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Crucian carp (Carassius auratus) is widely distributed in the world and has become an economically freshwater fish. The population in Lake Dali Nur can tolerate the extreme alkaline environment with alkalinity over 50 mmol/L (pH 9.6), thus providing a special model for exploring alkali-tolerant molecular markers in an extremely alkaline environment. In this study, we constructed a high-density and high-resolution linkage map with 16,224 SNP markers based on genotyping-by-sequencing (GBS) consisting of 152 progenies and conducted QTL studies for alkali-tolerant traits. The total length of the linkage map was 3918.893 cM, with an average distance of 0.241 cM. Two QTLs for the ammonia-N-tolerant trait were detected on LG27 and LG45. A QTL for the urea-N-tolerant trait was detected on LG27. Interestingly, mapping the two QTLs on LG27 revealed that the mapped genes were both located in the intron of CDC42. GO functional annotation and KEGG enrichment analysis results indicated that the biological functions might be involved in the cell cycle, cellular senescence, MAPK, and Ras signaling pathways. These findings suggest that CDC42 may play an important role in the process of dealing with extremely alkaline environments. [ABSTRACT FROM AUTHOR]

Due to high-density farming methods and poor farming environments, freshwater fish often have poor muscle texture and a fishy odor before marketing, which impacts consumer acceptance. Short-term low-salinity seawater treatment of freshwater fish before marketing has been found to improve the quality of the fish, but the mechanisms underlying this phenomenon have not yet been revealed. In this study, metabolomics technique was used based on gas chromatography-mass spectrometry (GC–MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) to screen different metabolites and predict potential metabolic pathways after treatment with low-salinity seawater. The results showed that 3838 metabolites were presented in all of the carp samples, while 62 and 64 differential metabolites were found in the comparative groups (FW, SW, and CK represented freshwater, seawater and non-transient group, respectively). Additionally, 25 and 26 metabolic pathways were enriched from these groups. Glutaric acid, PC, and creatinine might be potential biomarkers. Seawater aquaculture significantly altered the lipid metabolism, nucleotide metabolism, and amino acid metabolism of carp, enhancing its freshness and having a significant impact on its quality. This study provided insights into the metabolic changes in carp under different rearing conditions and also served as a theoretical basis for salinity treatment before freshwater fish are brought to the market. [ABSTRACT FROM AUTHOR]

The coexistence of sexual and asexual lineages is rarely documented in vertebrates. Various ecological and evolutionary mechanisms have been proposed to explain their stable coexistence. Gibel carp (Carassius gibelio), a highly invasive freshwater fish in Europe, is one such example of a sexual and asexual vertebrate, combining gynogenesis (sperm-dependent parthenogenesis) and sexual reproduction. In this study, we focused on vigour-related traits in gynogenetic and sexual forms of gibel carp coexisting in the same habitat, to reveal whether there is a link between parasite load and vigour-related traits reflecting the potential advantage of one reproductive form over another, which may eventually facilitate the obligatory coexistence of sperm-dependent gynogenetic females with sexual males. Using physiological parameters (indexes of somatic condition, energetic condition, and reproductive performance; glucose levels; and erythrocytes-related variables), diploid sexual males, diploid sexual females, and triploid gynogenetic females were found to be differentiated from one another. However, based on immune variables representing innate immunity, specific immunity, and index of immunocompetence, mostly sexual males were found to be weakly differentiated from both groups of females. We revealed different patterns of interactions between parasite abundance and immune variables between sexual and gynogenetic forms. Using parasite assemblage composition, different relationships between parasite assemblage and immunity or physiology in sexual males and sexual females were evidenced, potentially related to male reproduction biology. In contrast, gynogenetic females exhibited the advantage that parasite assemblage composition did not affect their immunity or physiology. Our study suggests that reproduction mode-associated costs of physiology and immunity may facilitate the coexistence of the asexual-sexual complex. We highlight that multiple ecological processes and evolutionary mechanisms contribute to the coexistence of asexual and sexual gibel carp. [ABSTRACT FROM AUTHOR]

