fishes and distribution of fish species and evaluates the endemism of the fishes. It identifies fish abundance belonging to different genera and families including Cyprinidae, Channiadae and Claridae taxa.

The primary objectives of this study were to advance understanding of the morphological intricacies exhibited by the endemic fish species Delminichthys ghetaldii, commonly known as the Trebinje minnow, and to determine intraspecific morphological variability. The study involved the examination of 76 mature specimens collected since 2018 from five distinct karst fields located within the Dinaric region of Eastern Herzegovina, Bosnia and Herzegovina. A comprehensive analysis of 22 morphometric and 8 meristic characteristics was conducted to unravel the underlying patterns of variation. Discriminant function analysis was employed for the thorough investigation of the morphometric traits, whereas canonical correspondence analysis was applied to scrutinize the meristic traits. The discriminant function analysis yielded noteworthy outcomes, revealing substantial differentiations across 17 morphological characteristics within samples from diverse karst fields. Furthermore, it revealed notable dissimilarities in four morphometric characteristics when data including both male and female specimens were examined. Remarkably, these analyses showed that Delminichthys ghetaldii specimens inhabiting the Popovo karst field exhibit significant morphological disparities compared to those in the other fields. Conversely, individuals from the Fatničko karst field showed a pronounced morphological affinity with their counterparts from the Mokro karst field. Intriguingly, a resemblance in morphometric characteristics was noted between Delminichthys ghetaldii inhabitants of the Dabarsko karst field and those from the Ljubomirsko karst field. The assessment of osteological meristic characteristics across samples from the five distinct karst fields, as well as the differentiation between male and female specimens, did not reveal any statistically significant distinctions. [ABSTRACT FROM AUTHOR]

The hemicultrine fishes are a group of small‐sized cyprinids, widely distributed but endemic to East Asian rivers and lakes. Till now, the taxonomic boundaries and relationships within this group remain poorly explored. In the present study, we study the phylogeny of this group, providing suggestions for classification of the hemicultrine group. Using two mitochondrial and three nuclear genes, and samples representing all genera, our results showed that the group consists of seven major lineages, of which four (Hemiculterella, Hainania, Pseudolaubuca, and Anabarilius) were monophyletic and three (Hemiculter, Toxabramis, and Pseudohemiculter) were not. Based on the phylogenetic tree, we redefined the genera. We revive the genus Siniichthys, which has three species, Siniichthys bleekeri, Siniichthys lucidus, and S. varpachovskii, that were previously treated as members of the genus Hemiculter but showed distant relationships to the genus Hemiculter in our phylogenetic tree. With the new results, a diagnostic key for clades of the hemicultrine group is provided. Furthermore, we provide more detailed information on diagnostic features of the recently described species Hemiculter yungaoi (Vasil'eva et al., 2022). This work will facilitate future systematic studies, pave the way for evolutionary studies, and provide valuable information for the urgent conservation of hemicultrine fishes. [ABSTRACT FROM AUTHOR]

Three species of subfamily Cultrinae currently live in Korea, but Erythroculter erythropterus has been introduced into the Nakdonggang River and has taken over the habitat, reducing the habitat of Culter brevicauda. Only the endangered species C. brevicauda still lives in the Yeongsangang River, and it is necessary to be careful not to introduce E. erythropterus in the future. Hemiculter eigenmanni is also found throughout the country. In order to effectively manage and conserve the species in its various habitats and against invasions, this study was initiated. The ultrastructure of the egg envelopes of three species of Cultrinae inhabiting the Geumgang and Yeongsangang Rivers—E. erythropterus, C. brevicauda, and H. eigenmanni—were observed. It was found that the zona radiata of the egg envelopes of all three species were divided into two layers, an outer and inner layer, with the outer surface having a non-structural form. This form is characteristic of fishes with muddy, stagnant habitats or spawning grounds. The number of pore canals on the surface of the egg envelopes was 83 for E. erythropterus, 75 for C. brevicauda, and 58 for H. eigenmanni per 10 μm2, and the thickness was 7.89 ± 0.34 μm, 12.27 ± 0.46 μm, and 7.42 ± 0.24 μm, respectively. The shape of the micropyle demonstrated a funnel shape narrowing toward the inner diameter in all three species, and the size of the inner diameter was 6.62 ± 0.29 μm in E. erythropterus, 4.19 ± 0.39 μm in C. brevicauda, and 3.98 ± 0.46 μm in H. eigenmanni. The differences between species were identified in the number of pore canals, thickness, and micropyle inner diameter of egg envelopes, which were species-specific. Our study reveals a morphological mechanism in the egg envelope that prevents the formation of interspecific hybrids, and these features can be taxonomic traits that clarify species names. It also provides useful data for the production (breeding) of the second generation in aquaculture. [ABSTRACT FROM AUTHOR]

A diverse range of freshwater habitats may be found in the Mediterranean basin, which is also home to a rich variety of cyprinids, including the genus Barbus. Numerous factors pose a threat to this diversity, increasing the susceptibility of fish to parasitic infections. The current study attempted to investigate the Barbus's parasitic variety. In Morocco, publications concerning this subject are rare and limited to certain taxa and specific biogeographic zones. Patrick Berrebi (1983) is the first researcher to report the infestation of three species of Moroccan barbel from the Atlantic slope, by Myxobolus sp., whereas, El Gharbi and other collaborators (1994), based on morphological criteria, were able to describe fifteen new species of Monogeneans, in fifteen species of the genus Barbus. Then in recent years, Rahmouni and other colleagues (2017) identified four new species of Dactylogyrus in the gills of three species of Luciobarbus, originally collected by Heckel (1843) in different watersheds in northern Morocco. In Algeria, Meddour (2009) in his investigation of the fish parasitofauna of Lake Oubeira, was able to discover two cestodes and an acanthocephalan. While in the south of France, Alain Lambert (1977) identified two species of Monogenes among the fluviatile barbel in the station of La Chapelette (Bouches-du-Rhône). However, Batbus meridionnalis is the most commonly parasitized host species in Spain. The study of parasites in freshwater fish of the genus Barbus in the Mediterranean region has shown a lot of variation, but most research has only focused on certain types of parasites. This limits our understanding of the full range of parasites that infect these fish. [ABSTRACT FROM AUTHOR]

