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espl1 (extra spindle pole bodies like 1), a cysteine endopeptidase, is a mitotic key player in chromosomal segregation and centriole duplication during mitosis and meiosis. Considering the espl1 gene has not been reported in aquatic organisms, we reported the isolation and expression of the espl1 gene from loach. In this study, the full-length cDNA of espl1 was cloned for the first time in loach. In loach, the full-length cDNA of espl1 consisted of 6948 bp, the open reading frame (ORF) is 6240 bp, and the espl1 gene encodes 2139 amino acids. Moreover, the deduced amino acid sequences of espl1 in loach shared the highest identity with those of Cyprinus carpio (78.39%) and Sinocyclocheilus anshuiensis (78.27%), and the sequence homology among the various separases is confined to the C-terminal region. Furthermore, tissue-specific checking results indicated that the espl1 gene of the loach gene was highly expressed in the ovary and testis, especially in stage IV oocytes and stage IV testis by Real-time quantitative PCR (qPCR). Then, whole-mount in situ hybridization analyses revealed the expression of espl1 in the early development of loach. We found that the positive signal of espl1 was observed in the notochord during the early embryo development of loach. Last but not least, when treated with luteinizing hormone-releasing hormone analog (LHRH-A2), the mRNA expression of espl1 was significantly increased in the testes and ovaries. These observations suggest that the espl1 gene had a distinct and important role in the gonads of Loach. This study will be of value for further studies into the function of the espl1 gene in fish. [ABSTRACT FROM AUTHOR]

In this study, a natural tetraploid loach (4n = 100) was crossed with a diploid loach (2n = 50) thus creating the different offspring hybrid combinations 4n♀×2n♂、2n♀×4n♂. Chromosome samples of hybrid triploid loach fin cell passed for 20 times were prepared via conventional cold drop method. The chromosome number and karyotype were determined via Giemsa staining; Banding analysis were conducted via Ag-NORs and CMA3/DA/DAPI staining. The results showed that the metaphase chromosome number of the fin cells of the hybrid triploid loach was 3n = 75,and the karyotype formula was 15m+6sm+54t, NF = 96;three silver staining signal points were observed in the chromosome metaphase of hybrid triploid loach fin cells, located at the end region of the first pair of central centromeric chromosomes (M1); there were three CMA3 signal points in the chromosome metaphase of hybrid triploid loach fin cells, which were located at the region of chromosomes (M1).The study showed that the chromosome composition of hybrid triploid loach fin cells remained unchanged after 20 times of cell culture passage, and the chromosome number, karyotype and band type were consistent with other somatic chromosomes of triploid loach. The results laid the foundation for the cytogenetics of hybrid triploid loach and provided a theoretical basis for cytogenetics of triploid loaches. [ABSTRACT FROM AUTHOR]

The Poyang Lake region is home to large‐blackspot loaches (LBL), small‐blackspot loaches (SBL), and non‐blackspot loaches (NBL), Misgurnus anguillicaudatus. To investigate the impact of tyrosinase on spot development, the complementary DNAs (cDNA) of tyrosinase in M. anguillicaudatus (designated as Matyr) were cloned using the rapid amplification of cDNA ends (RACE)‐PCR method. The full‐length cDNA for Matyr was 2020 bp, and the open‐reading frame comprised 1617 bp, encoding a predicted protein with 538 amino acids. Phylogenetic studies revealed that MaTyr was first grouped with Tyr of Triplophysa tibetana and Leptobotia taeniops, and then Tyr of other cyprinid fish. The quantitative reverse‐transcription‐PCR results show that Matyr was highly expressed in the muscle, caudal fin, and dorsal skin. The Matyr gene's messenger RNA expression pattern steadily increased from the fertilized ovum period to the somitogenesis period, and from the muscle effect stage to 6 days after fertilization, it considerably increased (p < 0.01). The Matyr hybridization signals with similar location could be found in all developmental stages of three kinds of loaches using whole‐mount in situ hybridization (WISH) technology and were the strongest during the organ development period and melanin formation period. Dot hybridization signals in LBLs rapidly spread to the back of the body beginning at the period when the eyes first formed melanin, and their dimensions were larger than those of NBLs during the same time period. The body color of loaches could change reversibly with black/white background adaptation. The α‐msh, mitfa, and tyr are mainly expressed in loaches adapted with a black background. Tyr gene could be involved in the development of blackspots and body color polymorphism, and contribute to organ development in the loach. [ABSTRACT FROM AUTHOR]

This study analyses behavioural adaptations in a recently discovered European cave fish. Navigation in standardized labyrinth conditions was compared between this cave fish, its epigean ancestor, the European stone loach, Barbatula barbatula , and hybrid specimens. Loach behaviour was tracked and recorded using an infrared camera. In open field tests, in both dark and light conditions, cave loaches showed reduced thigmotaxis compared to the other two groups. Hybrid loaches generally showed strong avoidance of the open field, whereas epigean loaches avoided the open field more in light than in dark conditions. Other tests were performed in darkness only. Cave loaches showed more consistent lateralization in turning behaviour during exploration of the Y-maze than the other two groups, indicating a search strategy optimized for nonvisual navigation. In all groups, complex maze learning was evident in the first half of the 15 trials, with a reduction in latency of departure from the starting chamber, and in both time and track length to reach the food chamber. However, cave loaches were far more successful in finding food than were epigean loaches and hybrid loaches. When the path to the food chamber was altered, epigean loaches generally responded by changing their route, whereas cave loaches tended to continue following a previously learned path and hybrid loaches exhibited intermediate behaviours. In conclusion, the enhanced ability of cave loaches to navigating labyrinths in the dark compared to their epigean ancestor suggests the evolution of behavioural traits that optimize survival in caves. • Cave loaches showed less open field avoidance in darkness than epigean loaches. • Cave loaches showed most consistent lateralization of exploration in Y-maze test. • Cave loaches achieved greatest foraging success in darkness in complex maze. • In darkness, epigean loaches were least able to learn a complex pattern to navigate. • Hybrids' behaviours in darkness were often not intermediate of cave × epigean fish. [ABSTRACT FROM AUTHOR]

The ecological characteristics of the eight-barbel loach Lefua tokaiensis Ito, Hosoya, and Miyazaki were elucidated. Ecological field research was conducted at two localities: the montane stream of Houraiji and the Arao River of the Toyo River system in the Tokai region of Japan. The two localities showed high population density of L. tokaiensis, consisting of young-to-aged individuals. Loaches were likely to reproduce and migrate both upstream and downstream throughout year. Their lifespan was over 10 years, and loaches of more than ten generations simultaneously lived together. Growth rates slowed down strikingly with increasing age. The montane stream of Houraiji was suitable for the population of L. tokaiensis. The results of this study contribute to the protection of this endangered species. [ABSTRACT FROM AUTHOR]