In the scope of this study, fish fauna of Küçük Menderes River and its tributaries, updated with the comparison of the recent ichthyofaunal studies, as well as the length-weight relations (LWR) and condition factors (CF) were estimated for 7 freshwater fish species belonging to six families from the river basin: endemic Oxynoemacheilus eliasi, Cobitis fahireae; invasive, Carassius gibelio, Atherina boyeri, transloce Perca fluviatilis and the native Squalius fellowesii, Cyprinus carpio. The fish samples were collected with various fishnets and DC electro-fishing devices from six stations in 2018 and 2019. The LWR of the fishes was studied based on 379 specimens. The estimated values of parameter b ranged from 2.884 (A. boyeri) to 3.176 (C. fahireae). The coefficient of determination (R2) was changed between 0.792 to 0.980 for all sampling localities. In the study, Fulton's condition factor ranged between 0.391 (S. fellowesii) to 3.080 (S. fellowesii); the relative condition factor ranged between 0.346 (O. eliasi) to 2.746 (S. fellowesii), respectively. This research is anticipated to contribute valuable insights for the conservation of the species, while also furnishing essential data to inform future fisheries management studies in the region. [ABSTRACT FROM AUTHOR]

For the period 2019-2021, an ecoparasitological study of six fish species - grass carp (Ctenopharyngodon idella Valenciennes, 1844); silver carp (Hypophthalmichthys molitrix Valenciennes, 1844); pumpkinseed (Lepomis gibbosus Linnaeus, 1758); Prussian carp (Carassius gibelio Bloch, 1782); gudgeon (Gobio gobio Linnaeus, 1758); European bitterling (Rhodeus amarus Bloch, 1782) was conducted. The fish were caught from 3 biotopes (Koshava, Kudelin, Novo selo) from the upper section of the Danube River in Bulgaria. A total of two parasite species (Pomphorhynchus laevis Zoega in Müller, 1776) Porta, 1908 and Contracaecum sp. (larvae) were found in two of the investigated fish species. Four fish species were not infected. The ecological indices (mean intensity; mean abundance; prevalence) of parasites were calculated. Kudelin and Koshava biotopes are new habitats for the found helminth species of the infected fish species. [ABSTRACT FROM AUTHOR]

The freshwater bivalve Anodonta woodiana is native to China and widely distributed in Asia, Europe, and North America. However, natural populations of A. woodiana in China have dramatically declined recently. Several fish species have been used as potential hosts in breeding programs; nonetheless, the optimal host species is yet to be identified. In this study, we examined the suitability of five potential host fish species (bighead carp, common carp, crucian carp, yellow catfish, and tilapia) for A. woodiana under laboratory conditions. No significant difference was found in the number of glochidia attached to the five fish species; however, tilapia hosted more transformed juveniles than bighead carp, common carp, or yellow catfish (p < 0.05), with bighead carp hosting the least (p < 0.05). Yellow catfish had the highest host capacity index (the number of successfully transformed juveniles/the weight of the host fish × the survival rate of the host fish), 133 times higher than bighead carp and 1.3–2.9 times higher than the other species. The shell length and height of freshly transformed juveniles from yellow catfish were significantly larger than those of other host fish (p < 0.05). The juvenile index (shell length × shell height) of yellow catfish was significantly higher than that of other fish species (p < 0.05). In conclusion, yellow catfish appears to be the most suitable host fish out of the five species tested here. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the relationships between total length and weight (L - W), to estimate the growth parameters (von Bertalanffy) L∞, k, and the mortality rates (Z, M, F) for the common carp (Cyprinus carpio, Linneaus, 1758) and Prussian carp (Carassius gibelio, Bloch, 1782). Sampling was carried out monthly, from March to September 2021. The relationship between length - weight (L - W) in the study period for common carp was W=0.0574×Lt2.6437, respectively W=0.0391× Lt2.7831 for Prussian carp. The growth parameters for common carp were L∞=86.10 cm and K = 0.87 per year, respectively L∞= 40.95 cm and K 0.67 per year, for Prussian carp. The total (Z), natural (M) and fishing (F) mortality rates were 1.47, 0.82 and 0.65 per year, for common carp, respectively Z=1.65, M=0.85 and F=0.80 for Prussian carp. Regarding the exploitation rate (E) this was 0.44 for the common carp population, respectively 0.48 for Prussian carp, suggesting that both fish population were not in over-exploited condition. [ABSTRACT FROM AUTHOR]