In order to study the individual biology of endemic fish in China, lay a foundation for the conservation of its germplasm resources, and consolidate the basic biological data of endemic fish in the world. According to the ethical code and fishing permit, 21 samples of Schizothorax (Racoma) biddulphi (Günther, 1876) were collected from the Muzati River in Tarim River system from 2021 to 2022, and their morphological characteristics, age identification and anatomical observation were analyzed by classical biological methods. S. biddulphi has a long body, a conical head, a pointed snout and a lower mouth. Requires 2 pairs. The scales are small and neatly arranged; Bare or scaly chest; The lateral line scale is slightly larger. The lateral line is complete. The correlation equation between body length and body weight is: W = 4.148 × 10-5L2.791. There were 5 kinds of age identification materials: 15+ for lapillus and asteriscus, 14+ for vertebra, 11+ for opercular bone, and 9+ for anal scale. The peritoneal wall of S. biddulphi is black; The tooth type is 2·3·5-5·3·2; The gill harrow was 11~13 for laymen and 15~18 for experts. Diphysocyte; Gallbladder oval; The number of vertebrae is 4+42-43+1, and the number of ribs is 23 or 24. S. biddulphi is a special species in the Tarim River system, and its evolutionary adaptation is closely related to the uplift of the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

Most cyprinid fish breed from spring to summer. On the other hand, the timing of initiation and duration of gametogenesis in preparation for reproduction vary widely depending on the species. It is unclear what factors determine the types of timing and duration of gametogenesis. In order to infer the factors, it is necessary to clarify the gametogenesis process of as many species as possible, categorize them, and explore commonalities and differences between species belonging to different types of gametogenesis. In the present study, we determined the maturity of Hemigrammocypris neglecta, a temporary water-spawning fish of the subfamily Oxygastrinae, based on histological observations of the gonads. Female vitellogenesis began in May and continued during the breeding season from May to August. This species was a multiple-spawner that repeatedly ovulates and spawns multiple times during the breeding season. Male spermatogenesis (meiosis) began in April, and a large number of spermatozoa were observed in the testes and sperm duct from May to August, indicating that reproduction is possible during this period. The timing of the initiation of gametogenesis in spring/summer-spawning cyprinid fishes has been roughly divided into three types: autumn type, winter/spring type, and breeding season type. The female H. neglecta was the breeding season type. There are few species that belong to this type, suggesting that the type may have evolved independently with reflect the reproductive ecology of each species. The male is the winter/spring type, a characteristic common to the subfamily Oxygastrinae. [ABSTRACT FROM AUTHOR]

Nepal holds a high ichthyofaunal diversity, nevertheless, the molecular study of Nepalese fish is still in its early stages. The first record of a cyprinid fish species the Garra kempi Hora, 1921 for Nepal was reported from eastern Nepal's Lohandra River. Both morphology and molecular data affirmed the existence of G. kempi in Nepal's aquatic system. This species was previously reported from China (Tibet) and northern India. The maximum likelihood phylogenetic analysis and pairwise genetic distance based on Kimura 2 parameters using cytochrome oxidase subunit 1 (COI) segment sequences (665 bp) also confirmed the identity of the species as G. kempi. The COI sequences of specimens from Nepal formed a monophyletic clade with the sequence of G. kempi from northeastern India and the two contained a pairwise genetic distance of 1.8% only. The new record of G. kempi from Nepal warrants a detailed ichthyofaunal survey for documenting the fish diversity in Nepal. [ABSTRACT FROM AUTHOR]

With 75 known species, the freshwater fish genus Sinocyclocheilus is the largest cavefish radiation in the world and shows multiple adaptations for cave‐dwelling (stygomorphic adaptations), which include a range of traits such as eye degeneration (normal‐eyed, micro‐eyed and eyeless), depigmentation of skin, and in some species, the presence of "horns". Their behavioural adaptations to subterranean environments, however, are poorly understood. Wall‐following (WF) behaviour, where an organism remains in close contact with the boundary demarcating its habitat when in the dark, is a peculiar behaviour observed in a wide range of animals and is enhanced in cave dwellers. Hence, we hypothesise that wall‐following is also present in Sinocyclocheilus, possibly enhanced in eyeless species compared to eye bearing (normal‐/micro‐eyed species). Using 13 species representative of Sinocyclocheilus radiation and eye morphs, we designed a series of assays, based on pre‐existing methods for Astyanax mexicanus behavioural experiments, to examine wall‐following behaviour under three conditions. Our results indicate that eyeless species exhibit significantly enhanced intensities of WF compared to normal‐eyed species, with micro‐eyed forms demonstrating intermediate intensities in the WF distance. Using a mtDNA based dated phylogeny (chronogram with four clades A–D), we traced the degree of WF of these forms to outline common patterns. We show that the intensity of WF behaviour is higher in the subterranean clades compared to clades dominated by normal‐eyed free‐living species. We also found that eyeless species are highly sensitive to vibrations, whereas normal‐eyed species are the least sensitive. Since WF behaviour is presented to some degree in all Sinocyclocheilus species, and given that these fishes evolved in the late Miocene, we identify this behaviour as being ancestral with WF enhancement related to cave occupation. Results from this diversification‐scale study of cavefish behaviour suggest that enhanced wall‐following behaviour may be a convergent trait across all stygomorphic lineages. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand the systematic relationships between certain fish genera with oromandibular discs in the Labeoninae. At the same time, this was an opportunity to clarify the taxonomic status of certain species in the genera Ageneiogarra, Garra, Placocheilus, and other taxa distributed in China. Morphological comparison and molecular analysis were used in the study. The results showed that the genera with oromandibular discs had no recent common ancestor and that their oromandibular discs were the result of convergent evolution in different evolutionary lineages. Due to the homogeneity of their habitats, these fish have evolved oromandibular discs with similar appearance and structure. Both morphological and molecular evidence suggests that (1) Placocheilus cryptonemus distributed in the Nu‐Jiang (the Upper Salween River Basin), Yunnan, China, represent a new genus, here described as Pseudoplacocheilus, and (2) Garra micropulvinus occurring in the Panlong‐He (the upper portion of the Lo River, a branch of the Red River Basin) from Wenshan, Yunnan, represents another new genus, here described as Supradiscus. [ABSTRACT FROM AUTHOR]