In this experiment, brewer's yeast was used to replace part of the fish meal in the feed to formulate a high-fat and low-protein feed for Taiwan loach. The effects of brewer's yeast on the growth performance, muscle quality, hepatopancreas and pancreas carnitine content, intestinal flora, immunity, and antioxidant ability of Taiwan loach were preliminarily investigated. In experiment 1, 600 Taiwan loaches were randomly divided into 4 groups, and 1% (group A), 4% (group B), 8% (group C), and 12% (group D) of brewer's yeast was substituted for an equal amount of fishmeal in the basal diets. The loaches in each group were fed for 60 d. In experiment 2, 60 Taiwan loaches were selected and randomly divided into a control group (Group E) and a test group (Group F). The loaches were fed the basal diet and the high-fat and low-protein diet supplemented with 8% fishmeal, replaced by brewer's yeast. The experiment lasted for 60 days, and the growth performance, hepatopancreas carnitine content, muscle quality, intestinal flora, plasma antioxidant, and immune capacity indices of loaches in each group were determined. The results were as follows: the weight gain rate and specific growth rate were significantly higher in group C than those in groups A, B, and D (P < 0.05); the intestinal length ratio, muscle hardness, hepatopancreatic carnitine content, plasma superoxide dismutase activity, catalase activity, total antioxidant capacity, and lysozyme activity were significantly greater in group F than those in group E (P < 0.05); the Lactobacillus and Bifidobacterium counts in Group F were considerably higher than those in Group E (P < 0.05), and the Salmonella counts in Group F was significantly lower than that in Group E (P < 0.05); the survival rate, weight gain rate, bait coefficient, muscle crude protein, crude fat, viscosity, elasticity, cohesion, chewability, and restorative capacity were not significantly different between Group F and Group E (P > 0.05). The above results showed that adding 8% brewer's yeast to feed Taiwan loach instead of fish meal could enhance its hepatopancreatic carnitine synthesis, optimize the intestinal flora, improve the body's immune and antioxidant ability, and have a certain promotional effect on the intestinal development and muscle quality improvement. [ABSTRACT FROM AUTHOR]

We found an additional Canestrini's organ in some males of Cobitis lutheri, C. derzhavini, and Misgurnus chipisaniensis, which normally have one lamina circularis on the first branched ray of the pectoral fin. We consider this as a manifestation of atavism. In the case of C. lutheri and C. derzhavini, this phenomenon mimics the state observed in the Bibarba lineage, and in the case of the pond loach, in the Bicanestrinia lineage. It is suggested that the primitive ancestral state for the entire Northern Clade of loaches should be considered to be the presence of two or even three laminae circularis in the pectoral fin of sexually mature males. In most lineages this state is lost, however, there probably was a phylogenetic reversion in the ancestor of the Bicanestrinia group through fixation of the atavistic state as a norm. [ABSTRACT FROM AUTHOR]

A specimen of weatherloach was caught in the Lanterne stream at Chevigney-sur-l'Ognon (Rhône catchment, Doubs department, eastern France) on the 22nd of July 2020. It was photographed and initially identified as European weatherloach Misgurnus fossilis before being released. Upon further examination of the photographs, looking at the adipose crests on the caudal peduncle, the coloration pattern and morphometric data of the head, the specimen was then correctly identified as a non-native large-scale loach Misgurnus dabryanus, thus being the first record of this species in France. Monitoring must be put in place to know if there is an established population and to follow its possible propagation. [ABSTRACT FROM AUTHOR]

A population of weatherloach has been detected in the Schadgraben stream at Geispolsheim, near Strasbourg (Rhine catchment, eastern France) in autumn 2021 and identified as the European weatherloach Misgurnus fossilis. Another sixty-three weatherloaches were caught in this location the 19 May 2022. The examination of morphological and molecular data on preserved specimens allows to identify this population as the dojo weatherloch Misgurnus anguillicaudatus, an invasive species. The length-weight relationship of this population highlights its good health and establishment. A review of the knowledges about this invasive species is also done. Monitoring must be put in place in order to follow its propagation, threatening native fishes like the endangered M. fossilis. [ABSTRACT FROM AUTHOR]

This study examined the impact of tea polyphenols (TPs) on the intestinal flora of loaches (Paramisgurnus dabryanus) under chronic ammonia nitrogen stress using high-throughput sequencing. Two groups of 600 loaches were studied over one month, and they were separated into a control group and tea polyphenol group. Alpha and beta diversity analyses showed diverse bacterial communities, with significant differences in the abundance and uniformity observed initially but not between sampling time points. Cluster analyses revealed distinct differences in microbial communities between groups. A predictive function analysis indicated enrichment in pathways related to amino acid and nucleotide biosynthesis. These findings offer initial insights into how tea polyphenols may affect intestinal microbial communities in loaches under ammonia nitrogen stress. [ABSTRACT FROM AUTHOR]

Loaches of the genus Lepidocephalichthys are ubiquitous in Peninsular India and the nearby continental-shelf island of Sri Lanka. Four valid species are reported from this region: L. thermalis, a species reported from across this region; L. jonklaasi, confined to rainforests in southern Sri Lanka; L. coromandelensis, from the Eastern Ghats and L. guntea, from the northern Western Ghats of the Indian peninsula. Here, based on collections from 25 locations in 13 river basins in Sri Lanka and 20 locations across India, including a dataset downloaded from GenBank, we present a molecular phylogeny constructed from the mitochondrial cytochrome b (cytb) and cytochrome c oxidase subunit 1 (cox1) sequences. We show that ancestral Lepidocephalichthys colonized Sri Lanka in the late Miocene. Multiple back-migrations to India, as well as colonizations from the mainland, took place in the Plio-Pleistocene. The persistence on the island of L. jonklaasi, an obligatory rainforest associate, suggests that perhumid refugia existed in Sri Lanka throughout this time. Lepidocephalichthys thermalis appears to have colonized the Sri Lankan highlands as recently as the Pleistocene. The data suggest that Lepidocephalichthys thermalis is a species complex in which multiple species remain to be investigated and described, both in India and Sri Lanka. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of the co-feeding (C) period on the growth and survival of larvae of the yo-yo loach Botia lohachata ornamental species during the weaning period from live food (LF) to inert food (IF). The breeders were subjected to induced spawning using crude pituitary homogenate. A total of 2,400 larvae were used with an average initial weight of 0.39 ± 0.09 mg and an average total length of 4.08 ± 0.21 mm, from a single breeding pair. The live food was newly hatched nauplii of Artemia franciscana, and the inert diet was a commercial ration with 55% crude protein and two particle sizes (142-350 µm and 350-500 µm). As the first food, all larvae received A. franciscana during the first six days, except for the fasting (NC) and inert food (IF) groups. The following co-feeding strategies were employed: C4 = 4 days of co-feeding, C8 = 8 days of co-feeding, C12 = 12 days of co-feeding, and LF = Artemia during the entire experimental period. The longest period with live food promoted better larval growth rates. The specific growth rate of larvae fed live food during the entire period (LF) was higher than that of the other groups, followed by the co-feeding strategies. There was no effect (P > 0.01) on larval survival in the LF, C12, C8, and C4 groups, which ranged from 41% to 53% after 30 days. Treatment R resulted in high mortality and low growth, suggesting that live food should be the first food source for B. lohachata larvae. [ABSTRACT FROM AUTHOR]

