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Local adaptation and phenotypic plasticity can lead to environment-related morphological and genetic variations in freshwater fish. Studying the responses of fish to environmental changes is crucial to understand their vulnerability to human-induced changes. Here, we used a latitudinal gradient as a proxy for past and present environmental factors and tested its influences on both genetic and morphological patterns. We selected as a suitable biogeographic model, the barbels, which inhabit 17 Adriatic basins of the central-southern Italian Peninsula, and explored association among attributes from genetic, morphological, and environmental analyses. The analysis of the mitochondrial DNA control region evidenced a southward significant increase in the number of private haplotypes, supporting the isolation of the southernmost populations related to the Mio-Pleistocene events. In contrast, morphology was mainly affected by changes in the present environmental conditions. Particularly, the number of scales and fish coloration were clearly associated to latitude, and thus thermal and hydrological conditions. Other morphometric and functional traits varied under the selective pressure of other environmental factors like elevation and distance from headwater. These results highlight the sensitivity of barbels to climate changes, which can serve as a basis for future eco-evolutionary and conservation studies. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of the high-altitude aquatic environment on indigenous fish metabolites, metabolomics studies were applied in this study. Widespread throughout the main stem of the Nujiang River of Schizothorax nukiangensis, we established sampling sites at high (3890 m) and low (2100 m) altitudes and selected six S. nukiangensis at each location, each weighing approximately 150 g and looking healthy. Then, metabolomics analysis was performed to compare the various metabolites of the two groups. Low concentrations of amino acids, dipeptides, eicosapentaenoic acid, docosahexaenoic acid, pentadecanoic acid, Thioetheramide-PC, 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine, 1-Stearoyl-sn-glycerol-3-phosphocholine, 1-Myristoyl-sn-glycero-3-phosphocholine and 1-Palmitoyl-sn-glycero-3-phosphocholine, high concentrations in S-Methyl-5'-thioadenosine, creatine, D-mannose-6-phosphate, D-mannose-1-phosphate, oleic acid and myristoleic acid were found in high-altitude fish liver. These differentially accumulated metabolites were involved in oxidative stress, energy metabolism, carbohydrate metabolism and lipid metabolism. mTOR signaling pathway, apoptosis and lysosome were the KEGG pathways that were enriched between different groups to ensure energy supply and limit tissue damage of fish at high altitudes. All these results contributed to the understanding of the high-altitude adaptation of S. nukiangensis in the Nujiang River. Nicotine and methoprene, two organic pollutants, performed differently in fish at different altitudes. Overall, our findings advanced the fundamental understanding of fish responses to high-altitude environments, adaptive mechanisms and organic contaminants pollution in the Nujiang River. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of endangered Enteromius thysi was determined from Cameroon in Western Africa. The genome was 16,688 bp in length, comprising 37 genes (13 PCGs, 2 rRNAs, 22 tRNAs, and an AT-rich control region). The heavy strand accommodates 28 genes (12 PCGs, 2 rRNAs, and 14 tRNAs), whereas the light strand holds 9 genes (NAD6 and 8 tRNAs). The E. thysi mitogenome is AT-biased (60.5%), as exhibited in other Enteromius species. Most of the PCGs start with the ATG initiation codon, except COI, with GTG, and seven PCGs end with the TAA termination codon, except some with an incomplete termination codon. Most of the tRNAs showed classical cloverleaf secondary structures, except tRNA-serine (trnS1). Bayesian phylogeny distinctly separated E. thysi from other congeners. The control regions of Enteromius species exhibited highly variable nucleotides, and parsimony-informative sites were found in the conserved sequence block-III (CSB-III) compared with other domains and a unique 9 bp tandem repeat (ATGCATGGT) in the variable-number tandem repeats (VNTRs) region of E. thysi. The present phylogeny with limited mitogenomes showed an uneven diversity and evolutionary patterns of Enteromius species distributed in the northwestern and southeastern riverine systems in Africa, which warrants further investigation. Based on the results of the present study, we recommend additional surveys, in-depth taxonomy, and the generation of more mitogenomes that could resolve the diversification pattern of Enteromius species in Africa. [ABSTRACT FROM AUTHOR]

The phylum Acanthocephala is an important group of parasites with more than 1,300 species parasitizing intestine of all major vertebrate groups. However, our present knowledge of the mitochondrial genomes of Acanthocephala remains very limited. In the present study, we sequenced and annotated the complete mitochondrial genome of Acanthogyrus (Acanthosentis) bilaspurensis (Gyracanthocephala: Quadrigyridae) for the first time based on the specimens recovered from the intestine of common carp Cyprinus carpio Linnaeus (Cyprinidae) in Pakistan. The mitochondrial genome of A. bilaspurensis is 13,360 bp in size and contains 36 genes, representing the smallest mitogenome of acanthocephalans reported so far. The mitogenome of A. bilaspurensis also has the lowest level of overall A+T contents (59.3%) in the mitogenomes of Eoacanthocephala, and the non-coding region 3 (NCR3) lies between trn S2 and trn I, which is different from all of the other acanthocephalan species. Phylogenetic analyses based on concatenating the amino acid sequences of 12 protein-coding genes using maximum likelihood (ML) and Bayesian inference (BI) methods revealed that the family Pseudoacanthocephalidae is a sister to the Arhythmacanthidae rather than the Cavisomatidae, and the families Rhadinorhynchidae and Cavisomatidae showed sister relationships. [ABSTRACT FROM AUTHOR]

The monitoring of ichthyofauna from rivers and rivulets crossing urban areas is important in the context of preserving ecosystems under continuous anthropic pressures. In addition, new invasive species may be observed. This study aims to present current data on the ichthyofauna of Becaș River, which has its entire course in Cluj-Napoca, Romania. For this purpose, alpha diversity, LWRs, Fulton condition factor (K) and relative condition factor (Kn) were determined. In total, 1216 specimens were analyzed, classified into 13 species, from 8 families. The species with the highest abundance was Pseudorasbora parva (46.46%), and the species with the lowest abundance were Cyprinus carpio and Perca fluviatilis (0.16%). Regarding LWRs, the lowest value of the b coefficient was obtained for Rutilus rutilus (2.7651) and the highest value for Phoxinus phoxinus (4.0868). The highest value of K was obtained for C. carpio (1.815) and the lowest value for Cobitis elongatoides (0.5942). The Kn was between 0.5436 (Gobio carpathicus) and 1.0330 (C. elongatoides). [ABSTRACT FROM AUTHOR]

Nematocera (lower Diptera) is a taxonomically diverse group with ~52 000 species in 40 families, including many important agricultural and sanitary pests. The number and composition of nematoceran infraorders have long been subject to debate. The use of mitochondrial genomes for resolving these questions shows considerable promise. Herein, we sequenced and annotated the complete or nearly complete mitochondrial genomes of eight nematoceran species from seven families, representing the first mitochondrial genomes of two infraorders and six families. They range in size from 14 447 to 16 255 bp and all contain 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes and an AT-rich region. Like other nematocerans, the arrangement of genes of their mitochondrial genomes is identical to the presumed ancestral arrangement. A phylogenetic analysis was conducted by using mitochondrial genomes of 116 representatives from Diptera, Mecoptera and Siphonaptera. Our phylogenetic results support both new and traditional arrangements. The small, highly specialized family Deuterophlebiidae appears to be sister to all remaining Diptera, while Nymphomyiidae and Blephariceridae are nested within Culicomorpha and Psychodomorpha, respectively; hence, the recognition of 'Blephariceromorpha' as a valid monophyletic infraorder is discouraged. Anisopodidae is supported as the sister group of Brachycera. [ABSTRACT FROM AUTHOR]