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris‐Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni‐microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal‐fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3–4 unbranched and 9½–10½ dorsal‐fin branched rays, 12–14 pectoral‐fin rays, 7–8 pelvic‐fin rays, 2–3 unbranched and 6½–7½ branched anal‐fin rays, and 37–40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura‐2‐Parameter model distance of 5.3%. [ABSTRACT FROM AUTHOR]

Dactylogyrus labei is a dactylogyrid monogenean parasite originally described by Musselius and Gusev (1976) from Labeo rohita (Hamilton, 1822) (Teleostei: Cyprinidae) in two alternative forms: a typical from Lucknow, north India and an atypical from Kalyani, east India. Fresh specimens of D. labei were collected from Mizoram in northeast India, and examined morphologically using high-resolution digital image processing and analysis. The recovered monogeneans most closely resembled the atypical form of D. labei, with only minor differences, indicating conspecificity. The atypical form of D. labei is distinguished from other species of the genus by the following combination of characters: the dorsal bar wing-shaped, with a fine membrane on the anterior margin and a fenestration in the middle; the ventral bar casing nail-shaped with two small antero-lateral processes (3-rayed); the male copulatory tube loosely S-shaped, slender, with an inflated initial part; the accessory piece proximally tubular, distally a complex of multi-layered sheath guiding the copulatory tube, and the vagina tubular, with one small loop and vaginal pore surrounded with a flap-like structure. This study expands the geographical distribution of D. labei while improving its morphological descriptions. [ABSTRACT FROM AUTHOR]

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout (Onchorhynchus mykiss), Atlantic salmon (Salmo salar), common carp (Cyprinus carpio), goldfish (Carassius auratus), Gibel carp (Carassius gibelio) and the model fish zebrafish (Danio rerio). Among the genes studied, the most applicable for aquaculture are mstnba, pomc, and acvr2, the knockout of which leads to enhanced muscle growth; runx2b, mutants of which do not form bones in myoseptae; lepr, whose lack of function makes fish fast-growing; fads2, Δ6abc/5Mt, and Δ6bcMt, affecting the composition of fatty acids in fish meat; dnd mettl3, and wnt4a, mutants of which are sterile; and disease-susceptibility genes prmt7, gab3, gcJAM-A, and cxcr3.2. Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use. [ABSTRACT FROM AUTHOR]

One of the commonest pesticides used in agriculture is the fungicide carbendazim, which can cause deleterious effects on the physiology and behaviour of acutely and chronically exposed animals. However, few studies have evaluated the effects of carbendazim on fish behaviour and our main objective was to evaluate behavioural changes on adult zebrafish (Danio rerio) exposed to this fungicide. We studied 177 fishes, divided into control groups (not exposed) and treatment groups, exposed to a concentration of 120 µg/L for 7, 14, 21 and 28. Behavioural data were collected using the scan sampling, with instantaneous recording every 30 s. We evaluated and compared fish behaviours and aquarium occupancy between treatments and controls using Generalized Linear Mixed Models. The results indicate that carbendazim initially elicited slow swimming and later fast swimming, decreased aggressiveness, and caused behavioural changes indicative of distress, like abnormal swimming and the gulping of air in water surface. In the wild, this behavioural change can result in an increased predation risk and consequent decrease or extinction of populations, revealing important ecological issues for animal communities living in polluted water bodies. [ABSTRACT FROM AUTHOR]

The Northeast India has several natural water resources that support a variety of aquatic fauna. However, many parts of the region have remained unexplored for ichthyofauna. Research on the diversity of fishes in large water bodies has received significant attention from many researchers in the region. In contrast, studies on small stream rivers are very scant. Therefore, the present study aims to record the diversity of fish fauna in the small stream Diring River of Baksa District, Assam. In this survey, 27 species of fishes were recorded from five study sites. The dominant family was Cyprinidae, comprising 48% of the total fish species. The conservation status of the majority of species was Least Concern (88.8%) followed by Near Threatened (3.7%) and Vulnerable (3.7%). However, conservation status of 3.7% of the fish species was not evaluated by IUCN. The Shannon diversity index ranged from 1.5 to 2.6, the evenness index from 0.84 to 0.98, and the richness index from 1.1 to 2.6, indicating a good status of ichthyofaunal resources in the study sites. Since there were no existing records on the fish diversity of the Diring River, this maiden study might serve as baseline information for further research.