Phylogeographic congruence among co‐distributed taxa is regarded as an inherent inference to vicariance events. Nonetheless, incongruent patterns of contemporary lineage divergence among taxa indicated that species differ in their response to common past events. To investigate the role of past events, ecological traits and lineage diversification time in shaping the contemporary phylogeographic patterns, comparative analyses were conducted for Tibetan stone loaches in the Himalayas using three gene markers and two ecological traits (depth of caudal peduncle in their length and presence/absence of posterior chamber of the air bladder). By a thorough sampling in two flanks of the Himalayas, the authors detected that phylogenetic breaks were spatially discordant and divergences of populations were also temporally asynchronous in co‐distributed loaches. Estimated divergence time using fossil‐calibrated node dating indicated that the Tibetan stone loaches colonised into the south flank of the Himalayas until the Pleistocene. The demographic expansions were also disconcerted between populations in north and south flanks, or east and west Himalayas. Ongoing gene flows between populations in north and south sides implied that the Himalayas do not strictly impede dispersal of cold‐adapted species. The results highlight that the quaternary climatic oscillation, in conjunction with ecological traits and lineage diversification time, shaped contemporary phylogenetic patterns of stone loaches in the Himalayas and provide new insights into the biodiversity and composition of species in the Himalayas and surrounding region. [ABSTRACT FROM AUTHOR]

The large-scale loach Paramisgurnus dabryanus is a freshwater fish native to East Asia except for Japan. However, its presence has been observed in various locations of Japan, and sympatric occurrences with the dojo loach Misgurnus anguillicaudatus, a related species native to Japan, have also been reported. Artificially induced inter-specific hybrids between the two species were reported viable, and their fertility was suggested at least in females. To avoid genetic introgression in native Japanese dojo loaches, a method for precise identification of the two loach species is necessary. Species identification based on morphology has sometimes led to misidentification in the Japanese population, and inter-specific hybrids were difficult to identify due to their morphological similarities. We therefore developed a nuclear DNA marker named PdaDra from repetitive sequences isolated by genomic DNA digestion with the restriction enzyme DraI. This marker could discriminate large-scale loaches from dojo loaches, showing predominant smear-like electrophoretic patterns with ladder-like bands in the large-scale loach and no amplification in most dojo loaches. The combined use of other DNA markers previously developed for the dojo loach also makes it possible to successfully identify inter-specific hybrids. The PdaDra marker thus provides quick and accurate identification of the large-scale loach and its inter-specific hybrids. [ABSTRACT FROM AUTHOR]

Simple Summary: The complete mitochondrial genome has been widely used in phylogenetics-related studies, as it offers valuable insights into evolutionary relationships. In this study, we reported the complete mitogenome of the elongate loach (Leptobotia elongata) and conducted a detailed analysis of its characteristics which was employed to infer phylogenetic relationships. These findings reveal that both the gene arrangement and composition of mitochondrial genes in the elongate loach are comparable to those found in other bony fishes. Our study further demonstrated that the Cobitidae species under investigation could be grouped into two distinct clades, with elongate loach showing a sister relationship with L. microphthalma. Collectively, our research enhanced the understanding of the mitochondrial genome structure and contributed to the phylogenetic analysis of the elongate loach. The elongate loach is an endemic fish in China. Previous studies have provided some insights into the mitochondrial genome composition and the phylogenetic relationships of the elongate loach inferred using protein-coding genes (PCGs), yet detailed information about it remains limited. Therefore, in this study we sequenced the complete mitochondrial genome of the elongate loach and analyzed its structural characteristics. The PCGs and mitochondrial genome were used for selective stress analysis and genomic comparative analysis. The complete mitochondrial genome of the elongate loach, together with those of 35 Cyprinidae species, was used to infer the phylogenetic relationships of the Cobitidae family through maximum likelihood (ML) reconstruction. The results showed that the genome sequence has a full length of 16,591 bp, which includes 13 PCGs, 22 transfer RNA genes (tRNA), 2 ribosomal RNA genes (rRNA), and 2 non-coding regions (CR D-loop and light chain sub-chain replication origin OL). Overall, the elongate loach shared the same gene arrangement and composition of the mitochondrial genes with other teleost fishes. The Ka/Ks ratios of all mitochondrial PCGs were less than 1, indicating that all of the PCGs were evolving under purifying selection. Genome comparison analyses showed a significant sequence homology of species of Leptobotia. A significant identity between L. elongata and the other five Leptobotia species was observed in the visualization result, except for L. mantschurica, which lacked the tRNA-Arg gene and had a shorter tRNA-Asp gene. The phylogenetic tree revealed that the Cobitidae species examined here can be grouped into two clades, with the elongate loach forming a sister relationship with L. microphthalma. This study could provide additional inferences for a better understanding of the phylogenetic relationships among Cobitidae species. [ABSTRACT FROM AUTHOR]

Four loaches, namely, Lepidocephalichthys guntea (Hamilton, 1822), Lepidocephalichthys annandalei (Chaudhuri, 1912), Lepidocephalichthys thermalis (Valenciennes, 1846), and Lepidocephalichthys berdmorei (Blyth, 1860) from the Cobitidae family, were collected from the Surma River, Bangladesh. Of the total 376 speciminia, 193 males (51.32%) and 183 females (48.67%) in number; were collected with the support of local fishermen using a variety of nets at 15-day intervals from November 2022 to April 2023. The length-weight relationship (LWR) parameters were analyzed using the equation W = a L b . L. annandalei displayed a notable isometric growth pattern, with a condition factor (K) ranging from 0.725 to 0.734. In addition, L. thermalis exhibited isometric growth among males, while females showcased positive allometric growth with a condition factor (K) varying between 0.697 and 0.714. L. guntea exhibited a consistent positive allometric growth pattern across all aspects, with a condition factor (K) ranging from 0.729 to 0.738. In contrast, L. berdmorei demonstrated positive allometric growth, but males and females both exhibited a negative allometric growth pattern. The condition factor (K) for L. berdmorei ranged from 0.699 to 0.702. This suggests a complex growth pattern influenced by both length and weight in every experimental loach. The research underscores the importance of recognizing gender-specific variations in growth patterns within species. [ABSTRACT FROM AUTHOR]

We used the Illumina MiSeq platform to sequence the complete mitochondrial genome of Triplophysa jianchuanensis (Cypriniformes: Cobitidae). The mitochondrial genome of T. jianchuanensis is 16,569 bp in length, and its genetic constitution and arrangement are consistent with those of the teleost taxon, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, an origin of light-strand replication, and a control region. The overall nucleotide base composition was 28.33% A, 27.25% T, 17.77% G, and 26.65% C. Phylogenetic analysis showed that T. jianchuanensis was grouped with T. venusta. These findings are valuable for further studies on the evolution, genetic diversity, and taxonomy of Triplophysa. [ABSTRACT FROM AUTHOR]