This study aimed to investigate nutrition in climbing perch Anabas testudineus which is an important nutritious economic freshwater fish in Asia and compare with Carassius auratus (crucian carp). Three kinds of tissues, including muscle, livers, and eggs, were isolated, respectively. Physicochemical properties including moisture, ash, protein, amino acids, fat, vitamins, and calcium contents in those tissues were determined. The results showed climbing perch muscle and liver contained less moisture, but more protein, amino acids, and vitamins than crucian carp muscle and liver. While moisture, ash, protein, and total amino acids contents of climbing perch egg were lower than those of crucian carp egg. Climbing perch egg had more fat, vitamins, and calcium than crucian carp egg. The amino acid profile was also performed, and 16 amino acids were identified and quantified in muscle, liver, and egg. Among tissues, the highest and lowest concentration of total amino acid content was found in crucian carp eggs and livers, respectively. Glutamic acid (Glu) and histidine (His) were the most and least amino acids in climbing perch and crucian carp tissues, respectively. Sixteen amino acids in climbing perch egg were less than those in crucian carp egg while it is an opposite case in muscle and liver, which amino acids of climbing perch tissues were more than those of crucian carp muscle and liver. Vitamin A of climbing perch was more than crucian carp in all three tissues, but vitamin E content in climbing perch liver was lower than that of crucian carp liver. Calcium content of muscle had no difference between two species. The abovementioned comparison of physicochemical properties of different tissues from China climbing perch and crucian carp will provide a necessary supplementary of freshwater muscle nutrition research, also was helpful for application of climbing perch. [ABSTRACT FROM AUTHOR]

Throughout 2016 - 2021, a series of experimental studies on 137Cs uptake and excretion rate constants for the silver Prussian carp (Carassius gibelio) were conducted in the Chornobyl exclusion zone (ChEZ) under natural conditions. To confirm the metabolic parameters of 137Cs in the silver Prussian carp under strictly controlled conditions at different feed amounts real supporting laboratory experiments have been conducted. The excretion rate of the 137Cs from the silver Prussian carp increased with increasing feed amount from 0.0068 ± 0.0003 day−1 to 0.0085 ± 0.0005 day−1 at water temperatures of 26 °C. The biological half-life of 137Cs activity concentration in fish can be reduced by 2 times by increasing fish growth using clean feeding. The excretion rate of the 137Cs from the silver Prussian carp agreed with data collected in natural conditions in the ChEZ during 2016 - 2020 at different water temperatures. [ABSTRACT FROM AUTHOR]

Both adult females and males of Argulus mongolianus Tokioka, 1939 were collected from the buccal cavity wall and body surface of freshwater fishes in Lake Izunuma and Lake Uchinuma, Miyagi Prefecture, northen Honshu, Japan. The original description of the species was insufficient, based on a single female from Inner Mongolia, China, and no further description has been made to date. Thus, this paper redescribes A. mongolianus based on the newly-collected specimens, including the first description of the male. This represents the first record of A. mongolianus from Japan. The infected fishes were largemouth bass, Micropterus salmoides (Lacepède, 1802), common carp, Cyprinus carpio Linnaeus, 1758, Japanese white crucian carp, Carassius cuvieri Temminck and Schlegel, 1846, and silver crucian carp, Carassius sp. The three species other than common carp are new host records for A. mongolianus. This parasite was most probably introduced with an unspecified freshwater fish from China into Japan. [ABSTRACT FROM AUTHOR]

Individual variations in metabolic rate, locomotion capacity and hypoxia tolerance and their relationships were investigated in three cyprinid species [crucian carp (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis), in 60 individuals of each species]. Either the active metabolic rate (AMR) and critical swimming speed (Ucrit) (30 individuals) or critical oxygen tension (Pcrit) and loss of equilibrium (LOE) (30 individuals) were measured in each species after measuring the resting metabolic rate (RMR). Both the AMR and Ucrit were found to be significantly and positively correlated with the RMR in all three cyprinid species, indicating that high-RMR individuals have high aerobic capacity and thus good swimming performance. Pcrit was positively correlated with the RMR in all three species, whereas the LOE was highly positively correlated, weakly positively correlated and not correlated with the RMR in qingbo, common carp and crucian carp, respectively, possibly due to specialized morphological and biochemical adaptations involved in hypoxia tolerance in crucian and common carp. Crucian carp showed relatively poor swimming performance, i.e., a low Ucrit (relatively high variation), strong hypoxia tolerance, and low LOE (relatively low variation); qingbo showed relatively good swimming performance (relatively low variation) and weak hypoxia tolerance (relatively high variation); and common carp showed moderate swimming performance and relatively strong hypoxia tolerance (moderate variation). These interspecific differences may be due to the different lifestyles of these cyprinid fishes based on their associated fast–slow-flow regime and are outcomes of long-term selection. [ABSTRACT FROM AUTHOR]