The morphological variation in Schizothorax oconnori, Schizothorax waltoni, and their natural hybrids was examined using conventional and image‐based analysis approaches. In total, 38 specimens of S. oconnori, 35 of S. waltoni, and 37 natural hybrids were collected from the Shigatse to the Lhasa section of the Yarlung Zangbo River during June and July 2021. A total of 21 morphometric, 4 meristic, and 27 truss variables were employed for the classification of S. oconnori, S. waltoni, and natural hybrids. Principal component analysis (PCA) and factor analysis (FA), as well as discriminant function analysis (DFA) and cluster analysis (CA), were conducted to identify differences based on traditional and truss measurements. Four principal components explained 75.92% of the variation among the morphometric characters, while five principal components accounted for 79.69% of the variation among the truss distances. FA results showed that factor 1 was associated with head shape, and factor 2 was associated with fins based on morphometric characters. Among the truss characters, factor 1 was related to head shape, and factor 2 was related to chest shape. In DFA, morphometric measurements achieved higher accuracy (100%) compared to truss distances (94.55%). The head morphology of hybrids exhibited intermediate traits between S. oconnori and S. waltoni. Both morphometry‐based and truss‐based clustering indicated that the morphology of natural hybrids leaned toward S. oconnori. In conclusion, the combination of morphometric and truss analysis is beneficial for classifying S. oconnori, S. waltoni, and their natural hybrids. The presence of natural hybrids could be considered an evolutionary response to the differentiation of nutritional and spatial niches in the middle Yarlung Zangbo River. [ABSTRACT FROM AUTHOR]

Garra rezai was recently described from two geographically distant areas in the Tigris drainage: upper Yanarsu River (eastern Türkiye) and Bouein-Sofla Creek (Iran). In the scope of this study, we aimed to ascertain the distribution ranges of G. rezai and its morphologically most similar congener G. rufa in Türkiye by examining 1165 specimens from 73 lots, which were collected between 1957 and 2023 and currently curated in two broad fish collections. To achieve this, we focused on two important diagnostic morphological characters which distinguish these two species: scales on predorsal mid-line between dorsal-fin origin and nape, and branched dorsal-fin rays. The results revealed that G. rufa is a widely distributed species in the Tigris-Euphrates catchment, while G. rezai is regionally widespread, with populations identified in at least six different regions within the Tigris catchment. Additionally, G. rezai is documented for the first time in the upper Euphrates. Furthermore, we identified the drainage areas where G. rezai co-exists with G. rufa. [ABSTRACT FROM AUTHOR]

Sinocyclocheilus guiyang, a new troglobitic species from a subterranean tributary of the upper Yangtze Basin in Guiyang City, Guizhou Province, China is described in the present study. The new species is distinguishable from its congeneric species by a combination of the following characters: tip of maxillary barbel reaching to posterior edge of orbit; forehead horn absent; eye absent (or highly reduced) and tip of pectoral fins not significantly extending beyond the base of the pelvic fin. Molecular evidence, based on the mitochondrial cytochrome b (cytb) gene, further supports the validity of the species and also reveals its close relationship with S. cyphotergous, S. multipunctatus, S. punctatus and S. sanxiaensis. In addition, the new species faces a high risk of extinction, underscoring the urgency for habitat protection measures within its limited range. [ABSTRACT FROM AUTHOR]

Geometric morphometrics is an efficient way to quantify biological shape variation and its covariation with other biotic or abiotic factors. The geometric information of an object is measured in a non-linear shape space after removing size, orientation, and position-related effects. This study was aimed to determine sexual dimorphism and morphological variation in body shape using landmark- based morphometrics by means of relative warp analysis. The indigenous freshwater fish Puntius sophore (Hamilton, 1822) (Cyprinidae) was selected as the model organism for the study. Adult male and female individuals were collected during July--August 2019 (breeding season) and March--April 2019 (non-breeding season) from the ponds of Bolpur, West Bengal, India. Prior to analysis, the images were digitised using the appropriate fourteen landmarks and relative wrap analysis was performed using appropriate soft ware. The results were then analysed, and the maximum relative displacements of adjacent landmarks were interpreted using canonical variate analysis (CVA) and principal component analysis (PCA). Significant body shape differences were found to be present in the non-breeding season and breeding season (male and female) populations of the species. Thus, geometric morphometrics can be used to understand the sexual dimorphism in natural populations of small fish species. [ABSTRACT FROM AUTHOR]

Olfaction is the major sense of smell in teleost involved in many physiological response and habitat acclimatization including food searching, migration for spawning, predator avoidance, reproduction behavior, as well as identification of fish of the same species. Our study illustrates the ultrastructure of the olfactory rosette of the grass carp Ctenopharyngodon idella (Cuvier and Valenciennes, 1844) by using Scanning Electron Microscope (SEM) and transmission Electron Microscope (TEM). Herein, the peripheral olfactory organs are represented by two olfactory rosettes lying in two nasal chambers, one on each side of fish snout. Each nasal chambers opens to the exterior by two nostrils a narrow inlet and wider outlet, segregated by a somewhat elevated, nasal bridge. The two nostrils are somewhat faraway as far as length of rosette's length to permit entering and leave water flow bearing odorant molecules to the nasal cavities. The SEM revealed that each olfactory rosette is elongated oval-shaped and made up of 48-50 foliar lamellae transversely arranged on both sides of a narrow median raphe. Alongside, the magnitude of lamellae differs in relation to their location on the raphe, since the larger are in the middle whereas their dimensions gradually reduced towards both ends of the rosette indicating that the number and magnitude of lamellae increase as the fish grow. Moreover, the lamellar surface comprises sensory and non-sensory areas concealed in a mucous layer and not distributed uniformly within the epithelial surface of the olfactory lamellae. Accordingly, The TEM observations indicated that the sensory areas holds four main receptor neurons, two are major including ciliated and microvillous receptor cells bearing either cilia or microvilli, respectively emitted from a dendritic knob. Additionally, two other minor rod-tipped and crypt cells bearing a compound rod cilium, or few microvilli and occult cilia emitted also from dendritic knob were rarely observed. From the other side, the non-sensory area comprises cylindrical flat top surface; ciliated non-sensory cells with motile long kinocilium and nonciliated stratified epithelial cells with fingerprint-like microridges both are mainly of supporting in addition of and ovoid goblet mucous cells in-between and stem basal cells. Collectively, our study revealed the general organization and ultrastructure of an important economic teleost fish that affects feeding habitat and has an important influence on the fish food intake. [ABSTRACT FROM AUTHOR]