Mud loach (Misgurnus mizolepis) has long been consumed in Korea. Recently, Chinese mud loaches were replaced with expensive Korean mud loaches, owing to taste and preference. Such issues occur in aquatic food distribution processes, leading to inferior food delivery. Previously, a study was conducted to confirm the origin of mud loaches using genetic analysis. However, untargeted metabolites profiling of mud loaches has not been reported. Untargeted metabolomics provides information on the overall metabolic profiling of a sample, allowing the identification of new metabolites. Here, we analyzed the metabolites of mud loaches of different geographical origins using liquid chromatography (LC)-quadrupole-time-of-flight mass spectrometry (MS). Orthogonal partial least squares discriminant analysis from LC/MS datasets showed a clear distinction between Korean and Chinese mud loaches, and univariate statistical analysis showed significantly different metabolites between them. N-acetylhistidine and anserine were selected as biomarkers for geographical origin discrimination using the receiver operating characteristic curve. N-acetylhistidine and anserine levels were significantly higher in Chinese than in Korean mud loaches. These results indicate that metabolic analysis can be used to discriminate between the geographical origins of mud loaches, curtailing the inadvertent substitution of mud loaches from different regions. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the population genetics of Paramisgurnus dabryanus across six river basins in China. Two mitochondrial genes (Cytochrome b and control region) and 12 microsatellite markers were employed to analyze the population genetics of 370 and 994 individuals, respectively, collected from 37 geographic locations. The analyses of both mitochondrial and microsatellite DNA revealed high levels of genetic diversity in P. dabryanus populations across the six river basins. Interestingly, the northern populations (Songliao River, Haihe River, and Yellow River) showed lower levels of genetic diversity compared to the southern populations (Huaihe River, Yangtze River, and Pearl River). Furthermore, the genetic analysis based on mitochondrial genes revealed no clear boundary between populations from different river basins, indicating no bottlenecks of gene flow among populations. Microsatellite analysis, on the other hand, revealed significant genetic differentiation between northern and southern populations, suggesting the need of two management units for P. dabryanus. Demographic analysis indicated that the Yangtze River populations have probably experienced population bottlenecks in the past, but also experienced a population expansion during the Last Glacial Maximum (LGM) when the warm climate was suitable for Yangtze River dispersal and survival after a recent genetic bottleneck. The integration of mitochondrial and microsatellite DNA data suggested that the Yangtze River populations are the most suitable population as a donor for the other river basins of P. dabryanus. Our findings have important implications for the conservation and effective management strategies of P. dabryanus. [ABSTRACT FROM AUTHOR]

Herewith, the current status of the inland waters ichthyofauna of Türkiye is revised, and an updated checklist of the freshwater lampreys and fishes is presented. As of November 2023, the freshwater ichthyofauna of Türkiye is known to consist of 427 species belonging to 20 orders, 37 families, and 97 genera. Among these, 21 species (4.9%) are alien, and 215 species (50.4%) are considered endemic to Türkiye. The orders with the largest numbers of species in the ichthyofauna of Türkiye are the Cypriniformes (297 species, 69.6%), followed by the Cyprinodontiformes (26 species, 6.1%), the Salmoniformes (25 species, 5.9%), the Gobiiformes (20 species, 4.7%), the Siluriformes (13 species, 3.0%), and the Clupeiformes (9 species, 2.1%). At the family level, the Leuciscidae has the greatest number of species (126 species; 29.8% of the total species), followed by Nemacheilidae (63 species, 14.8%), Cyprinidae (59 species, 13.8%), Cobitidae (29 species, 6.8%), Salmonidae (25 species, 5.9%), Aphanidae (23 species, 5.4%), Gobiidae (20 species, 4.7%), and Gobionidae (15 species, 3.5%). According to IUCN Red List criteria, among 403 naturally distributed species (alien species not included), four fish species are extinct, and 99 species (24.4%) are classified as threatened extinctions, including 28 (6.9%) CR, 44 (10.8%) EN, and 27 (6.7%) VU. After the latest checklist published in 2020, a total of 56 species, including 26 newly identified species from Türkiye and 30 new records documented from Turkish inland waters, were added. By the way, a total of 17 species have been excluded, mostly because of synonymization. [ABSTRACT FROM AUTHOR]

In recent years, sex-controlled breeding has emerged as an effective strategy to enhance the yields of economic animals with different growth characteristics, while increasing the economic benefits of aquaculture. It is known that the NF-κB pathway participates in gonadal differentiation and reproduction. Therefore, we used the large-scale loach as a research model for the present study and selected an effective inhibitor of the NF-κB signaling pathway (QNZ). This, to investigates the impacts of the NF-κB signaling pathway on gonadal differentiation during a critical period of gonad development and after maturation. Simultaneously, the sex ratio bias and the reproductive capacities of adult fish were analyzed. Our results indicated that the inhibition of the NF-κB signaling pathway influenced the expression of genes related to gonad development, regulated the gene expression related to the brain-gonad-liver axis of juvenile loaches, and finally impacted the gonadal differentiation of the large-scale loach and promoted a male-biased sex ratio. Meanwhile, high QNZ concentrations affected the reproductive abilities of adult loaches and inhibited the growth performance of offspring. Thus, our results deepened the exploration of sex control in fish and provided a certain research basis for the sustainable development of the aquaculture industry. [Display omitted] • The inhibition of NF-κB pathway plays a role in the critical period of gonad differentiation and after gonad maturation. • The inhibition of NF-κB pathway results in the disorder of brain-gonad-liver axis in juvenile large-scale loaches. • The inhibition of NF-κB pathway leads to the male bias of sex ratio in Paramisgurnus dabryanus. [ABSTRACT FROM AUTHOR]

This paper is the second part of the "Ichthyofauna of the Fresh and Brackish Waters of Russia and Adjacent Areas: Annotated List with Taxonomic Comments", which we started in 2022 based on a critical analysis of scientific publications of the last 200 years, and on the data of the author's research. The current paper includes all currently known fishes of the order Cypriniformes of Russia and adjacent waters, represented by three suborders Catostomoidei, Cobitoidei and Cyprinoidei, comprising ten families, 64 genera and 177 species. The most specious families were the Leuciscidae (59 species/33.3% of all species), Gobionidae (35/19.8%) and Xenocyprididae (23/13.0%), which together represent just over 66% the total cypriniform species. Fourteen of the studied species (24.7% of all cyprinids in Russia) are introduced species, 21 species (11.9%) are endemic; 32 species (18.1%) are recorded from Russia for the first time. In relation to the habitat, 131 species live and breed exclusively in fresh waters, 31 species are of freshwater origin, but can also tolerate slightly brackish waters, ten species are represented by anadromous forms (all with residential populations), and three species are amphidromic, capable of live and reproduce both in brackish water and in freshwater. According to the IUCN criteria, the majority of fish are classified as Least Concern (135 species/76.3%), but two species, Cobitis taurica and Gobio tauricus, are Critically Endangered. [ABSTRACT FROM AUTHOR]