• The metabolism of diet As was investigated in food fish during chronic exposure • Arsenic adaption involved reduced As bioaccumulation and increased As biotransformation • The bioavailability of dietary arsenite was lower than that of arsenate • Arsenite was largely formed in fish muscle at earlier stage of arsenate exposure Dietary uptake is the major way that inorganic arsenic (iAs) enters into benthic fish; however, the metabolic process of dietborne iAs in fish muscle following chronic exposure remains unclear. This was a 40-day study on chronic dietborne iAs [arsenite (AsIII) and arsenate (AsV)] exposure in the benthic freshwater food fish, the crucian carp (Carassius auratus), which determined the temporal profiles of iAs metabolism and toxicokinetics during exposure. We found that an adaptive response occurred in the fish body after iAs dietary exposure, which was associated with decreased As accumulation and increased As transformation into a non-toxic As form (arsenobetaine). The bioavailability of dietary AsIII was lower than that of AsV, probably because AsIII has a lower ability to pass through fish tissues. Dietary AsV exhibited a high potential for transformation into AsIII species, which then accumulated in fish muscle. The largely produced AsIII considered more toxic at the earlier stage of AsV exposure should attract sufficient attention to human exposure assessment. Therefore, the pristine As species and exposure duration had significant effects on As bioaccumulation and biotransformation in fish. The behavior determined for dietborne arsenic in food fish is crucial for not only arsenic ecotoxicology but also food safety. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Whilst the hybrids of F1 generations usually experience heterosis for fitness-related traits (including the resistance to parasites), post-F1 generations, due to Dobzhansky–Muller genetic incompatibilities, express numerous disadvantageous traits (including susceptibility to parasites). Genetic disruption in hybrids may also result from the broken system of cyto-nuclear coadaptation. Maternal backcrosses (having parents with the same mtDNA) and paternal backcrosses (having parents with different mtDNA) have the same nuclear genetic compositions, but differ in cytoplasmic genetic elements, affecting their viability and survival. Spring viraemia of the carp virus (SVCV), a disease with a serious economic impact in aquacultures, affects almost exclusively cyprinids, primarily common carp (Cyprinus carpio), and causes high mortality, whilst gibel carp (Carassius gibelio) is a less susceptible species. Our study was focused on the transcriptome profile analysis of head kidney to reveal differential gene expression in highly susceptible common carp, weakly susceptible gibel carp, and hybrid lines, hypothetizing that the patterns of differential gene expression will reflect hybrid heterosis in F1 generations and hybrid breakdown in backcrosses and F2 generations. We expected the differences in differential gene expression between maternal and paternal backcrosses to be in line with the hypothesis of broken cyto-nuclear coadaptation. The pattern of differential gene expression revealed from the transcriptomic analysis of head kidney was linked to the resistance or susceptibility to SVCV infections in two pure species, C. gibelio and C. carpio , and their various generations of inter-specific hybrids. We evidenced hybrid heterosis for F1 generations of hybrids, mostly reflected by similarity in the down-regulation of differentially expressed genes classified within the viral infection disease category. High hybrid breakdown was documented throughout the transcriptomic analysis for paternal backcross generations and F2 generation of hybrids, confirming the broken system of cyto-nuclear coadaptation in those post-F1 generations. This evidence may support the role of intrinsic selection acting against inter-specific hybridization in freshwater fish. • Spring viraemia of carp is a disease with a serious economic impact for aquacultured fish. • We performed transcriptome profile analysis of the head kidney to reveal differential gene expression (DEG) in highly susceptible common carp, weakly susceptible gibel carp, and hybrid lines, hypothesizing that the patterns of differential gene expression reflect heterosis in F1 hybrids and breakdown in backcrosses and F2 hybrids. • DEG was linked to the resistance or susceptibility to SVCV infections in pure species and their various generations of hybrids. • We evidenced the similarity in DEGs between F1 hybrids and weakly susceptible gibel carp supporging hybrid heterosis for F1 hybrids. • Hybrid breakdown was suggested for paternal backcross generations and F2 generation of hybrids, confirming the broken system of cyto-nuclear coadaptation. [ABSTRACT FROM AUTHOR]