Background: Cyprinidae, the largest fish family, encompasses approximately 367 genera and 3006 species. While they exhibit remarkable adaptability to diverse aquatic environments, it is exceptionally rare to find them in seawater, with the Far Eastern daces being of few exceptions. Therefore, the Far Eastern daces serve as a valuable model for studying the genetic mechanisms underlying seawater adaptation in Cyprinidae. Results: Here, we sequenced the chromosome-level genomes of two Far Eastern daces (Pseudaspius brandtii and P. hakonensis), the two known cyprinid fishes found in seawater, and performed comparative genomic analyses to investigate their genetic mechanism of seawater adaptation. Demographic history reconstruction of the two species reveals that their population dynamics are correlated with the glacial-interglacial cycles and sea level changes. Genomic analyses identified Pseudaspius-specific genetic innovations related to seawater adaptation, including positively selected genes, rapidly evolving genes, and conserved non-coding elements (CNEs). Functional assays of Pseudaspius-specific variants of the prolactin (prl) gene showed enhanced cell adaptation to greater osmolarity. Functional assays of Pseudaspius specific CNEs near atg7 and usp45 genes suggest that they exhibit higher promoter activity and significantly induced at high osmolarity. Conclusions: Our results reveal the genome-wide evidence for the evolutionary adaptation of cyprinid fishes to seawater, offering valuable insights into the molecular mechanisms supporting the survival of migratory fish in marine environments. These findings are significant as they contribute to our understanding of how cyprinid fishes navigate and thrive in diverse aquatic habitats, providing useful implications for the conservation and management of marine ecosystems. [ABSTRACT FROM AUTHOR]

Nod-like receptor pyrin domain-containing protein 3 (NLRP3) is a crucial member of NLRs family, which plays an important role in host defense. However, knowledge about inflammation response of NLRP3 in fish was scarce. Herein, a novel NLRP3 homologue (designated as CaNLRP3-like) was identified in Qihe crucian carp Carassius auratus. Full-length cDNA of CaNLRP3-like was composed of 3898 bp, which contained a 3093-bp open reading frame encoding. Structural analysis revealed that CaNLRP3-like lacked the PYD domain at N-terminus. Multiple sequence alignment and phylogenetic analysis revealed that CaNLRP3-like showed the high identity with the fishes in Cyprinidae, distinct from the branch formed by the mammals. Spatial expression analysis revealed that CaNLRP3-like was expressed in all examined tissues, with the highest expression levels in gill. Immune challenge experiments revealed that the expression of CaNLRP3-like was significantly up-regulated in six tissues in cases of challenge with Aeromonas hydrophila, LPS, and polyI:C. The recombined protein of CaNLRP3-like with 3Flag-tag was observed obviously in the cytoplasm. Furthermore, knockdown of CaNLRP3-like reduced the mRNA level of IL-1β, and increased the bacterial loading in liver, spleen, and head kidney. Vice versa, overexpression of CaNLRP3-like increased the mRNA expression of IL-1β, and decreased the bacterial loading in three detected tissues. Taken together, CaNLRP3-like gene, as a NLRP3 homologue, was identified and characterized in C. auratus, and these results revealed its role in regulating IL-1β expression and restricting bacterial infection in vivo, which shed light on the potential of CaNLRP3-like as a therapeutic target upon bacterial infection in teleost fish. [ABSTRACT FROM AUTHOR]

Molecular data from samples encompassing 22 nominal species of Poropuntius indicate that the species-level diversity in the genus has been vastly overestimated, likely due to inadequate taxon and geographic sampling and reliance on morphological characters that vary intra-specifically. The latter includes discrete mouth morphologies related to alternate feeding strategies (ecomorphs) within populations. One new species is described, Poropuntius anlaoensis Hoàng, Phạm & Trần, sp. nov., and 17 synonyms of six valid species names of Poropuntius, P. krempfi, P. alloiopleurus, P. huangchuchieni, P. laoensis, P. kontumensis, and P. deauratus, are recognised. Additional taxonomic changes in this widespread and generally poorly known genus are likely as more molecular and morphological data become available. [ABSTRACT FROM AUTHOR]