It is known that degassing processes are currently observed in the underwater part of the beach zone of Laspi Bay (the southern coast of Crimea). The site of gas emissions (methane) is confined to the coastal part of the bay and located at a distance of 15.0 - 40.0 m from the coastline. Data on the taxonomic richness and quantitative development of meiobenthos in Laspi Bay (2017) are presented for the first time in this study. The meiobenthic assemblages of the studied area were very diverse including representatives of 24 high taxa from Protozoa and Metazoa (phylum, class, order). The most numerous group at almost all stations was the free-living nematodes. The taxonomic richness by station did not reveal any noticeable variability, including 12 to 18 faunal groups, while an unevenness of spatial distribution in the density of meiobenthic settlements was clearly expressed. Minimum values of 63.2×10³-72.9×10³ ind./m² were noted in the seaward zone, and maximum values of 1368×10³-2051×10³ ind./m2 in the eastern coast where localized methane seepage areas were observed. [ABSTRACT FROM AUTHOR]

In this study, fish species diversity and protection criteria, habitat evaluation, and threat elements of the ichthyofauna of the Devrez Stream were examined monthly between April 2020 and March 2021. Eight fish taxa (7 natives, 1 non-native) belonging to four families (Cyprinidae, Gobionidae, Leuciscidae, Gobiidae) were identified. Chondrostoma angorense Elvira, 1987 (endemic) from the mentioned species was reported for the first time in the Devrez Stream. Squalius sp. (32.5%), Chondrostoma angorense (24.4%), Capoeta tinca (23.9%), and Alburnoides freyhofi (11.1%) were the most common and abundant species while Pseudorasbora parva (0.5%), Barbus anatolicus (1.2%), Alburnus goekhani (2.4%) and Neogobius fluviatilis (4%) were the most rarely encountered species in the stream. According to our observations, drought, agricultural irrigation, and Devrez Kızlaryolu Dam, which is under construction, were considered major threats to the fish fauna. [ABSTRACT FROM AUTHOR]

Copyright of Parasite (1252607X) is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mechanistic models are invaluable in ecological risk assessment (ERA) because they facilitate extrapolation of organism-level effects to population-level effects while accounting for species life history, ecology, and vulnerability. In this work, we developed a model framework to compare the potential effects of the fungicide chlorothalonil across four listed species of cyprinid fish and explore species-specific traits of importance at the population level. The model is an agent-based model based on the dynamic energy budget theory. Toxicokinetic-toxicodynamic sub-models were used for representing direct effects, whereas indirect effects were described by decreasing food availability. Exposure profiles were constructed based on hydroxychlorothalonil, given the relatively short half-life of parent chlorothalonil. Different exposure magnification factors were required to achieve a comparable population decrease across species. In particular, those species producing fewer eggs and with shorter lifespans appeared to be more vulnerable. Moreover, sequentially adding effect sub-models resulted in different outcomes depending on the interplay of life-history traits and density-dependent compensation effects. We conclude by stressing the importance of using models in ERA to account for species-specific characteristics and ecology, especially when dealing with listed species and in accordance with the necessity of reducing animal testing.

This study aimed to evaluate morphological differences between cultured and wild common carp, Cyprinus carpio L. Wild specimens were collected from fishers operating in the waters of the Shatt al-Arab River, Basrah, Iraq, while cultured specimens were obtained from the Aquaculture Unit of the Marine Science Centre, University of Basrah, Basrah, Iraq. Significant changes were detected in all eight morphometric and three meristic characters measured and counted. Boxplots by habitat and variable showed high divergence between the populations. The meristic counts were also higher in the cultured population, and, ultimately, the two populations diverged.

The purpose of the research is identifcation of epidemically and epizootically dangerous fsh species for opisthorchosis in the Novosibirsk Region.Materials and methods. Helminthological studies were carried out from 2002 to 2020. We studied a total of 2994 fsh specimens belonging to 8 species of Cyprinidae, carps and allies, namely, ide, Leuciscus idus (L.); dace, L. leuciscus (L.); bream, Abramis brama (L.); roach, Rutilus rutilus (L.); verkhovka, Leucaspius delineatus (Heckel); crucian carp, Carassius carassius (L.); gudgeon, Gobio gobio (L.); and minnow, Phoxinus phoxinus (L.). The fsh were identifed to species according to the fsh guide. To identify Opisthorchidae metacercariae in fsh muscles, the compressor method generally accepted in helminthology was used. The Opisthorchidae metacercariae were identifed using the freshwater fsh parasite guide.Results and discussion. Of 8 studied fsh species of the family Cyprinidae in the Novosibirsk region, the Opisthorchidae metacercariae infection was noted in 7 species (ide, dace, roach, bream, verkhovka, gudgeon, and crucian carp). The following Opisthorchidae species were recorded in the studied fsh: O. felineus, M. bilis, M. xanthosomus, and Metorchis spp. The O. felineus metacercariae were most often found in the supplementary host, in 12.9 % of cases, and M. bilis, M. xanthosomus and Metorchis spp. larvae were found much less often. In terms of epidemy, the ide and bream having large commercial sizes are the most dangerous: the ide as the most heavily infected species, and the bream as the most often caught and eaten by humans. Small non-commercial fsh (the dace, roach, verkhovka, as well as the small ide and bream) are of great epizootological importance, since they are used for food for domestic and wild animals most often. Infected fsh were only found at unregulated marketplaces; the infection prevalence in the roach was 35.5%, of which 22.6% were affected by O. felineus metacercariae, and 12.9% by M. xanthosomus metacercariae.

Bu çalışmada Özlüce Baraj Gölü’nde yaşayan Luciobarbus barbulus (Heckel 1847), Luciobarbus esocinus Heckel 1843 ve Luciobarbus xanthopterus Heckel 1843 türlerine ait 51 morfometrik ve 8 meristik karakter özellikleri incelenmiştir. Morfometrik karakterlerin ve birbirine oranlarının maksimum, minimum, ortalama, standart sapma, standart hata ve değişim katsayıları hesaplanmıştır. Ayrıca, morfometrik ölçümlerin standart boy oranlarına ait regresyon denklemi ile korelasyon katsayıları hesaplanmış olup bunun sonucunda pozitif yönde kuvvetli ilişkiler olduğu belirlenmiştir. Meristik karakterlerden, yanal çizgi ve transversal yöndeki pul sayıları, yüzgeçlerdeki basit ve yumuşak ışın sayıları, solungaç diken sayıları, farinks diş sıra ve sayıları ortaya konarak her türe ait tanımlayıcı özellikler belirlenmiştir.