Most animals are visually oriented, and their eyes provide their 'window to the world'. Eye size correlates positively with visual performance, because larger eyes can house larger pupils that increase photon catch and contrast discrimination, particularly under dim light, which have positive effects on behaviours that enhance fitness, including predator avoidance and foraging.Recent studies have linked predation risk to selection for larger eyes and pupils, and such changes should be of importance for the majority of teleost fishes as they have a pupil that is fixed in size (eyes lack a pupillary sphincter muscle) and, hence, do not respond to changes in light conditions.Here, we quantify eye and pupil size of individual crucian carp, a common freshwater fish, following controlled manipulations of perceived predation risk (presence/absence). We also tested if crucian carp responded to increased predation risk by shifts in diel activity patterns.We found that crucian carp show phenotypic plasticity with regards to pupil size, but not eye size, as pupil size increased when exposed to predators (pike). Predator‐exposed crucian carp also shifted from diurnal to nocturnal activity. Using a modelling exercise, we moreover show that the plastically enlarged pupils significantly increase visual range, especially for small objects under dim light conditions.Overall, our results provide compelling evidence for predator‐induced pupil enlargement resulting in enhanced visual capabilities in a teleost fish. Pupil size plasticity in combination with the observed shift towards nocturnal activity may allow for efficient foraging also under dark conditions when predation risk from diurnal and visually oriented predators is reduced. The data highlight the powerful role of predation risk for eye development and evolution. [ABSTRACT FROM AUTHOR]

We present a critical checklist of freshwater fish species found so far in the countries of Armenia, Azerbaijan and Georgia. In total 119 freshwater fishes are recorded. There are 40, 86 and 96 species currently known for Armenia, Azerbaijan and Georgia respectively. From these 119 species, seven are endemic and seven species are alien. From the alien species, only three (Carassius gibelio, Gambusia holbrooki and Pseudorasbora parva) can be considered as widespread and invasive. There are four species (Gasterosteus aculeatus, Gobio artvinicus, Perca fluviatilis and Salmo gegarkuni) that are translocated within the region. Seven species are confirmed or recorded for the first time including G. artvinicus and Oxynoemacheilus veyselorum for Armenia, Azerbaijan and Georgia, Capoeta kaput and Rhinogobius lindbergi for Azerbaijan and Georgia, Capoeta razii for Azebaijan, Oxynoemacheilus cemali and Squalius agdamicus for Georgia. In this checklist, Acipenser colchicus is treated as a synonym of Acipenserpersicus. Sand smelts of the Black and Caspian Sea basin are identified as Atherina caspia and Clupeonella caspia is treated as a synonym of Clupeonella cultriventris. Coregonus sevanicus is listed as Coregonus sp. until the situation of Sevan whitefish is better understood. Capoeta sevangi and Capoetaekmekciae are synonyms of Capoetacapoeta. The fish often identified as Capoeta capoeta gracilis from rivers south of the Kura most likely belong to C. razii. The Black and Caspian Sea Rutilus populations are treated as conspecific, therefore R. kutum is a junior synonym of R. frisii. Oxynoemacheilus veyseli is valid as O. veyselorum. We list the alien Rhinogobius species as R. lindbergi, however the name is provisional and needs further confirmation. All Squalius species from the Kura River drainage are identified as S. agdamicus, however in the Aras, it is replaced by S. turcicus. Squalius orientalis is treated as a valid species restricted to the eastern Black Sea basin. The four forms of Lake Sevan trout (Salmo ischchan, S. gegarkuni, S. danilewskii and S. aestivalis) are treated as valid species, two of them (S. ischchan and S. danilewskii) are extinct. Rutilus sojuchbulagi from Azerbaijan is also extinct. [ABSTRACT FROM AUTHOR]