Nostril structures are important characteristics for generic diagnosis in Nemacheilidae and Cobitidae. Based on phylogenetic analysis, we found that 10 genera within Nemacheilidae (Eonemachilus, Guinemachilus, Lefua, Micronemacheilus, Oreonectes, Paranemachilus, Protonemacheilus, Traccatichthys, Troglonectes, and Yunnanilus) shared tube-shaped anterior nostrils and formed a monophyletic group. Morphologically, the location between the anterior and posterior nostrils was divided into three types: (i) separated, i.e., a distance greater than 1.5 times the diameter of the posterior nostril; (ii) adjacent, i.e., a distance shorter than the diameter of the posterior nostril; and (iii) closely set, i.e., posterior margin of the anterior nostril connected to the anterior margin of the posterior nostril. Thus, the 10 genera can be distinguished based on nostril features. Additionally, we describe one new genus, Guinemachilus gen. nov., and two new species, Guinemachilus pseudopulcherrimus sp. nov. and Paranemachilus chongzuo sp. nov. [ABSTRACT FROM AUTHOR]

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Risk analyses for invasive species often assume that the characteristics of future invaders will resemble those already successful, but these features may change.Here, we use data from more than 3,500 fish sampling events, sequencing of mitochondrial and nuclear genes and analyses of several traits describing non‐native fish to describe the irruption and rapid expansion of non‐native loaches in Catalonia, north‐east Iberian Peninsula, and framing this surge in the knowledge of previous invasions.We report the establishment of at least five (Cobitis bilineata, Misgurnus anguillicaudatus, Misgurnus bipartitus, Paramisgurnus dabryanus, and a yet undescribed Barbatula species) non‐native loach species in Catalonia, most of which are currently spreading. Furthermore, one of the two regionally native loach species (Cobitis paludica) has been introduced and is spreading through river basins where it is not native.Genetic analyses were fundamental to understand loach invasions, by clarifying specific statuses, identifying the origin of non‐native populations and/or detecting independent introduction events. Genetic results also highlighted the unresolved taxonomy of loaches, particularly for European Barbatula.Loaches are recent, diverse, and successful invaders whose traits differ from those of most previously established invasive fish species, signalling potential weaknesses of prevention of biological invasions based on prohibited species lists. We call for the development of more flexible management tools (e.g. based on fish traits and not only on species identities) and prioritising prevention and rapid responses to new introductions. [ABSTRACT FROM AUTHOR]

The Italian spined loach (Cobitis bilineata) is an elongated, small‐sized (<12 cm) spined loach native to northern Italy, Slovenia and Croatia. As for loaches in general, little is known about the individual movements of this loach in nature. Passive integrated transponders (PIT‐tags) are small (typically 7–32 mm), relatively cheap and allow tracking of individual fish movements and behaviour. A fundamental assumption in animal telemetry is that the performance of a tagged animal does not deviate substantially from its natural performance. Although PIT‐tagged fish often display high survival and tag retention, the effect varies between species and contexts, and few studies have looked at behavioural effects of PIT‐tagging. Here we demonstrate a PIT‐tagging methodology for spined loaches, and compare survival, activity and provoked escape response (maximum swimming speed) between tagged and control fish. We also track tag retention in the tagged fish. Italian spined loaches tagged with 12 mm PIT‐tags displayed high tag retention and no extra mortality, and no effects of tagging on activity or maximum swimming speed were observed. The tag‐to‐fish weight and length ratios in our study ranged from 2% to 5% and from 10% to 16%, respectively, and we conclude that PIT‐tagging, within these ratios, appears suitable for Italian spined loach. [ABSTRACT FROM AUTHOR]

The article focuses on how mountain formation and monsoon patterns influenced the diversification of Nemacheilid loaches in China's Hengduan Mountains. It mentions that Molecular analysis reveals how these factors shaped the evolutionary history and geographic distribution of these fish, with a focus on the Nemacheilini II lineage.

Loaches of the genus Sabanejewia are model organisms for many ichthyologic studies focusing on morphological and colour variation. The bright lateral spots—a part of the mimicry of this fish—cause a taxonomic puzzle. Common practice is that morphometric and molecular studies lack habitat assessments of species originating from different environments. In this study, we analysed body shape and colour variation within two species of Sabanejewia in order to reveal whether they are more affected by phylogeny or environmental conditions. The environmental parameters were obtained using satellite mapping tools, body shape using geometric morphometry, and the molecular identification of specimens using an analysis of mitochondrial DNA (sequence of the cytochrome b gene). Generalized linear mixed models were used for the analysis of lateral spot numbers, and principal components analysis to describe the changes in landmark position defined by the permutation tests. Results show a significant impact of the locality elevation and specimen's sex on the change of the body shape. We identified significant differences in the number of lateral spots, which are considered mimicry variation across an elevation gradient. Morphological differences of Sabanejewia spp. vary with ecological factors along the river continuum. [ABSTRACT FROM AUTHOR]

As a new freshwater aquaculture product, triploid loaches (Misgurnus anguillicaudatus) are characterized by fast growth, high-quality meat, high edibility, high resistance to disease, and sterility. In this study, a natural tetraploid loach (4n = 100) (♀) was crossed with a diploid loach (2n = 50) (♂), thus creating the hybrid triploid loach (3n = 75). The histological observations of triploid offspring and diploid controls at 4 days post-hatching (dph), 15dph, 22dph, and 50dph showed that most of the hybrid triploid loaches were abortive in the early gonad differentiation process. To explore its fertility mechanism, through transcriptome analyses of triploid offspring and diploid controls at four periods, 10 differentially expressed genes related to the early fertility mechanism were identified: amh, hormad1, rec8, h2b, plvap, zp3, h2a, nrb0b1, ddx4, and esr2. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs, two pathways were identified that are closely related to the early fertility mechanism at 50dph: the estrogen signaling pathway and steroid biosynthesis. The findings laid a foundation for further exploration of their molecular inhibition mechanism in hybrid triploid loaches. [ABSTRACT FROM AUTHOR]

This study aimed to explore the gill developmental mechanism of the high mortality rate of Paramisgurnus dabryanus larvae in the early life-history process. Based on histological observations with a optical microscope, we studied the ontogeny of the gill of P. dabryanus. The result indicated that external gills first appeared 12 h after hatching. The number of external branchial filaments greatly increased at 2 d after hatching (DAH). The internal branchial filament primordial was formed in the oropharyngeal cavity at 5 DAH. At 9 DAH, none of external branchial filaments were observed outside, but the fish operculum was completed covered. From 15 DAH forward, the filaments and lamellae of gills increased in number and length prominently, and the gills of the larvae were similar to those of juvenile fish. The specific activities of Na+/K+-ATPase steadily increased from 0 to 12 DAH and peaked at 15 DAH. After 15 DAH, the specific activities of Na+/K+-ATPase slightly decreased and then tended to remain steadily stable until the end of the experiment. There were abundant gill lamellae on the gill filaments at 40 DAH. The sensitive period of the development of larval and juvenile P. dabryanus was from 6 to 15 DAH. Our results provide information that may be useful for improving our understanding of the life history and ecology of loaches. [ABSTRACT FROM AUTHOR]