Many economically important fish have a long sexual maturation cycle, with the first sexual maturation time exceeding four years, which poses a long-term challenge for the cultivation of excellent varieties of these fish. Gonadal development and reproductive timing of fish are closely related to changes in environmental temperature. This study used the common carp as an economic fish model and set up three aquaculture modes for a one-month old common carp population: constant temperature test group (CTTG), normal temperature control group (NTCG), and variable temperature control group (VTCG). A long-term (approximately 11 months), temperature-controlled aquaculture experiment was conducted. The results of growth traits and gonadal development tests showed that at 10 months, the body length and weight of the CTTG were significantly higher than those of the other two groups. At seven months, the gonadosomatic index (GSI) value of CTTG was also significantly higher than that of the other two groups; At 10 months, the serum estradiol (E2) concentration of CTTG was significantly higher than that of the other two groups, while the testosterone (T) levels of VTCG and CTTG were significantly higher than those of NTCG, and only the 11-ketotestosterone (11-KT) concentration of VTCG was significantly higher than that of the other two groups. Simultaneously, qPCR analysis of sex hormone regulatory genes revealed that the expression of Cyp19a1a in CTTG ovaries was significantly higher than that in NTCG and VTCG ovaries, whereas the expression of Cyp11b and Hsd11b2 in VTCG ovaries was significantly higher than that in NTCG and CTTG ovaries. At 12 months, artificial reproduction revealed that only fish from the CTTG (66.67%) successfully laid eggs and fertilized normally. The results indicate that long-term constant temperature cultivation at 28 °C starting from the juvenile stage is not only beneficial for the body growth of common carp, but also promotes their gonadal development. This may be due to the conversion of T into E2 by Cyp19a1a in the common carp, ultimately facilitating the functional development of gonadal tissue under hypothalamus-pituitary-gonadal (HPG) axis regulation, normal egg laying, and fertilization. This study reduced the normal first sexual maturation time of common carp by at least 50% and provides a reference for the rapid cultivation of excellent varieties of other economically important fishes. [Display omitted] • Common carp has a high yield and is an ideal model for the Cyprinidae family. • Constant temperature aquaculture promote the gonadal development of common carp. • This method reduced the sexual maturation time of common carp by at least 50%. • This method can be directly used for rapid cultivation of excellent varieties. [ABSTRACT FROM AUTHOR]

Garra ngopi sp. n., a new Labeoninae species, is described from the Tinam stream of the Tissa River (district Longding), which is a headwater of the Brahmaputra River basin in Arunachal Pradesh, North–Eastern India. The new species is distinguished from its congeners by the following combination of characters: smooth snout with 7–8 shallow pits forming a pseudo groove structure on anterior most of snout; 4–5 shallow pits on both sides of snout, 2 + 2 shallow pits on rostrum midst of snout; 11–13 shallow pits situated in between nares; dorsal, pectoral and pelvic fins spread with two to four smooth and shallow pits; caudal fin rays spread with numerous shallow pits are very distinct. Head without proboscis; 35–36 lateral line scales; 9–10 predorsal scales; absence of scales on chest and belly. Evidences of genetic analyses (genetic distance, phylogenetic clustering and species delimitation), on the basis of mitochondrial gene (cox1) indicated that the species was distinct from other known congeners. [ABSTRACT FROM AUTHOR]

This correction notice addresses the absence of ZooBank registration in the original article titled "New insights into the phylogeny of Carasobarbus Karaman, 1971 (Actinopterygii, Cyprinidae) with the description of three new species." The corrected version of the article now includes the necessary registration information in compliance with the International Code of Zoological Nomenclature. The authors of the original article are Arash Jouladeh-Roudbar, Cüneyt Kaya, Saber Vatandoust, and Hamid Reza Ghanavi. [Extracted from the article]

Six different temperate zone species of Cyprinidae family members, which are adapted to different harsh environmental conditions, were analyzed versus cold-acclimated Salmonid. Hemoglobin diversity in the studied species was investigated with a modified form of isoelectric pH: 3.5-10 ampholite system. 6 isohemoglobin bands were observed for cold-acclimated Oncorhynchus mykiss 8 isohemoglobin were observed for Chalcalburnus tarichi 9 for Cyprinion macrostomus and Sarkisla (Sivas) Cyprinus carpio, 11 Garra rufa and finally 12 for Todurge (Sivas) Cyprinus carpio. Cathodic/anodic ratios were found equal to 1for control and the fish adapted to available conditions. However, these ratios were found below 1 when environmental conditions were changed for fish, which are adapted to these poorly oxygenated conditions. Different environmentally adapted fish species are representing various isohemoglobins bands pattern. The species used as a control group in this study shown the lower isohemoglobin bands form. On the other hand, different forms of temperate climate Cyprinidae family member are produced isohemoglobins bands pattern, and the number of these band were higher than control group, depending on different adaptation conditions. The majority of these protein bands were anadic and it can be said that fish are producing anodic hemoglobin protein, when environmental conditions was changed to poorly oxygenated milieu.

The mesonephros ultrastructure has been studied for 12 specimens of sexually mature Carassius gibelio Bloch 1782 living in the freshwater Finogenov Pond and in the middle reaches of the Khara River (salinity of 6‰). Both reservoirs belong to the basin of the Volga River. A slight increase in the water salinity up to 6‰ primarily caused changes in the quantitative characteristics of leukocyte mitochondria and in all types of epithelial cells, as well as specialized types of inclusions in eosinophils, macrophages, proximal tubules type I, and distal tubules of the nephron. There were also changes in the nuclear structures of some types of interstitial cells and epitheliocytes. In the nephron tubules, epithelial cells of smaller sizes were registered, in the epithelial cells of the tubules, there was a more developed smooth endoplasmic reticulum, as well as a shorter brush border of the proximal tubule cells. As the water salinity increased, the area of the renal corpuscles, of glomerular capillaries, and of podocytes decreased, the thickness of the basement membrane and mass transfer in the renal corpuscles and tubules changed as well. Cytological rearrangements during the transition of the stenohaline freshwater species to brackish water testified to the high adaptive capacity of the cellular structures of the mesonephros. [ABSTRACT FROM AUTHOR]

Loop-mediated isothermal amplification (LAMP) is a rapid molecular detection technique that has been used as a diagnostic tool for detecting human and animal pathogens for over 20 years and is promising for detecting environmental DNA shed by invasive species. We designed a LAMP assay to detect the invasive carps, silver carp (Hypophthalmichthys molitrix), bighead carp (Hypophthalmichthys nobilis), black carp (Mylopharyngodon piceus), and grass carp (Ctenopharyngodon idella). To determine the sensitivity of the LAMP assay, we determined limit of detection (LOD) for each invasive carp species and compared with the performance of a grass carp quantitative PCR (qPCR) assay in LOD and in a mesocosm study. We used two grass carp densities, 3 juvenile grass carp in one mesocosm and 33 juvenile grass carp in the other. Prior to adding grass carp to the mesocosms, we added 68 kg of fathead minnows (Pimephales promelas) to each mesocosm to simulate farm ponds used for raising bait fish. We filtered 500 mL of water per sample to compare LAMP and qPCR analysis, and we collected 50 mL grab samples that were only analyzed using qPCR to gain additional data using a higher-throughput method to monitor environmental DNA (eDNA) levels throughout the study period. No eDNA for any of the four invasive carp species was detected in water collected from the mesocosms during the three days prior to adding grass carp. Forty-eight hours after grass carp addition to mesocosms, we detected grass carp eDNA in the mesocosm containing 33 grass carp using the LAMP assay. However, we failed to detect any grass carp DNA in the mesocosm containing 3 grass carp with the LAMP assay throughout the study. We analyzed the data using an occupancy model and found that the 500 mL filter samples yielded a higher eDNA capture probability than 50 mL grab samples in the mesocosm containing three grass carp but had similar eDNA capture probability in the mesocosm containing 33 grass carp. Both LAMP and qPCR reliably detected grass carp eDNA 2 days after grass carp addition, but detections were more consistent with qPCR. The LAMP assay may have utility for certain niche uses because it can be used to rapidly analyze eDNA samples and is robust to inhibition, despite having some limitations. [ABSTRACT FROM AUTHOR]

Two mitochondrial genes (cytochrome oxidase I and cytochrome b) were examined to compare an isolated population of the Italian minnow in the central Apennines to other populations in the species' range (Po plain) and other European minnow species. Both mitochondrial markers showed a new haplotype, fixed in a sample of 30 specimens, never observed in the main species distribution range, and ostensibly divergent from other Italian minnow haplotypes. The result suggests a long history of isolation, probably preceding the Holocene retreat northwards of the Po River. This relict population is now at serious extinction risk owing to habitat loss and predation by alien trout restocked into the wild for recreational fishing purposes. [ABSTRACT FROM AUTHOR]