Freshwater fish such as Prussian carp (Carassius gibelio) don't need a feed at a water temperature below 10 °С. To study the rate constants of 137Cs excretion from the body of Prussian carp at different water temperatures (5 and 22 °С) and different feeding, the series of aquarium experiments were conducted. The half-life time of 137Cs activity excretion from fish in the water (T = 5 °С) without feeding (T1/2 = 433 ± 162 days) was 5.6 times higher compared to the rate constants for water temperature 22 °С (T1/2 = 78 ± 4 days) with different types of feeding. The temporal decline of 137Cs activity (Bq) in fish was the same for different feeds, but the activity concentration of 137Cs (Bq-kg-1 ) in fish differed up to 1.8 times (0.0089 ± 0.0005 day-1 and 0.016 ± 0.002 day-1 ) due to different weight gains. [ABSTRACT FROM AUTHOR]

Aeromonas salmonicida is a ubiquitous fish pathogen known to cause furunculosis. With the emergence of new subtypes and the expansion of the host range, it has threatened the health of a variety of marine and freshwater fish, particularly the non-salmonids, manifesting differently from the classical furunculosis. Although there have been reports of infection by atypical strains on the crucian carp, the pathogenesis and tissue pathology remain unclear. In this study, transcriptomics and histopathology were used to analyze the immune response and lesions of crucian carp infected with A. salmonicida. Comparative analysis showed 6579 differentially expressed genes (DEGs) (3428 down-regulated and 3151 up-regulated) were identified on day 5 post-infection (5 dpi). Further annotation and analysis revealed that the DEGs were enriched in enzyme regulator activity, response to oxidative stress, iron ion homeostasis and other functions, and mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), toll-like receptor (TLR), and nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) etc., and immune-related signaling pathways. Meanwhile, the four C-type lysozyme genes found in all DEGs were significantly up-regulated after infection. In addition, there was severe bleeding on the body of the infected fish. Also, the intestine, liver, spleen, and kidney showed varying degrees of inflammatory damage, especially the goblet cell hyperplasia of intestinal mucosa epithelium and degeneration and necrosis of renal tubular epithelium cells. Additionally, with the increase in pathogen concentration, the cumulative mortality increased, the severity of lesions in the hindgut and head-kidney tissues increased. The relative expression levels of four immune-related genes (TNF-α, IL-1β, IL-11, C-lysozyme) were also significantly upregulated, compared with the control (P < 0.05). In conclusion, this study provides a scientific basis for further study on the immune response, pathological diagnosis, and prevention of crucian carp infection caused by atypical A. salmonicida. • A. salmonicida strain did not grow or produce H 2 S at 37 °C. • 6579 differentially expressed genes (DEGs) were identified on day 5 post-infection. • 4 C-type lysozyme genes in all DEGs were significantly up-regulated after infection. • Infected crucian carp had necrosis of renal tubular epithelium cells. • Mortality increased with severity of lesions in hindgut and head-kidney tissues. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the composition of intestinal microflora of freshwater fish in Latvia. A total amount of 28 fish were collected from fishermen (n=20) and retail outlets (n=8), including roach Rutilus rutilus, n=15, crucian carp Carassius carassius, n=5, perch Perca fluvialitis, n=5, bream Blicca bjoerkna, n=3. Microbiological testing consisted of the detection of total viable count (TPC), Enterobacteriaceae and coliforms with subsequent identification with MALDI-TOF Biotyper. TPC, coliforms and Enterobacteriaceae counts ranged from 2.7±0.4 to 5.4±0.3, 2.4±1.5 to 3.7±0.7 and 2.00±1.2 to 3.7±2.5 log cfu/g in gut of wild crucian carp and retailed roach, wild perch and retailed roach, and crucian carp and bream, accordingly. The TPC, coliforms and Enterobacteriaceae counts were significantly higher in retailed fish than in wild fish gut samples (P≤0.05). Gut microbiota were represented by Proteobacteria (93.0%), Firmicutes (3.9%) and Ascomycota (3.1%). The most abundant families were Enterobacteriacea (50.8%) and Pseudomonadaceae (36.7%). Rahnella aquatilis, Serratia fonticola and Pantoe aagglomerans were the most abundant among Enterobacteriaceae while Pseudomonas extremorientalis and P. fragi among the Pseudomonadaceae. Results of the present study show that the gut of freshwater fish were mostly represented by Enterobacteriaceae and Pseudomonadaceae and the presence of fish bacterial pathogens must be considered. [ABSTRACT FROM AUTHOR]