A review of the six recognized species of Pseudohomaloptera is provided. Counts in the original description of Pseudohomaloptera sexmaculata Fowler (1934) were incorrect and led to confusion in identifying populations of Pseudohomaloptera in mainland Southeast Asia, and the species is re‐described. The validity of Homaloptera septemmaculata Fowler (1934) is investigated and confirmed as a junior synonym of P. sexmaculata. P. sexmaculata and Pseudohomaloptera leonardi, similar morphologically and often misidentified, are widely distributed in mainland Southeast Asia, with P. sexmaculata in the Chao Phraya, Mae Klong and Pran Buri River basins, and P. leonardi in the Malay Peninsula and the Chao Phraya and Mekong River basins. Pseudohomaloptera yunnanensis and Pseudohomaloptera vulgaris have been reported from the Mekong basin of Thailand and Laos but appear to be restricted to Yunnan Province, China. A new species of Pseudohomaloptera is described from Sumatra. This is the southern‐most species and first record for the genus from the Indonesian island. An identification key is provided for all species of the genus. [ABSTRACT FROM AUTHOR]

For the period 2019-2021, three fish species of the family Cobitidae, caught from the upper section of the Danube River in Bulgaria, were subjected to ecologohelminthological investigation. Four specimens of Cobitis elongata Heckel & Kner, 1858 (two specimens from Kudelin biotope and two from Koshava biotope); six specimens of spined loach (Cobitis taenia Linnaeus, 1758) (from Koshava biotope) and one specimen of Sabanejewia bulgarica Drensky, 1928 (from Kudelin biotope) are objects of research. The trematode Asymphylodora tincae (Modeer, 1790) Lühe, 1909 was reported for the first time as a helminth of S. bulgarica. The nematode Pseudocapillaria tomentosa (Dujardin, 1845) Moravec, 1987 was reported for the first time as a helminth of C. elongat?. Kudelin and Koshava biotopes are new habitats for the found helminth species. During the helminthological examination of C. taenia, infection with helminths was not found. The study provides new data on helminth fauna and ecological indices (MI, MA, and P%) in the helminth communities of C. elongat? and S. bulgarica. [ABSTRACT FROM AUTHOR]

Wild fish populations are unceasingly diminishing in the rivers, ox‐bow lakes and floodplains in the Southwestern region of Bangladesh. Investigating the population status of vulnerable wild fish species are vital for the management and conservation of that species. This study aimed to identify the intra‐specific morphological variation and determine the population status of Lepidocephalichthys annandalei, in two rivers, the Nabaganga River in Jhenaidah (NRJ) and the Bhairab River in Jashore (BRJ) as well as a flood plain, the Dhakuria Beel in Jashore (DBJ) from Southwestern Bangladesh. Significant differences were observed in seven conventional and five truss‐based characters in univariate statistics. Conventional and truss‐network results from principal component analysis and CVA exhibited that populations were entirely intermixed, creating a compact cluster within intra‐population stages. Four principal components explained 51.93% of the variation in conventional morphometric characters and truss‐based characters. A UPGMA dendrogram was independently developed based on conventional and truss‐based morphometric characters. Among the individuals of NRJ and BRJ populations confirmed the presence of out‐group rather than the DBJ based on morphometric (conventional and truss) features. These notable isolations of populations of this species were supposed to be geographic disconnection and abiotic parameters. The evidence ensuing from the present study would be valuable for genetic studies as well as for in situ management. [ABSTRACT FROM AUTHOR]

In this study, the early development of Cobitis striata fuchigamii was described using aquarium-spawned eggs and juveniles. Egg yolk diameter after water absorption was 1.0‒1.1 mm, and the spherical, demersal eggs had a light-yellow yolk, no oil droplets, and low viscosity. Newly hatched larvae [4.0–4.5 mm in total length (TL)] had 44‒45 (27‒28 + 17‒18) myomeres (26‒27 between the pectoral fins and the middle of the anus), two pairs of short tubular outer gill filaments on the cheek, and only a few melanophores on parts of the eye. Notochord flexion began at 5.1–6.8 mm TL and ended at 10.0 mm TL. The number of fin rays on each fin was finalized at approximately 25.0 mm TL. Lateral line spots of the larvae were indistinct, and juveniles formed blotches at approximately 25.0 mm TL. The barbels were formed in the following order: third, second, and then first. The formation of membranous fins occurred in the following order: pectoral, caudal, dorsal, anal, and then pelvic; full fin ray complements occurred in the caudal, dorsal, anal, pectoral, and pelvic regions. Some individuals (5.1–7.5 mm TL at the flexion stage) had free lateral neuromasts on the caudal region, each with a short cupula. [ABSTRACT FROM AUTHOR]

There are 2 genetically divergent groups in the dojo loach Misgurnus anguillicaudatus: A and B. Although most wild-type diploids reproduce sexually, clonal diploids (clonal loach) reproduce gynogenetically in certain areas. Clonal loaches produce unreduced isogenic eggs by premeiotic endomitosis, and such diploid eggs develop gynogenetically following activation by the sperm of sympatric wild-type diploids. These clonal loaches have presumably arisen from past hybridization events between 2 different ancestors. The genomic differences between these 2 groups have not been completely elucidated. Thus, new genetic and cytogenetic markers are required to distinguish between these 2 groups. Here, we compared the 5S rDNA region to develop markers for the identification of different dojo loach groups. The nontranscribed sequence (NTS) of the 5S rDNA was highly polymorphic and group-specific. NTSs were found in clades of 2 different groups in clonal loaches. In contrast, we did not find any group-specific sequences in the coding region of the 5S rRNA gene. Sequences were located near the centromere of the short arm of the largest submetacentric chromosomes in groups A and B and clonal loaches. Thus, the 5S rDNA of the dojo loach is conserved at the chromosomal location. Whereas, the sequences of the NTS regions evolved group-specifically in the dojo loach, with the sequences of both groups being conserved in clonal loaches. [ABSTRACT FROM AUTHOR]

Nematode parasites of the family Anisakidae infect definitive hosts, such as fish‐eating birds and mammals, through primary intermediate hosts like copepods and secondary intermediate hosts like fishes. However, consumption of raw or undercooked fish can lead to nematode infection called anisakidosis in humans. We observed the presence of nematode infection in hillstream loaches of families Cobitidae and Nemacheilidae available for human consumption in the local markets in the northern parts of Western Ghats, India. Scanning electron micrograph and genetic identification employing mitochondrial cytochrome oxidase subunit II, identified the nematode to the genus Contracaecum. Histology of infected host revealed the presence of the parasite in muscles. Antioxidant enzyme analysis of host liver suggested that infection leads to oxidative stress in the fish. We suspect that a gradual increase in parasite infection of the loaches in the last decade could be attributed to various anthropogenic stressors that are altering riverine habitats. Since loaches are consumed by tribal people who often prepare the fish without degutting and possibly undercooked, there is a potential threat of human infection. [ABSTRACT FROM AUTHOR]