Six populations of morphologically similar Enteromius specimens with a weakly thickened and serrated dorsal spine from the Lowa basin were investigated using an integrative approach including qualitative characters, multivariate morphometrics, and DNA analyses (mtCOI and ncMyh6). These populations are nested within the COI lineage of the E. miolepis species-complex, but differ from all known Enteromius species from the Congo basin, by their dorsal spine morphology, colour pattern, and scale pattern at the dorsal-fin base. In addition, they represent two distinct COI lineages (genetic distance: 5.6–6.1%), with four populations forming a single well-supported lineage described as a new species, Enteromius radari sp. nov. The two remaining populations are sister to the E. miolepis lineage from the Itimbiri. The incongruent position of these two populations in the COI tree may point to past introgressive hybridization events, incomplete lineage sorting, or recent speciation. Analysis of a ncDNA marker (Myh6) did not provide more information due to its slow mutation rate. These results are indicative for introgression or mtDNA capture and provide the first report for such an evolutionary event in Enteromius from the Congo basin. [ABSTRACT FROM AUTHOR]

In an attempt to disentangle the complex taxonomy of the Labeobarbus species of the Epulu River, a right bank headwater affluent of the Aruwimi, Central Congo basin, a morphological study was undertaken on 221 specimens from the Epulu and 32 type specimens. As a result, five different species have been distinguished, including four so-called rubberlips, L. caudovittatus, L. macroceps, L. mawambiensis, and L. sp. 'thick lip', and one chiselmouth, L. longidorsalis. While rubberlips have a curved mouth with well-developed lips and often a mental lobe, chiselmouths have a straight mouth with a keratinised cutting edge on the lower jaw. Among the specimens examined, several presented an intermediate mouth morphology between L. mawambiensis and L. longidorsalis, either with one or two pairs of barbels. One specimen exhibited an intermediate morphology between L. mawambiensis and L. macroceps. This morphological study, complemented with a molecular study of the mitochondrial gene cytochrome b (cyt b), suggests that these intermediates are probably hybrid specimens. The Epulu case is reminiscent to a case of possible hybridisation recently discovered in the Inkisi River (Lower Congo basin), but differs in having a lower relative abundance of hybrid specimens in the population, and in phylogenetic patterns. [ABSTRACT FROM AUTHOR]

The Length-weight relationships (LWRs) are very important to data for accurate estimate of populations in stock menagement. In this study, the length-weight relationships and Fulton's condition factor (K) of some fish in Göynük Stream, Murat River (Bingöl/Turkiye) were examined. The LWRs and condition factor (K) of Cyprinon macrostomus, Garra rufa, Barbus lacerta, and Acanthobrama marmid were analyzed between March 2017-February 2019. LWRs was estimated using the linear regression model. LWRs were obtained as total weight (TW) = 0.013L2.98, 0.057L2.40, 0.016L2.79 and 0.029L2.82 for C. macrostomus, G. rufa, B. lacerta and A.marmid, respectively. The b values acquired in the four fish species ranged from 2.13-2.57 (G. rufa-Male; Female) to 2.77-3.34 (B. lacerta-Female; Male). Only B. lacerta males had a positive allometric growth versus the males and females of all species had a negative allometric growth. The K of the fish species varied from 0.90-0.99 (A. marmid-Male; Female) to 1.27 (G. rufa-All), indicating that most of the fish were in good condition. However, C. macrostomus and G. rufa were better condition than B. lacerta and A. marmid. The study has provided baseline information on the LWR and K of the fish species in Göynük Stream. The data that would be useful to adapt the adequate regulations for sustainable fish stock estimation in the stream for fishery biologist. [ABSTRACT FROM AUTHOR]

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Invasive alien species pose a serious threat to biodiversity. They frequently compete with native species for resources, resulting in the decline or extinction of the latter.Native crucian carp (Carassius carassius) faces a severe decline in European waters and has become critically endangered in many European countries. Possible ecological mechanisms of the rapid decline of the crucian carp attributable to resource competition with the invasive Carassius gibelio were identified. A field study was combined with a controlled experiment to compare (i) standard length–weight relationships and growth patterns in 12 Czech and Swedish ponds in which the species occur alone or in syntopy, and (ii) individual growth and food utilization under the same conditions.The growth increment of C. gibelio was greater than that of C. carassius under the same experimental conditions (mean increase in weight: C. gibelio, 21.7%; C. carassius, 5.2%; increase in standard length: C. gibelio, 6.3%; C. carassius, 2.0%), suggesting that C. gibelio uses food resources more efficiently than C. carassius does. Moreover, larger C. carassius individuals did not grow, whereas growth of C. gibelio individuals was largely independent of standard length.Field data suggested that C. gibelio grew faster and were heavier than C. carassius of the same standard length in four Czech ponds where they occurred together. Individual weight‐at‐length declined in C. carassius in the presence of C. gibelio, especially in more dense populations, whereas the weight‐at‐length of C. gibelio remained similar.Taken together, these results imply that C. gibelio has better competitive abilities for food than C. carassius and provide novel support for the long‐standing hypothesis that the introduction and spread of C. gibelio causes the decline of C. carassius in European waters. [ABSTRACT FROM AUTHOR]

The Pseudohemiculter hainanensis (Boulenger, 1900) is a small Cyprinidae fish that has a wide distribution in China. In this study, we characterized the complete mitochondrial genome of P. hainanensis by the Illumina NovaSeq sequencing platform in Guangxi, China. The assembled mitogenome is 16,647 base pairs (bp) and consists of 13 protein-coding genes (PCGs), 22 transfer RNAs, two ribosomal RNAs, and a control region (D-loop). Nucleotide composition of the complete mitogenome is 29.69% (A), 24.82% (T), 27.97% (C), and 17.52% (G), with an A + T bias of 54.51%. The maximum-likelihood tree based on 13 PCGs showed that Pseudohemiculter hainanensis formed an independent lineage and P. hainanensis was closer to T. houdemeri. [ABSTRACT FROM AUTHOR]

Purpose: Myxozoans are economically important group of metazoan parasites, which can cause diseases in a large variety of commercially important fishes. Increased knowledge on molecular features has shown that traditional descriptive characters may be misleading. Combination of both descriptive and molecular features is therefore necessary for an integrated taxonomic assessment. Methods: Cyprinid Labeo batesii, sampled in the Makombè River at Nkondjock in Cameroon were examined for myxosporeans. Identification of parasite species was based on morphological and molecular sequence analyses of myxospores. Phylogenetic analysis was performed using maximum likelihood (ML) and Bayesian inference (BI) methods. Results: The scales of L. batesii were infected by Myxobolus nkondjockei sp. nov Their mature myxospores are ovoid in frontal view and lenticular in lateral view, with two rounded ends. These myxospores measured 10.3 (10–10.9) μm length and 8.0 (7.3–8.5) μm width. Myxospores have two ovoid and equal sizes polar capsules. They measured 4.5 (4.0–5.0) µm in length and 2.4 (2–2.9) µm in width. Polar tubules were coiled in 4–5 turns perpendicular to the longitudinal axis of the polar capsules. Phylogenetic analysis of the 18S rDNA sequence show clustering of M. nkondjockei sp. n. close to an undetermined species Myxobolus sp. reported infecting gill lamellas of Labeo rohita from India. Conclusion: The morphological, molecular and phylogenetic data provided for M. nkondjockei sp. n. are solid basis for further identification of this myxozoan of which pathogenicity probably plays an economic role at culturing the hosts. [ABSTRACT FROM AUTHOR]