Molecular identification, such as DNA barcoding, is a useful tool that is widely applied in distinguishing species. To identify the cyprinid Acrossocheilus jishouensis, which was previously known to be restricted to only its type locality, we conducted molecular identification of this species based on 23 samples in five localities. Molecular identification based on the mitochondrial COI gene sequence showed that the morphologically similar samples from the five populations were all A. jishouensis, as the mean genetic distances between populations were very small (0.1–1.6%); thus, the distribution of this species was substantially expanded. The whole mitochondrial genome of one sample was also assembled, which was 16,594 bp in length and consisted of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and one control region. All PCGs began with ATG except the COI gene, which started with GTG; seven PCGs used the complete stop codon TAA, while four terminated in T(AA) and two ended with TAG. The overall base composition reflected a higher proportion of A+T than G+C and a positive AT-skew and negative GC-skew pattern except for the opposite in ND6. Phylogenetic relationships inferred using BI and ML methods revealed that both Acrossocheilus and Onychostoma were nonmonophyletic, which indicated that the traditional diagnoses between these two genera need to be assessed further. The results of this study not only expanded the known distribution ranges of A. jishouensis, but also provided a valuable data resource for future molecular and evolutionary studies of Acrossocheilus and other cyprinids in Barbinae. [ABSTRACT FROM AUTHOR]

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Candidia barbata is a primary freshwater fish distributed in the western portion of Taiwan Island, but this species has also been found in southern and eastern Taiwan. Previous studies have documented that human-intervention populations of freshwater fishes exist not only in eastern Taiwan but also widely. To investigate the native population genetic diversity and structure and evaluate the sources of human-intervention populations of C. barbata, the sequences from the mitochondrial DNA cytochrome b gene and d-loop region were analyzed. These results indicated that (1) the native populations were distributed in northern, northwestern, western and southwestern Taiwan; (2) the human-intervention populations originated from multiple sources, including native populations and aquarium stocks; (3) most aquarium stocks originated from the northwestern and western populations; (4) the geological history of Taiwan Island shaped the native distribution range and population genetic structure; (5) the effective size of the populations declined greatly; and (6) the native populations could be assorted into three distinct management significant units (α − γ). Finally, the human-mediated dispersal of freshwater species in Taiwan was more severe than expected and should be evaluated and monitored carefully. [ABSTRACT FROM AUTHOR]

The taxonomy and geographical distributions of Osteobrama species have historically posed challenges to ichthyologists, leading to uncertainties regarding their native ranges. While traditional taxonomy has proven valuable in classification, the utility of an integrated approach is restricted for this particular group due to limitations in combining information from biogeography, morphology, and genetic data. This study addresses the taxonomic puzzle arising from the recent identification of Osteobrama tikarpadaensis in the Mahanadi and Godavari Rivers, casting doubt on the actual distribution and systematics of both O. tikarpadaensis and Osteobrama vigorsii. The research reveals distinctions among specimens resembling O. vigorsii from the Krishna and Godavari riverine systems. Notably, specimens identified as O. vigorsii from the Indian Museum exhibit two pairs of barbels, while those from the Godavari River in this study are identified as O. tikarpadaensis. Inter-species genetic divergence and maximum likelihood phylogeny provide clear delineation between O. vigorsii and O. tikarpadaensis. The study suggests that O. vigorsii may be limited to the Krishna River system in southern India, while O. tikarpadaensis could potentially extend from the Mahanadi River in central India to the Godavari River in southern India. Proposed revision to morphological features for both species, accompanied by revised taxonomic keys, aim to facilitate accurate differentiation among Osteobrama congeners. The data generated by this research provide a resource for future systematic investigations into cyprinids in India and surrounding regions. Further, the genetic diversity information obtained from various riverine systems for Osteobrama species will be instrumental in guiding aquaculture practices and formulating effective conservation action plans. [ABSTRACT FROM AUTHOR]

The bilateral asymmetry was analysed on 259 fish specimens comprising six Barbus species collected in June-August 2010 from rivers in western Anatolia. The goals of this study are: (1) to check for the levels of bilateral asymmetry amid the ten morphological features of the six Barbus species and (2) to compare the levels of this asymmetry among the ten localities in western Anatolia. The possibility of applied investigations using bilateral asymmetry and fishes as an indicator of the health of the freshwater systems was also conducted. Statistical analyses have shown that the ten morphological traits chosen for this study exhibit variable levels of bilateral asymmetry in the six Barbus species collected from the ten localities studied. The asymmetry value was highest for snout length and lowest for the prepectoral fin length observed in B. pergamonensis. An increasing tendency in asymmetry levels was exhibited for each of the ten morphological traits in the fish length groups selected for each Barbus species assessed. The result of the individuals being right-handed or left-handed has shown that specific morphological characteristics are either dextral or sinistral or showed no bilateral asymmetry in different Barbus species studied. [ABSTRACT FROM AUTHOR]

Simple Summary: As an endemic and vulnerable fish from the upper Yangtze River in China, Schizothorax kozlovi holds significant scientific and ecological importance, yet it has received little attention so far. In this paper, we reported the characterization of the mitochondrial genome of S. kozlovi, and further investigated the phylogenetic relationships of Schizothorax. The results showed that the mitochondrial genome of S. kozlovi had a total size of 16,585 bp, a circular arrangement, and contained 13 PCGs, 22 tRNAs, two rRNAs, and two non-coding regions. Moreover, the phylogenetic analyses demonstrated that Schizothorax could be classified into four clades, and S. kozlovi was closely related to Schizothorax chongi. The present study enriched the basic biological data for S. kozlovi and provided fundamental references for the conservation of S. kozlovi and Schizothorax. Schizothorax kozlovi is an endemic and vulnerable fish species found in the upper Yangtze River in China. Over the past few years, the population resources of S. kozlovi have been nearly completely depleted owing to multiple contributing threats. While the complete mitochondrial genomes serve as important molecular markers for phylogenetic and genetic studies, the mitochondrial genome of S. kozlovi has still received little attention. In this study, we analyzed the characterization of the mitochondrial genome of S. kozlovi and investigated the phylogenetic relationships of Schizothorax. The complete mitochondrial genome of S. kozlovi was 16,585 bp in length, which contained thirty-seven genes (thirteen protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), twenty-two transfer RNA genes (tRNAs)) and two non-coding regions for the origin of light strand (OL) and the control region (CR). There were nine overlapping regions and seventeen intergenic spacers regions in the mitochondrial genome. The genome also showed a bias towards A + T content (55.01%) and had a positive AT-skew (0.08) and a negative GC-skew (−0.20). All the PCGs employed the ATG or GTG as the start codon and TAA, TAG, or single T as the stop codon. Additionally, all of the tRNAs displayed a typical cloverleaf secondary structure, except trnS1 which lacked the D arm. The phylogenetic analysis, based on the maximum likelihood (ML) and Bayesian inference (BI) methods, revealed that the topologies of the phylogenetic tree divided the Schizothorax into four clades and did not support the classification of Schizothorax based on morphology. The phylogenetic status of S. kozlovi was closely related to that of S. chongi. The present study provides valuable genomic information for S. kozlovi and new insights in phylogenetic relationships of Schizothorax. These data could also offer fundamental references and guidelines for the management and conservation of S. kozlovi and other species of Schizothorax. [ABSTRACT FROM AUTHOR]