This paper reports the first account about dynamic changes on genetic diversity and population structure of Leptobotia microphthalma in the Yangtze River drainage due to dam constructions. The genetic diversity and population structure of twelve populations of L. microphthalma collected in 2010 and 2020 were estimated using 12 nuclear microsatellite markers. Reduction of genetic diversity between 2010 and 2020 was not significant in a paired t-test (p > 0.05), but population structure of L. microphthalma had a tendency to change: the genetic differentiation (Fst) among the five populations collected in 2010 were all insignificant (p > 0.05). However, differentiation (Fst) among some populations collected in 2020 were significant (p < 0.05), which indicated the population structure of L. microphthalma was changing. Correlation analysis indicated that negative correlations between the genetic diversities and geographical elevations among populations were significant for seven populations collected in 2020 (r = -0.819, p = 0.039), which means that populations of L. microphthalma in high elevation regions were more vulnerable than those in low elevation regions. Finally, some suggestions for conservation and restoration are proposed, such as artificial propagation, to prevent the further reduction of genetic diversity and population resources. [ABSTRACT FROM AUTHOR]

Sabanejewia romanica was recorded for the first time on the territory of Serbia in three direct tributaries of the Danube River (Rečka River, Slatinska River and Zamna River). This is the first record of the species outside Romania, the westernmost point of its occurrence and the first verified record of the species from the right tributaries of the Danube River. Genetic characterisation of the Serbian specimens showed that they are the most related to the Romanian S. romanica, with a high recorded net evolutionary divergence between them. Further studies with included populations from the whole geographical range of S. romanica should provide an accurate picture of genetic diversity and phylogenetic relations within the species. [ABSTRACT FROM AUTHOR]

Genetic differentiation in aquatic organisms is usually shaped by drainage connectivity. Sympatric aquatic species are thus expected to show similar population differentiation patterns and similar genetic responses to their habitats. Water bodies on the Qinghai--Tibet Plateau (QTP) have recently experienced dramatic physicochemical changes, threatening the biodiversity of aquatic organisms on the "roof of the world." To uncover ecological genetics in Tibetan loaches (Triplophysa)--the largest component of the QTP ichthyofauna--we characterized population differentiation patterns and adaptive mechanisms to salinity change in two sympatric and phylogenetically closely related Tibetan loaches, T. stewarti and T. stenura, by integrating population genomic, transcriptomic, and electron probe microanalysis approaches. Based on millions of genome-wide SNPs, the two Tibetan loach species show contrasting population differentiation patterns, with highly geographically structured and clear genetic differentiation among T. stewarti populations, whereas there is no such observation in T. stenura, which is also supported by otolith microchemistry mapping. While limited genetic signals of parallel adaption to salinity changes between the two species are found from either genetic or gene expression variation perspective, a catalog of genes involved in ion transport, energy metabolism, structural reorganization, immune response, detoxification, and signal transduction is identified to be related to adaptation to salinity change in Triplophysa loaches. Together, our findings broaden our understanding of the population characteristics and adaptive mechanisms in sympatric Tibetan loach species and would contribute to biodiversity conservation and management of aquatic organisms on the QTP. [ABSTRACT FROM AUTHOR]

The current status of the inland waters ichthyofauna of Iran is revised and updated. A total of 292 fish species belong to 3 classes, 24 orders, 36 families and 106 genera inhabit the inland waters of Iran. Among these, 29 species (9.9%) are exotic and 102 species (35%) are endemic. Orders with the largest numbers of species in the ichthyofauna of Iran are the Cypriniformes (182 species) followed by Gobiiformes (30 species), Cyprinodontiformes (15 species), Siluriformes (12 species), Clupeiformes (10 species), Acipenseriformes and Cichliformes (7 species) and Mugiliformes (6 species). At the family level, the Cyprinidae has the greatest number of species (74 species; 25.34% of the total species), followed by the Nemacheilidae (47 species), Leuciscidae (42 species), Gobiidae (30 species), Aphaniidae (11 species), Clupeidae (10 species), Acipenseridae and Cichlidae and Sisoridae (7 species in each) and Cobitidae and Mugilidae (6 species). [ABSTRACT FROM AUTHOR]

Summary: Iksookimia longicorpa and Cobitis hankugensis are two species of fish distributed only on the Korean Peninsula. They have a unique reproductive ecology that naturally hybridizes into three widely known unisexual types, maintaining populations of almost all females. In this study, the fine structure of the micropyles of I. longicorpa, C. hankugensis and their hybrids was analyzed to find out how egg–sperm interaction, a common interspecies isolation mechanism, is possible between heterogeneous species. Analysis of 30 eggs from five females of each species revealed that all had one funnel-shaped micropylar region and a manhole-shaped micropyle canal. With the exception of C. hankugensis, which had no spiral grooves or ridges, the rest had counterclockwise spiral grooves and ridges on the micropylar region. All five species, however, showed identical groove patterns for the micropyle canal. The egg size was the largest in HL (one from the C. hankugensis locus with one from the I. longicorpa locus) and the smallest in C. hankugensis. In the hybrids, the HL type had the largest egg and HHL (two from the C. hankugensis locus with one from the I. longicorpa locus) type the smallest. For the diameter of the micropylar region and micropyle canal, the diploid I. longicorpa, C. hankugensis and HL were smaller than those of the triploid. In addition, as the ratio of the canal diameter to the eggs was lower in I. longicorpa than in C. hankugensis, it was confirmed that I. longicorpa has a relatively small micropyle canal compared with C. hankugensis. [ABSTRACT FROM AUTHOR]

Spined loaches, Cobitis spp., have been studied in broad fields of research. Particularly, this taxon has attracted attention because of sexual interactions, such as reproductive interference and hybrid speciation, among species. Nevertheless, knowledge of the reproductive behaviors of this genus has been limited to findings from visual observations of aquarium-resident individuals. For this study, we shot videos and analyzed reproductive behaviors of Cobitis magnostriata in the field. We also investigated cues used by males to track females. Based on our observations conducted at a ditch near the shore of Lake Biwa during May–June, 2020, the sequence of courtship and spawning behaviors was divided into four phases: phase 1, a male tracks a female; phase 2, the male swims parallel to a female; phase 3, the male wraps the posterior part of the female's body from her dorsal fin and remains motionless; phase 4, after the male wraps the female tighter, the female vibrates to spawn. Additionally, we demonstrated that water vibrations initiate the male tracking behavior (phase 1). The adoption of such a non-species-specific cue might be one reason for which the sexual interspecific interactions have been widely reported in this genus. [ABSTRACT FROM AUTHOR]