The small cyprinid genus Prolabeops Schultz, 1941 is restricted to the Nyong and Sanaga River systems in Cameroon. In the past, the genus had been suggested to be either a member of the Labeoninae, Torinae or the Smiliogastrinae mainly on the basis of morphological similarities, and it is nowadays considered as incertae sedis within the Cypriniformes. This study provides the first attempt to reveal the phylogenetic position of Prolabeops using molecular data. For this purpose, the authors sequenced a large fraction of the mitochondrial genome (c. 13,600 bp), including all mitochondrial protein coding genes, of two Prolabeops melanhypopterus specimens and an additional four Enteromius specimens. The large‐scale phylogenetic analysis was based on an alignment including all mitochondrial protein coding genes of 902 specimens representing c. 899 cypriniform species. Prolabeops was clearly recovered within the African Smiliogastrinae, forming a weakly supported clade together with Enteromius jae, Enteromius hulstaerti and Barboides gracilis. The study data underline the urgent need of a thorough taxonomic revision of the small African barbs collectively placed in the genus Enteromius. [ABSTRACT FROM AUTHOR]

Some recent works have proposed that Capoeta ekmekciae from the Çoruh River and C. capoeta from the Kura‐Aras River system are synonyms based on molecular data, which prompted this study to compare their morphometric, meristic and molecular data to investigate this hypothesis. Based on the results, the C. ekmekciae form displays morphometric and meristic traits quite similar to the C. capoeta form. Since there are no diagnostic traits to distinguish these two allopatric species from each other and they share identical cytb gene, we treat C. ekmekciae as a junior synonym of C. capoeta. [ABSTRACT FROM AUTHOR]

The present study was conducted to determine the antibacterial resistance profile of Aeromonas hydrophila (n = 42) isolated from the 100 hemorrhagic septicemia‐suspected carp in Gilan, Iran. The prevalence of class 1 and 2 integrons, antibiotic resistance genes (ARG) and virulence factor genes (VFG) among these isolates was investigated using PCR. Also, the possible association between the presence of VFGs and the antibiotic resistance profile of isolates was assessed. The majority of A. hydrophila isolates (83·33%) exhibited multi‐drug resistance (MDR) profile, and all isolates were resistant to clindamycin, while all isolates were susceptible to amikacin. intI1 and intI2 gene was found in 26·2 and 4·8% isolates, respectively. This is the first report of the presence of the intI2 gene in A. hydrophila isolates in Iran. The blaTEM (40·5%) and tetA (33·3%) genes were found as the predominant ARGs. The most frequently detected VFGs were lip and ahh1(90·5%), while the examined isolates carrying at least three VFGs and the most prevalent VFGs profile was ast+, act+, alt+, ahhl+, aerA+, ahyB+ and lip+. The results of this study indicate a positive association between the presence of VFGs and antibiotic resistance, and most MDR A. hydrophila isolates showed high frequencies of VFGs. [ABSTRACT FROM AUTHOR]

Schizothorax eurystomus, Kessler 1872 is a unique economic fish in Xinjiang, China that is rarely seen in the market. Next-generation sequencing (NGS) was used to determine the complete mitochondrial genome of S. eurystomus collected from the Yarkand River in Xinjiang. The results showed that the mitochondrial genome is a circular, 16,488-bp-long nucleotide with the typical vertebrate genome structure of 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region. The termination-associated sequence (TAS), central conserved sequence block (CSB), and conserved sequence block were detected in the control region. Phylogenetic analysis placed S. eurystomus in a fully supported clade with S. biddulphi, and that clade was sister to S. yunnanensis. To our knowledge, this is the first study on the complete mitochondrial genome of S. eurystomus from the Yarkand River in Xinjiang, and it provides baseline genetic information for future studies. [ABSTRACT FROM AUTHOR]

Xenocyprinae is a cyprinid subfamily that not only has a discrete geographic distribution but also has a long history dating to the Early Miocene. However, it is controversial whether systematic classification and some species validity of Xenocyprinae exist, as well as its phylogenetic relationships and evolutionary history. In the present study, we first reviewed the description and taxonomic history of Xenocyprinae, and then the complete mitochondrial genome of Distoechodon compressus, an endemic and locally distributed species belonging to Xenocyprinae, was sequenced and annotated. Finally, all the mitogenomes of Xenocyprinae were compared to reconstruct the phylogenetic relationship and estimate the divergence time. The results showed that the mitogenomes are similar in organization and structure with 16618--16630 bp length from 12 mitogenomes of eight species. Phylogenetic analysis confirmed the monology of Xenocyprinae and illustrated three clades within the Xenocyprinae to consist of ambiguous generic classification. Plagiognathops is a valid genus located at the base of the phylogenetic tree. The genus Xenocypris was originally monophyletic, but X. fangi was excluded. Divergence time estimation revealed that the earliest divergence within Xenocyprinae occurred approximately 12.1 Mya when Plagiognathops separated from the primitive Xenocypris. The main two clades (Xenocypris and (Distoechodon + Pseudobrama + X. fangi)) diverged 10.0 Mya. The major divergence of Xenocyprinae species possibly occurred in the Middle to Late Miocene and Late Pliocene, suggesting that speciation and diversifications could be attributed to the Asian monsoon climate. This study clarifies some controversial issues of systematics and provides essential information on the taxonomy and phylogeny of the subfamily Xenocyprinae. [ABSTRACT FROM AUTHOR]

The mitochondrial genome plays a crucial role in the balance of energy and heat production in organisms and, thus, may be under natural selection due to its potential role in adaptive divergence and speciation. Here, we studied natural selection on the mitogenome of Acrossocheilus (Cypriniformes: Cyprinidae), a genus of fish that inhabits a broad latitudinal distribution ranging from the tropics and subtropics through temperate regions. Specifically, we used 25 published mitogenome sequences of Acrossocheilus species to investigate phylogenetic relationships in this genus and detected signals of positive selection on 13 protein-coding, mitochondrial genes. We found that relaxed purifying selection and genetic drift were the predominant evolutionary forces acting on the analyzed mitogenomes. However, we also found evidence of diversifying selection on some codons, indicating episodes of positive selection. Additionally, we analyzed the mitogenomic data within an environmental modeling framework and found that the Ka/Ks ratio of ATP6 may correlated with a mean diurnal temperature range (p = 0.0449), while the Ka/Ks ratio of COX2 may correlated with precipitation during the driest month (p = 0.00761). These results suggest that the mitogenomes of Acrossocheilus species may be involved in evolutionary adaptations to different habitats. Based on this, we believe that our study provides a new insight into the role of the mitochondrial genome of Acrossocheilus species in adaptation to different environments. During our study, we also discovered several cases of paraphyly and polyphyly among accessions of species and their putative synonyms. Thus, our study suggests that a careful reassessment of the taxonomy of Acrossocheilus is using high-quality molecular data merited. [ABSTRACT FROM AUTHOR]