• Biochemical responses of two fish species from two Greek lakes were investigated. • Fish species showed different susceptibility depending on the studied parameters. • Insights into the mechanisms for species acclimation to stressful environments. • The battery of studied biomarkers serves as a tool for lake biomonitoring. Lacustrine ecosystems have been altered by accelerating pollution, excessive nutrient and organic load, water abstraction, and are susceptible to climate change. Hence, suggesting sensitive and reliable biomarkers for early assessments of their status is of urgent need. In this study, two freshwater commercial fish species, Cyprinus carpio (carp) and Carassius gibelio (prussian carp) from two lakes (i.e. Koronia and Volvi, Northern Greece) with different anthropogenic pressures were used and a battery of biochemical and molecular biomarkers related to stress response were analyzed in fish gills and liver. In parallel, water physicochemical parameters (T, DO, pH, conductivity, salinity), BOD 5 and nutrient (N-NO 3 , N-NO 2 , N-NH 4 , P-PO 4) concentrations were measured. Results showed that Lake Koronia had higher conductivity and salinity values and N-NO 2 concentrations. Levels of Heat Shock Response (HSR), MAPK phosphorylation, protein carbonylation, lipid peroxidation products, Bax/Bcl-2 ratio, ubiquitination and caspases were increased in gills and liver of both fish species sampled from Lake Koronia in relation to those of Lake Volvi. Likewise, liver lipid content was increased in both fish species sampled from Lake Koronia compared to those sampled from Lake Volvi. The results indicate and reflect the higher environmental degradation that prevails in Lake Koronia ecosystem in comparison to that of Lake Volvi. The fish species studied showed different susceptibility depending on the biomarkers examined. In addition, our results from both examined species provide insight into the mechanisms involved in acclimatization to stressful environments and support the role of the studied biomarkers as sensitive and reliable tools for ecological assessments of lake ecosystems in biomonitoring studies. [ABSTRACT FROM AUTHOR]

The crucian carp (Carassius carassius, L.) is a cyprinid freshwater species, whose wild‐living populations have decreased in recent years due to an increasing competition of invasive species. Several initiatives were launched, attempting to reintroduce this fish back into its native open waters, which requires the use of crucian carp fry grown under controlled conditions. However, the use of popular commercial diets results in severe developmental abnormalities. The aim of this study was to analyse the impact of feeding natural feed (Chironomidae sp. larvae) or two popular commercial diets on the skeletal development of crucian carp juveniles. Whole‐mount staining and histological methods were used in the study. Skeletal tissues of fish fed both commercial diets were demineralized and displayed a variety of deformities, such as abnormal vertebral spines and vertebral fusion, as well as a new type of deformation, which involved the action of dorsal fin pterygiophores upon the spine. Finally, a novel analytical method was proposed, which utilizes LA‐ICP‐MS for the estimation of bone mineralization. The study proved that basic commercial diets are inadequate for the rearing of crucian carp juveniles. [ABSTRACT FROM AUTHOR]

Considering the economic value of koi carps and the possible direct transmission of the infection in optimal temperature condition, I Dermocystidium i spp. infection should be considered as an important disease also in ornamental species. A new Species of the Genus Dermocystidium, D. koi sp. nov., Parasitic in Cyprinus Carpio L. Nippon Suisan Gakkaishi, 15 (12), 825 - 829. https://doi.org/10.2331/suisan.15.825 Dermocystidium koi found in skin lesions in koi carp (Cyprinus carpio). [Extracted from the article]

To evaluate potential interactive effects of metals and polycyclic aromatic hydrocarbons (PAHs) on biomarker responses, groups of the freshwater fish crucian carp (Carassius auratus) were exposed to single and binary combinations of copper (Cu) (0.01-0.16 mg L-1) with fluorene (Fl) or fluoranthene (Fluo) (2-10 mg kg-1) for 96 h. Dose-dependent increases in the activities of phases I and II metabolic enzymes [7-ethoxyresorufin O-deethylase (EROD) and glutathione-S-transferase (GST), respectively] were observed in fish liver exposed to Fl and Fluo, but these enzyme activities did not differ significantly from the controls when co-treated with higher concentrations of Cu, suggesting an inhibiting interaction on the metabolic enzymes. Although Cu did not alter catalase (CAT) activity, CAT activity was decreased in fish liver exposed to the two PAHs alone or in combination with Cu. Although metallothionein (MT) content in gills was significantly increased following exposure to Cu alone or in combination with Fl and Fluo, the induction folds of MT decreased under co-exposure. Co-exposures to these chemicals invoked complex biomarker responses in fish liver and gills. These results highlight the need for careful consideration of the interactive effects of multiple environmental stressors on fish. [ABSTRACT FROM AUTHOR]