Crucian carp (Carassius auratus gibelio), an extensively cultivated freshwater fish, was one of the model species for the study of fish immunology. Polyclonal antibodies were advantageous molecular tools for studying teleost immune system. Specifically, polyclonal antibodies reacting with immunoglobulins (Ig) were used successfully in studies of the teleost fishes. In the present study, we produced polyclonal antibody against CH2 domains of crucian carp IgM, and measured the in vivo dynamics of IgM mRNA caused by CyHV-2 infection. The recombinant protein IgM with relative molecular weight about 53 KD was correctly expressed in prokaryotic cells. The specificity of the polyclonal antibody was evaluated by Western blotting and results revealed that the antibody not only specifically recognized crucian carp serum but also cross-reacted with grass carp serum. Quantitative RT-PCR analysis demonstrated the expression of IgM mRNA changed significantly after CyHV-2 infection. The expression of IgM in the kidney increased and reached a maximum at 6 h post-infection (hpi), while dropped to a low level at 5 days post-infection (dpi). In conclusion, the expression of IgM was significantly upregulated in the kidney of crucian carp infected with CyHV-2, indicating that IgM played a potential role in systemic immunity against viral infection. Polyclonal antibody against crucian carp IgM had certain clinical relevance, which might provide insight into the early stage of virus infection and prevention of the disease. [ABSTRACT FROM AUTHOR]

The lotic and lentic ecosystem of Pakistan is a rich source of biodiversity, notably including important fish species. Earlier genetic studies pertinent to the family Cyprinidae are limited to some extent, this study aimed to provide comprehensive insights into the species inhabiting these water bodies. We identified 36 specimens nine genera and nine species viz: Labeo rohita, Crossocheilus latius, Ptychobarbus conirostris, Cirrhinus mrigala, Ctenopharyngodon idella, Salmostoma bacaila, Systomus sarana, Cyprinus carpio, Schizopygopsis stoliczkai within the Cyprinidae family. Utilizing key taxonomic features and DNA barcode analysis, we delineated intrinsic genetic variability among these species. An Fst analysis, conducted via R studio script revealed a variability range of 0.03-0.44. Additionally, to provide robust species identification QR codes and barcodes for each species were generated using an online code generator. This scannable QR code technique was adopted for the first time for cyprinids. The genetic distances based on kimura 2-parameter (K2P) model indicated differences of 0.16% within species and 23.09% within family. Notably, this study documents the COI sequence for Ptychobarbus conirostris into the Genbank database, a first time inclusion. Based on the outcomes of this study we conclude that the innovative utilization of DNA barcoding and QR codes provides explicit insights into the genetic variability among Cyprinidae fishes, suggesting their efficiency in the identification and characterization of cryptic species within these vital aquatic systems. [ABSTRACT FROM AUTHOR]

A year-long research was conducted with a novel purpose for categorizing and documenting the existing fish diversity and abundance of Bamui beel in Jamalpur district located in Northeast part of Bangladesh, within a time frame from July 2022 to June 2023. A total of 46 fish species were identified that belonged to 18 taxonomical families and 8 orders. The most abundant family was Cyprinidae (25%). Among 46 species, 37% were commonly available (CA) and 11% were abundantly available (AA) in terms of biodiversity status. According to the global conservational status, around 74% were reported as least concerned (LC) whereas 4% were nearly threatened (NT). On the other hand, in consonance with the conservational status of Bangladesh 52% were least concerned (LC) and 11% were endangered (EN). Pielou’s evenness score in Bamui beel was the highest (0.247) in pre-monsoon and the lowest (0.213) in monsoon. Shannon-Weaver diversity index was ranged from 1.992 to 2.114, whereas Simpson’s dominance index value was a maximum of 0.883 in pre-monsoon and a minimum of 0.852 in monsoon. The yearly fish production of the beel was 7.023 metric tons during experimental year. Besides this, small indigenous species (SIS) of fish dominated with 63.34% of the beel's species makeup. Nevertheless, the abundance and diversity of fish species are diminishing daily in this beel. For preserving the fish diversity of Bamui beel calls for the implementation of effective fishery management practices, vigilant monitoring to prevent overfishing, and a strong emphasis on raising awareness among fishermen. [ABSTRACT FROM AUTHOR]