The endocrine disruptor chemicals (EDCs) are ubiquitous in the environment, and it has raised wide public concern because of the dangers of EDCs for living organisms and the environment. In order to comparatively study the effects of EDCs [17-α-ethinylestradiol (EE2), Bisphenol A (BPA) and Nonylphenol (NP)] on the expression of estrogen receptors (ERs: erα,erβ1, and erβ2) at mRNA and protein level, total 520 adult Tanichthys albonubeswere exposed to E2,EE2, BPA and NP with three concentrations respectively: EE2 (1, 5, 25 ng/l), NP (10, 50, 250 μg/l), BPA (100, 500, 2,500 μg/l) for 28 days, E2 (2, 20, 200 ng/l) being as the positive control. After treatment, the brain, eye, gill, heart, liver, gut, kidney, muscle, testis, and ovary were collected, following by the real-time quantitative PCR (RT-qPCR) andwestern blotmethods to detect the expression levels of erα, erβ1, and erβ2 in T.albonubes at mRNA and protein level. Our results showed that high expression of terα (t means T.albonubes), terβ1, and terβ2 were detected in liver, while terβ1 and terβ2 mainly expressed in the liver, intestine, kidney, muscle and testis. EE2, BPA, and NP treatment all up-regulated the expression of terα, terβ1, and terβ2 in the brain, liver, and testis, but with some variations. Similar to mRNA level, both TERα and TERβ were up-regulated by all the EE2, BPA, and NP treatment with dose-dependent effect. In conclusion, the responses of ERs of T.albonubes to the EDCs present measurability and susceptibility, which make it possible for T. albonubes to be an efficient biomarker to monitor and evaluate the pollution of endocrine disrupting chemicals in water environment. [ABSTRACT FROM AUTHOR]

Skeletal development is essential in supporting aquaculture success, as failure and deformities reduce fish viability and growth. Herein, the cartilage and bone formation in the larva and juvenile of the bonylip barb, Osteochilus vittatus (Valenciennes, 1842), is described in detail for the first time. Mature fish were injected with ovaprim at 0.5 mL.kg-1 body weight, followed by artificial spawning. After fertilisation, the embryos were reared in a glass container at 28 ± 1 °C. The first hatchling was observed at 26 h and 15 min post-fertilisation (pf), and the last was observed at 48 hpf. The cartilage and bone development were observed from 1 to 30 days post-hatching (dph) by alcian blue and alizarin red S staining. Freshly hatched fish larvae had not undergone either chondrification or ossification. The cartilage was observed at 1 dph, marked with Meckel's cartilage, ethmoid plate, and pectoral fin, as the pre-larva had a standard length (SL) of 5 mm. At 5 dph (SL of 5.6 ± 0.55 mm), 3 to 4 pairs of basidorsal and basiventral were observed. The cartilaginous development ended at 26 dph as the SL reached 14.3 ± 0.57 mm. The ossification started at 20 dph (SL of 9.24 ± 0.68 mm) and was marked with opercle and cleithrum. At 26 dph, as the post-larvae length 14.3 ± 0.57 mm, dentary, pterotic, and parasphenoid were ossified. Juvenile fish at 30 dph (SL of 21.2 ± 3.9 mm) showed completed ossification processes in the cranium and vertebrae. [ABSTRACT FROM AUTHOR]

Environmental flow of the Beshar River was evaluated using Tennant's hydrological method, the comparison of the depth and speed of the water in the transverse sections of the river, and the needs of indicator fish species in different stages of the life cycle. Field samplings were conducted in October and January 2021 to monitor the status of fishes in the Beshar River and to collect cross-sections of the river. Indicator species were selected based on the expert judgement survey method. Among 23 fish species of the Beshar River, five species from the Cyprinidae family recieved the highest scores. The biological requirements of these species were extracted and used as the basis of comparison with the data of cross sections of the river. The obtained results showed that in the upper reaches of the river (between the two hydrometric stations of Qalat and Shah Mokhtar) the good class of the Tennant method, that includes 40% of the average annual discharge for the period of high flow (April to May) and 20% of the average annual discharge for the period of low flow (June to November), is suitable to provide the biological requirements of adult and larva of cyprinid species of the Beshar River, respectively. [ABSTRACT FROM AUTHOR]

To assess aquatic toxicity of natural wetlands in the Athabasca oil sands region (AOSR) of northern Alberta, fifteen collected water samples were tested for their ability to affect survival and development of fathead minnow embryos. Wetland waters were also assessed for toxicants from natural oil sands bitumen deposits (Na, Cl, metals, naphthenic acids (NAs), naphthenic acid fraction compounds (NAFCs), polycyclic aromatic hydrocarbons (PAHs), and alkylated PAHs). Water samples from four wetlands caused toxicity to fish embryos. The most potent wetland water, HAT-S5, caused significantly decreased hatch success, decreased time-to-hatch, decreased embryonic heart rate and increased deformities (60 % vs controls 2 %). Exposure to wetland waters from Saline Lake (where conductivity was 2320 μS/cm and Na was high) resulted in fish with increased deformities (58 % vs controls 2 %) that were not the results of high conductivity alone. Two other wetland waters (Gateway Bridge and Crane Lake) also disrupted development in fathead minnow embryos. These combined findings suggest that for natural wetland waters causing effects in fish embryos, toxicants other than salinity/conductivity/ions were responsible for the observed effects. The general water chemistry of most wetlands was unremarkable. However, the most potent wetland, HATS5-wtl is a naturally occurring wetland with possible connections to ground water that makes contact with bitumen. The assessment of the toxicity and chemicals present in natural wetlands provides background data for future studies and for design of restoration wetlands for oil sands mining-disturbed landscapes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2024. Published by Elsevier B.V. All rights reserved.)

The current work was conducted to investigate fisheries dynamics, rate of growth, and mortality, along with demographic features of Schizothorax niger using length-frequency data collected monthly from Manasbal Lake from August 2020 and July 2022. The length data for estimation was categorized into 13 bins, and population parameters were explored utilizing various options in ELEFAN I, with the best fit (Rn = 0.282) calculated by means of the FiSAT-II application. TW = 1.94 TL 2.94 , with a =  - 1.94, b = 2.94, and an attuned r 2  = 0.77 were derived for the weight and length association. The growing performance metric (ϕ) was calculated as 2.80. S. niger harvested stock in Manasbal Lake was prevalent in length categories of 20.5 to 25.4 and 25.5 to 30.4 cm. Different growth attributes were valued utilizing length frequency statistics as L ∞  = 46.05 cm, k = 0.30/year, and t 0  =  - 0.493 years. Over all mortality (Z), natural mortality (M), and fishing mortality (F) coefficients were evaluated as 1.43 year -1 , 0.56 year -1 , and 0.87 year -1 , respectively. The fish's average length was assessed at the culmination of the 1st, 2nd, 3rd, 4th, 5th, and 6th year as 15.42 cm, 22.78 cm, 28.09 cm, 32.61 cm, 36.03 cm, and 38.53 cm, respectively. Recruitment patterns in S. niger from Manasbal Lake indicate a singular annual recruitment occurrence, exclusively observed during the month of June. The current value of the exploitation (fish harvest) ratio (E) was 0.61 by the size-transformed catch curvature method, found to be marginally lower than the maximum value (E max ) of 0.699 depicting that the species is on the brink of overexploitation, and caution is required to maintain sustainability. The seasonal analysis of water quality parameters revealed that except for pH and free carbon dioxide, the other parameters showed pronounced temporal variations. Total alkalinity values were reflective of hard water type of the lake, and dissolved oxygen and free carbon dioxide values were reported to be suitable for S. niger., Competing Interests: Declarations. Ethical approval: All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors. Competing interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The present study rigorously examined the toxicological effects of nanoparticles (NPs), specifically nickel (Ni) and chromium oxide (Cr 3 O 4 ) NPs, synthesized under controlled conditions and characterized. To evaluate their potential environmental impact exposed the freshwater fish Labeo rohita ( L. rohita ) to environmentally relevant concentrations of both NPs within a controlled laboratory conditions. Vital organs, including gills and liver were subjected to histopathological analysis, revealing profound alterations in tissue architecture that were distinctly correlated with pathological damage. The lesions exhibited moderate to severe changes that are further correlated with the semi-quantitative mean alteration value (MAV). Furthermore, conducted a quantitative assessment of tissue-specific morphological changes. Notably, there was a significant reduction in critical hematological changes, including red blood cell (RBC) and white blood cell (WBC) counts, hemoglobin concentrations and other parameters. All of which exhibited significant fluctuations in relation to increasing NPs concentrations. These findings underscore the critical necessity for continued investigation into the ecological risks associated with these nanoparticles.