Otolith growth and microstructural features of fish are essential to the understanding of the early fish lifecycle. This paper assesses the features of otoliths from laboratory-reared larval and juvenile Sinogastromyzon wui (S. wui, 0 to 25 days post-hatching) that were obtained as eggs from the Shilong Reach of Xijiang River between April and August 2021. We observed the development of the three pairs of otoliths (lapilli, sagittae, and asterisci) and compared the shape changes and growth of the lapilli and sagittae, as well as the timing and deposition rate of increments of the lapilli. The lapilli and the sagittae were visible on hatching, whereas the asterisci were present at four days post-hatching (dph). The shape of the sagitta changed more obviously than that of the lapillus, and a strong correlation was observed between sagitta shape changes and fish ontogenesis. The otolith shape greatly modulated during the post-flexion larval stage (Post-FLS), it corresponded with the formation period of individual fins. Analysis of the microstructural features indicated that lapilli were the optimal otolith for age determination and increment deposition rate confirmation. Using regression analysis of the known age and the number of lapillus daily increments, we demonstrated that the lapillus developmental increments were deposited daily, and the first increment formed at two days post-hatching. Our conclusions support employing the lapillus increment deposition rate and the time of the first daily increments in the determination of the age of wild larval and juvenile S. wui. [ABSTRACT FROM AUTHOR]

An expansion of a species range may happen unnoticed when an expanding species is similar in appearance to local species and distinguishable mainly by genetic methods. The morphological similarity of polyploid spined loaches of the hybrid complex Cobitis elongatoides–taenia–tanaitica with their diploid relatives makes their recent expansion in the rivers of Eastern Europe truly cryptic. We confirm this expansion and describe it in space and time by analyzing 20 museum collections from 1928 to 1985 and 92 recent sampling points from the Danube, Dniester, Southern Bug, Dnieper, Donets, and coastal rivers of the Sea of Azov. According to the museum collections, the numerical increase of polyploids relative to diploids occurred in the 1960–1980s that coincides with the time of intensive hydraulic construction when a series of reservoirs were created in the Middle Dnieper basin. Our sampling during 2000–2020 suggests that the trend toward the numerical increase of polyploids also continues in the twenty-first century. This expansion could have occurred under new ecological conditions, both due to the few clonal individuals that spread into the rivers of Eastern Europe as a result of postglacial recolonization, and due to invasions of polyploids from the Danube, Vistula, and Oder basins in the middle of the twentieth century. The expansion of polyploids is probably a consequence of their relatively high fitness in comparison with diploids in conditions of significant anthropogenization of river systems. [ABSTRACT FROM AUTHOR]

We studied the population genetic structure of Cobitis vettonica, an endangered freshwater fish species endemic to the Iberian Peninsula, in order to propose a biogeographic model of the responses of species to the multiple changes that occurred in the Iberian hydrological system during the Quaternary period. We also deciphered the relationship of C. vettonica with its sister species C. paludica, particularly in sympatric areas, and provide genetic information for conservation purposes. To achieve this goal, we analyzed both mitochondrial and nuclear data (the cytochrome b and the nuclear recombination activating 1 genes) and a battery of single‐nucleotide polymorphisms (SNPs) of 248 individuals of C. vettonica or C. paludica from 38 localities, including some sympatric ones, covering the entire distribution area of C. vettonica. We highlight the important role played by the hydrogeomorphological processes and climatic changes that occurred in the Iberian Peninsula during the Quaternary on both the population structure of C. vettonica and its relationship with its sister species C. paludica. Our results support the genetic introgression of populations at the eastern limit of the distribution of C. vettonica. Furthermore, we postulate genetic introgression in sympatric areas. Finally, we propose the establishment or expansion of four Operational Conservation Units (OCUs) for C. vettonica, and highlight the threat faced by its populations due to the low level of genetic diversity detected for some of its populations and genetic introgression with C. paludica, which could eventually displace C. vettonica, resulting in a loss of diversity in this species. [ABSTRACT FROM AUTHOR]

Pigment cell composition, pigment content, tyrosinase content and activity analysis were investigated on three kinds of loaches Misgurnus anguillicaudatus: big blackspot loaches (BBL), small blackspot loaches (SBL) and non-blackspot loaches (NBL), from Poyang Lake. Results showed that there were three types of skin pigment cells, namely melanophores, xanthophores and iridophores. Melanophores in dorsum were more than those in abdomen. Melanophore cytosomes in BBL were larger than those in SBL and NBL, and melanosomes were the largest in stage four. The melanophores in dorsal skin of SBL or NBL were small cell bodies, spindle-like and in chain distribution. There was an extremely significant difference in melanin content in BBL between the dorsum and abdomen (P < 0.01). There were no significant differences in melanin abdominal content, lutein and carotenoid contents among three kinds of loaches (P > 0.05). In dorsal skin, tyrosinase content was the highest in BBL, and it was significantly lower in NBL than in BBL and SBL (P < 0.01). This study reveals the differences in pigment and tyrosinase content in three kinds of loaches and provides a theoretical basis for further study of the mechanism of black spot formation. [ABSTRACT FROM AUTHOR]

The intestinal microbiota play a vital role in the growth and health of the host. Probiotics could influence the homeostasis of intestinal microbiota, but the relationship between species and ecosystem stability is poorly understood. Here, four diets with different doses of Bacillus cereus (control, 0 cfu/kg; BL7, 107 cfu/kg; BL9, 109 cfu/kg; and BL11, 1011 cfu/kg) were designed to investigate the intestinal microbiota in Paramisgurnus dabryanus. The growth experiment demonstrated that the growth performance and the indices of Chao1, phylogenetic diversity, Simpson and Shannon improved significantly after loaches were fed a BL11 diet. The dominant composition of intestinal microbiota at phylum, class and genus levels did not change in loach after feeding different diets. Categories of bacterial taxa revealed that rare taxa and conditionally rare taxa were the dominant bacterial taxa in intestinal microbiota of loach. B. cereus supplemented with 1011 cfu/kg promoted the stability of the ecological network of intestinal microbiota by reinforcing the cooperation of interspecific interactions, promoting operational taxonomic units to shape larger submodules and increasing module hubs species and connectors species. Results of functional prediction revealed that a total of 5692 functions were shared among the four groups, which accounted for 91.7% of overall functions. To sum up, dietary supplementation with B. cereus had no significant influences on the composition and bacterial taxa of intestinal microbiota and the composition of bacterial functions. A dose of B. cereus appropriate to the diet could improve the growth performance and promote the homeostasis of intestinal microbiota in loach. [ABSTRACT FROM AUTHOR]

Sabanejewia is a member of the family Cobitidae found in Europe and Asia. In previous studies, S. balcanica, S. caucasica, S. aurata and S. caspia were reported from Turkey. Of these S. aurata and S. caspia were reported from the Kura-Aras Basin. We examined morphological characters and molecular data of the Sabanejewia specimens from Turkish parts of the Kura-Aras river system to determine their taxonomic status. We found no differences between the Kura and Aras rivers' populations in terms of morphology, but different populations showed a genetic distance of 0.1-1.9%. All the studied populations were identified as S. aurata. In addition, we could not find any evidence for the presence of S. caucasica and S. caspia in Turkey. [ABSTRACT FROM AUTHOR]