Unnatural changes in river flow patterns resulting from peak‐operating hydropower plants adversely impact freshwater ecosystems. In particular, the rapid dewatering of shoreline habitats during artificial flow down‐ramping puts early fish life stages at a high risk of becoming stranded if they fail to follow receding water levels in time. While extensive research has been conducted on the effects of hydropeaking on salmonid species, there is limited knowledge on the diverse cyprinid family, particularly on vulnerable early life stages. Hence, this study aims to compare the larval stranding of two cyprinid species, the common barbel (Barbus barbus L.) and common nase (Chondrostoma nasus L.), in response to bank dewatering. We conducted larvae experiments in near‐natural mesocosms, simulating single flow down‐ramping events with varying down‐ramping rates (0.3–1.8 cm·min−1) during the day and at night to quantify stranding rates, also including water temperature and fish development. Our results reveal distinct diurnal patterns for both species, with higher stranding rates during the night than during the day in all experimental scenarios. The data also show higher stranding rates at faster down‐ramping, with interaction effects between down‐ramping rates and time of day. The stranding rates between the two species are similar across most of the scenarios. Scenarios with colder water temperatures show that nase larvae tend to strand more frequently than with warmer temperatures. In conclusion, the study results contribute to the ongoing discourse on hydropeaking mitigation by providing new perspectives on flow‐reduction effects on early cyprinid life stages. Mitigation measures should prioritize the periods during early larval development and factor in prevailing water temperatures. Lowering down‐ramping rates, especially during nighttime, will help minimizing negative impacts on aquatic ecosystems, particularly when combining flow rules and habitat restoration measures. [ABSTRACT FROM AUTHOR]

Purpose: Ligulosis caused by Ligula intestinalis adversely affects the fisheries carried out in the lakes and ponds, causing economic losses in the fish industry. In this study, it was aimed to reveal the molecular characterization of L. intestinalis isolates obtained from woodfish (Acanthobrama marmid) in Keban Dam Lake in Elazig province of Turkey by using mt-CO1 gene sequences and to determine the genetic differences and haplotypes between the isolates. Methods: In the examination made in terms of L. intestinalis, the intestine of the fish was opened with the help of fine-tipped scissors, the contents were allowed to come out, and the parasites were taken into a petri dish containing phosphate buffered saline (PBS). Then, L. intestinalis plerocercoids were taken into 15 ml falcon tubes containing 70% ethanol and stored at − 20 °C until further analysis. From each isolate, total gDNA was extracted from the plerocercoids. A partial (480 bp) mt-CO1 gene was amplified by PCR and sequenced unidirectionally. The final size of the trimmed sequences was 392 bp for 43 sequences. Sequence and haplotype analyses were performed, followed by phylogenetic analyses. Results: All isolates were confirmed as L. intestinalis by BLAST analysis. In addition, 87 nucleotide mutation positions were determined among 43 CO1 gene sequences. As a result of the haplotype network performed for the mt-CO1 gene region of L. intestinalis isolates; arranged in a star-like configuration with the main haplotype (Hap05), separated from other haplotypes by 1–6 mutation steps, and 29 haplotypes were identified, covering 13.9% (6/43) of the total isolates. Also, 75 variable (polymorphic) sites were determined, 52 of which were parsimony informative sites. Conclusions: The molecular characterization of L. intestinalis in woodfish (A. marmid) was identified for the first time in Turkey. [ABSTRACT FROM AUTHOR]

Despite a large number of studies on freshwater fish fauna in Syrian aquatic habitats lack of data exists for many. This study was conducted in Al-Bireh Dam, located in Wadi Al-Oyoun region, Hama Governorate of Syria and recorded Telestes pleurobipunctatus (Stephanidis, 1939) (Cyprinidae) for the first time. In April 2023, thirteen individuals of the species were caught using local fishing methods. The species is characterised by the presence of a dark band on the sides of the body extending from the front of the snout to the end of the caudal fin, and an orange spot at the base of the pectoral fin. This research sheds light on the qualitative composition of the fish fauna in Al-Bireh Dam Lake, as the species T. pleurobipunctatus is recorded for the first time in Syrian freshwaters.

The article investigates the diversity of ichthyofaunal in Haranbari Dam in Maharashtra, India. The study identifies the presence of local fish species belonging to different families and genera including Labeo rohita, Catla catla, Cirrhinu smrigala, Ctenopharynngodon idella, Acanthocobitis mooreh and Channa murulius, as well as introduced fish species belonging to Cyprinidae, Siluridae and Percidae.

The Cyprinidae fish’s gills are considered the permanent habitat for Dactylogyrids spp., common monogenean ectoparasites. This study aims to investigate the impact of monthly aquatic ecological dynamics on the diversity of Dactylogyrus. Moreover, the prevalence and species richness were correlated as well. A total of 140 fishes, representing 12 species from the family Cyprinidae, were collected from the Lesser Zab River, located in the northeast of Altuon-Kopri town, Kurdistan Region, Iraq. The study was conducted from August 2022 to July 2023. The collected fishes included: Acanthobrama marmid (37), Alburnus mossulensis (9), Barbus (B.) sharpey (5), Capoeta (C.) damascina (7), C. umbla (3), Carasobarbus luteus (10), Carassus (C.) auratus (13), C. carassus (3), Chondrostoma regium (18), Cyprinion macrostomum (5), Cyprinus carpio (26) and Luciobarbus xanthopterus (4). They were inspected weekly for diversity variation and richness of Dactylogyridis with different aquatic parameters such as pH, temperature, total dissolved salts (TDS) and electrical conductivity (EC). The collected data revealed the presence of various Dactylogyridis species with different prevalence and species richness. Monthly variations revealed that the highest species richness occurslowermost the lowermostoccurred in March 2023, and the lowest was observed in September 2022. According to aquatic parameters, only water temperature shows a significant negative correlation according to the species richness (p