Aspirin is one of the most frequently detected non-steroidal anti-inflammatory drugs in aquatic environments. Despite its prevalence, toxicity possessed by aspirin to non-target organisms like fish is poorly explored. In the present study, cell death induced by different concentrations of aspirin (1, 10, and 100 µg/L) has been investigated in the liver of fish, Labeo rohita exposed for 28 days. A significant increase (p < 0.05) in the density of caspase-3 positive cells in a dose and duration-dependent manner assessed through immunofluorescent staining indicates caspase-dependent pathway of cell death which may be either through intrinsic or extrinsic pathway. The flow cytometric analysis, in addition, revealed a significant (p < 0.05) decline in the live cells and an increase in apoptotic cells in the liver of fish exposed to aspirin. Cell death due to apoptosis is further indicated by a significant increase (p < 0.05) in the Kupffer cells and tumor necrosis factor-α. The decrease in the activity of cyclooxygenase (COX) enzyme significantly (p < 0.05) in all three exposure concentrations of aspirin suggests COX-dependent pathway of cell death. The present study provides in-depth insights into aspirin-induced cell death in the liver of fish at environmentally realistic concentrations., Competing Interests: Declarations Ethical approval The experiments were carried out under the guidance of ethical regulations from the institutional animal care and use committee (Ref No. BHU/DoZ/IAEC/2021–2022/022, dated 15/02/2022). Consent to participate and consent to publish All the authors have equally participated in this study and agreed to publish this work in this journal. Competing interest The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

This study aimed to investigate the effects of dietary metformin supplementation on the redox balance, inflammation, mitochondrial biogenesis, and function in blunt snout bream fed a high-carbohydrate (HC) diet. Fish (45.12 ± 0.36 g) were randomly offered four diets, including a control diet (33% carbohydrate), an HC diet (45% carbohydrate), and the HC diet supplemented with 0.06% (HCM1) and 0.12% (HCM2) metformin respectively for 12 weeks. Compared with the control, feeding the HC diet significantly increased the hepatosomatic index (HSI), the mesenteric fat index, liver and muscle glycogen contents, liver and adipose tissue lipid contents, plasma glucose and glycation end products (AGES) levels and aspartate transaminase activity, plasma and liver malondialdehyde (MDA) contents, hepatic adenosine triphosphate (ATP) and adenosine monophosphate (AMP) contents, mitochondrial cytochrome c content, mitochondrial complex IV activity and ATP 6 transcription, but decreased plasma catalase (CAT) activity, muscle superoxide dismutase (SOD) activity, hepatic antioxidant enzymes activities, and the transcriptions of transforming growth factor β (tgfβ) and interleukin 10 (il10). Compared with the HC group, metformin treatment (especially the HCM2 group) significantly elevated tissue glycogen contents, muscle SOD activity, plasma and liver antioxidant enzymes activities, the transcriptions of tgfβ and il10, the sodium/potassium ATPase activity, the contents of mitochondrial protein and AMP, the level of p-AMP activated protein kinase (AMPK), and the p-AMPK/t-AMPK ratio, but lowered the HSI, tissue lipid contents, plasma levels of glucose, AGES and glycated serum protein, plasma, and liver MDA contents, the transcriptions of il1β, NADH dehydrogenase subunit 1 and ATP 6, the contents of ATP and cytochrome c, the ATP/AMP ratio, and the activities of complexes I and IV. In conclusion, metformin could attenuate the HC diet-induced redox imbalance, inflammation, and mitochondrial dysfunction in blunt snout bream., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Industrialization and the extensive use of chemicals have raised significant concerns about their environmental impacts, particularly on aquatic ecosystems. This study evaluated the sub-lethal effects of Celcron (Cec), an organophosphate insecticide, on the Java barb (Barbonymus gonionotus) through erythrocyte morphology and acetylcholinesterase (AChE) activity, aiming to refine biomarkers for environmental health assessments. We hypothesized that sub-lethal Cec exposure would induce significant erythrocyte abnormalities and decrease AChE activity in Java barb, with variable recovery rates between gill and kidney tissues. To test this, we exposed the juvenile Java barbs to two sub-lethal Cec concentrations - 0.01 ppm (10 % of the LC 50 ) and 0.05 ppm (50 % of the LC 50 ) -for 60 days. After the exposure period, the fish were placed in pesticide-free water to allow for recovery. Results indicated a significant decline in AChE activity in both liver and kidney tissues, with activity levels showing gradual recovery over time. Erythrocyte abnormalities, including nuclear and cellular changes, were significantly elevated in response to Cec exposure. The frequency of nuclear abnormalities such as micronuclei and binucleation increased in a concentration- and duration-dependent manner, with the gill blood exhibiting higher sensitivity and slower recovery compared to kidney blood. Cellular abnormalities such as twin, teardrop and spindle-shaped cells were also more prevalent in Cec-treated fish. Recovery from these abnormalities was observed but varied between gill and kidney blood, with gill blood showing higher sensitivity and slower recovery compared to kidney blood. This study underscores the utility of AChE activity and erythrocyte abnormalities as biomarkers for assessing pesticide impacts on aquatic organisms. The findings highlight the sensitivity of fish erythrocytes to environmental contaminants and emphasize the need for continued research to better understand the long-term effects of pesticide exposure on aquatic health and ecosystem stability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Assessing the environmental risks of contaminated groundwater presents significant challenges due to its often-complex chemical composition and to dynamic processes affecting exposure of organisms in receiving surface waters. The objective of this study was to characterize the effects of groundwater collected from a legacy contaminated industrial site, in fish under environmentally relevant conditions. A 21-day fish short-term reproduction assay was conducted in outdoor wetland mesocosms by exposing adult fathead minnows (Pimephales promelas) to graded concentrations of groundwater (1 %, 3 %, and 6 %). Offspring were held in mesocosms up to four days post-hatch to apply a new approach method (NAM), the EcoToxChip™, to explore whether traditional apical endpoints could be predicted using an alternative mechanistic approach. None of the groundwater concentrations used in this study were lethal to fish. There was greater cumulative number of eggs produced at the highest concentration of exposure. However, no abnormal histological appearance was observed in the liver and gonads of fish and no significant effect was observed in the relative expression of genes, tubercle counts, and erythrocyte micronuclei counts compared to the negative control. Food availability in the mesocosms was also assessed and the abundance of zooplankton increased in all groundwater-treated mesocosms. Fathead minnow findings are in contrast to those obtained from previous controlled laboratory studies that revealed significant genotoxicity, hepatotoxicity, and reprotoxicity of the same mixtures. Several factors could explain these observations, including the aging of groundwater in mesocosms before fish addition resulting in photo- and biodegradation and binding to sediments of toxic components. Our static exposure scenario likely underestimated realistic exposure scenarios where groundwater inflow to surface water is generally semi-continuous. Nevertheless, focused transcriptome analysis using EcoToxChips also observed greater toxicity during previous laboratory tests compared to mesocosm scenarios, and thus, our results support the use of this NAM in the ecological risk assessment of contaminated groundwater., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Laura Gasque-Belz reports financial support was provided by Natural Sciences and Engineering Research Council of Canada and the industry partner. The author (s) acknowledge the potential conflict of interest due to funding received from the industry partner and owner of the study site for this research project. However, for the present study they had no role in study design, in the collection, analysis and interpretation of data and in the writing of the report., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The current study evaluated the efficacy of Moringa oleifera leaf extract in mitigating the histo-biochemical alterations in Labeo rohita caused by arsenic. A medical plant (Moringa oleifera) known for its numerous pharmacological qualities, was added to three different diets at 0, 2, and 4 % level, prepared by mixing M. oleifera leaf extract with the basal diet. The 96 hr lethal concentration of arsenic to Labeo rohita was 20.25 mg L -1 . One hundred and eighty healthy individuals of Labeo rohita were divided into four groups. One group served as control and other three groups were subjected to sub-lethal concentration 4.05 mg L -1 (1/5th of LC 50 ) of arsenic, with or without Moringa oleifera leaf extract supplementation for 28 days. Fish exposed to arsenic experienced significant histological alterations, higher cortisol levels, impaired antioxidant status, elevated liver enzymes (ALT, AST, and ALP), and upregulated relative expression of the cytochrome P450 gene.". But, in fish fed with diets containing 2 % or 4 % M. oleifera leaf extract, the histological alterations were reduced, level of liver enzymes, cortisol and the upregulation of anti-oxidant enzyme and cytochrome P450 gene expression was normalized, with (4 %) M. oleifera leaf extract supplemented diet exhibiting stronger effects. These results suggest the protective and therapeutic roles of M. oleifera as a feed supplement in Labeo rohita against arsenic induced toxicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Grass carp ( Ctenopharyngodon idella ) is a Cyprinid fish of aquacultural and research importance. The buccal cavity represents the gateway of the digestive tract. The present study investigated the adaptational changes involving various components of the buccal cavity of fingerling (three months posthatching, mph), yearling (12 mph), and adult (48 mph) C. idella using scanning electron microscopy, histology, and morphometry. The upper and lower lips appeared uninterrupted at the three studied stages and were limited caudally by the upper and lower jaws. The jaw epithelium was the thickest part of the buccal epithelium; ultrastructurally, it appeared smooth with ridge-like borders in fingerlings that transformed into microgrooves in yearlings. In adult C. idella , the jaw mucosa was organized into dome-shaped masses separated from each other by tight furrows. Each mass was formed from several keratinocytes with corrugated surfaces that featured numerous microdepressions. Except for the jaws, taste buds, mainly of type I, and acidic and neutral goblet cells were observed throughout the mucosa of the buccal cavity, and their densities were highest along the mucosal folds of the palate and oral floor, suggesting a principal role for these parts in both gustation and food lubrication. This study is the first to report age-associated spatiotemporal changes in the buccal cavity of grass carp and will serve as a fundamental reference during the interpretation of various types of oral pathologies in teleost.

This study evaluated drinking water treatment residuals (DWTR) as an in-situ capping material for metal-contaminated sediments using Gust-chamber experiments. Metal release from non-capped and DWTR-capped sediments was measured under increasing shear stress (τ) from 0.05 to 0.4 Pa. Fathead minnow (FHM) juveniles (Pimephales promelas) were exposed to water from these sediments in 96-h bioassays to assess DWTR's efficacy in reducing metal toxicity. Sand was used as an inert capping material for comparison. Diffusive gradients in thin films (DGT) assessed DWTR's impact on vertical metal concentration profiles in sediment pore water and overlying water, with concentrations determined by ICP-MS. Without capping, increasing τ raised metal concentrations in the overlying water from 45 to 95 mg/L for Cd and Zn, 4-10 mg/L for Cu, and 2-4 mg/L for Pb. Sand capping reduced these levels, with Cd and Zn ranging from 4 to 21 mg/L, Cu from 0.26 to 0.63 mg/L, and Pb from 0.051 to 0.23 mg/L. DWTR capping significantly lowered metal concentrations in the overlying water, with Cd ranging from 1 to 8 μg/L, Zn from 30 to 40 μg/L, Cu from 2.5 to 5 μg/L, and Pb from 1 to 2 μg/L. Therefore, beyond the physical barrier effect, the DWTR cap immobilizes metals through other mechanisms such as sorption and precipitation. Bioassays showed that DWTR significantly decreased metal toxicity to FHM, while sand-capped and non-capped sediments caused 100% mortality. DGT confirmed DWTR reduced metal fluxes at the sediment-water interface by up to two orders of magnitude., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Cypermethrin is a pyrethroid insecticide used in aquaculture farms against ectoparasites. The conventional pesticide formulations are now being found to be greatly ineffective at low dosages, and their indiscriminate usage may cause undesired effects in ecosystems. So, the current study was designed to develop a nanoformulation of cypermethrin that would have many advantages over conventional pesticide formulations, and the toxic effects of this formulation were then tested on the carp Labeo rohita fingerlings. The 96-h LC 50 was estimated at 0.018 mg L -1 after the acute toxicity study. Chronic toxicity studies were carried out, exposing the fish to two sublethal doses via 1/10th (C1) and 1/50th (C2) of 96-h LC 50 for a period of 45 days. The nanoformulation exposure caused a significant reduction in the brain AChE enzyme activity. Catalase and glutathione-s-transferase enzyme activity in the gills and liver increased significantly, as did superoxide dismutase enzyme activity in the kidney. Serum total protein, triglycerides, cholesterol, and some serum enzyme activities decreased. In contrast, white blood cells, red blood cells, haemoglobin, and hematocrit levels decreased only in fish exposed to a higher dose. As baseline information, these findings may aid in understanding the toxic effect of nanoformulated cypermethrin on finfish., Competing Interests: Declarations. Ethical approval: The manuscript is not submitted to any other journal. The present work complies with the ethical guidelines of the National Research Council’s Guide for the Care and Use of Laboratory Animals, with the permission of the Institutional Animal Ethics Committee, constituted by the ICAR-Central Inland Fisheries Research Institute, Kolkata, India. Consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Economy of Pakistan is heavily dependent upon agriculture and extensive use of pesticide is quiet common to enhance the crop yield. Imidacloprid is among the first choice pesticides in Pakistan and it has been reported that through run off along with water it ends up in water bodies affecting non target aquatic fauna. Through the present investigation, we are reporting the effects of Imidacloprid on the fatty acids composition of a non-target, commercially important carp: Labeo rohita . Fish were exposed to sub lethal concentration of Imidacloprid (120 mgL 1 ) for 2, 4 and 8 days (short term) as well as for 16, 32 and 64 days (long term experimental conditions). Pesticide untreated controls were also maintained for each treatment. Following the specific Imidacloprid exposure, fatty acid composition (%) was determined in the muscle of all experimental groups by using gas chromatography. Fish exposed to Imidacloprid for 8 days had reduced Palmitic acid ( p  = 0.02) and elevated muscle Arachidic acid ( p  < 0.001) than control group. Labeo rohita exposed to the pesticide for 32 days had elevated muscle Oleic ( p  = 0.02) and Linoleic acid ( p  = 0.02) while fish exposed to Imidacloprid to 64 days had reduced muscle Palmitic ( p  = 0.04) and Oleic acid ( p  = 0.03). In conclusion, we are reporting that the exposure to sub lethal concentration of Imidacloprid disturb the muscle fatty acid composition of Labeo rohita that may affect its food quality. The effects were more pronounced under long term experimental conditions and were probably due to potentiating lipid peroxidation and disturbed fish metabolism upon Imidacloprid exposure.