The present study was conducted to determine the effect of stress in liver of Carassius carassius, a freshwater fish that normally dwell in the bottom layer of the waters of lakes, rivers and reservoirs. It is a sedentary fish that naturally feeds on zoo benthos and plant components and thanks to its sensitivity to the changes in surrounding medium is an ideal animal for indication of the health of freshwater aquatic ecosystems. It is susceptible for the teleost fish liver to be disturbed by numerous, stressful factors that influence in their health. Liver pieces of 30 individuals collected from Seferani Lake, in Dumrea region (Elbasan, Albania), were excised and processed for standard histopathological analysis. The result revealed pathological changes in liver tissue including heterogeneity of tissue parenchyma, irregular hepatocyte cells and their nuclei. Massive vacuolization of liver cells and their nuclei, necrotic foci, karyolysis and karyopicnosis were also observed. Our findings imply that histopathological evaluation can be used effectively as biomarker of fish physiological stress response and health status. [ABSTRACT FROM AUTHOR]

Intermuscular bones (IBs) are ubiquitous in most of freshwater farmed fishes, especially in cyprinid species, and the creation of IB-free mutants has become a hot issue in fish genetic breeding because of the potential beneficial for consumers and fish processing industry. Recently, significant progress in the mechanism underlying IB development has been achieved in zebrafish and a decisive player, runt-related transcription factor 2b (runx2b), has been identified. However, its role has not yet been validated in other farmed fishes. Amphitriploid gibel carp (Carassius gibelio) is an important aquaculture species in China, but the injuries threats with approximately 80 IBs have strongly restricted its industry development. In this study, we first identified two homeologs of runx2b (Cgrunx2b-A and Cgrunx2b-B) in gibel carp with about 91.8% identity, each of them possessing three alleles with 99.6% identities. Then, we traced the IB ossification process. Alizarin red S staining showed that gibel carp IB began to ossify at 14 approximately days post hatching (dph) and developed from the posterior to the anterior regions. Cgrunx2b-A and Cgrunx2b-B displayed similar expression pattern but differential expression level during IB development. Moreover, we applied an optimized protocol of CRISPR/Cas9 editing in the polyploid Carassius complex to disrupt the functions of Cg Runx2b-A and Cg Runx2b-B singly or simultaneously. IB development was unaffected by single deficiency of Cg Runx2b-A or Cg Runx2b-B, but simultaneous disruption of all alleles of both Cg Runx2b-A and Cg Runx2b-B leads to complete loss of IB. The results indicate that Cg Runx2b-A and Cg Runx2b-B cooperatively regulate IB development. Importantly, we created several gynogenetic gibel carp mutants, including IB-free Cgrunx2b-A −/−/− ; Cgrunx2b-B −/−/− mutants and IB-less Cgrunx2b-A −/−/− ; Cgrunx2b-B −/−/+ mutants. The current study not only confirms the cooperatively decisive role of two homeologs of runx2b in IB formation, but also provides a feasible gene editing-based approach to create IB-free mutants in gibel carp. • Cgrunx2b-A and Cgrunx2b-B cooperatively regulate intermuscular bone (IB) development in amphitriploid gibel carp. • Single loss of Cg Runx2b-A or Cg Runx2b-B function is unable to affect normal development of intermuscular bones. • Simultaneous disruption of all alleles of both Cg Runx2b-A and Cg Runx2b-B create IB-free gibel carp mutants. [ABSTRACT FROM AUTHOR]

Accumulation of dietary 241Am in freshwater omnivorous fish (Carassius gibelio) was studied aiming to estimate the distribution and retention of 241Am in the fish body. Amphipods labeled with 241Am served as a food item. From 0.4 to 0.6% of ingested 241Am was retained in the fish body after short courses of feeding and depuration, the trophic transfer factor of 241Am for whole organism level was about 2∙10−4. • From 0.4 to 0.6% of ingested 241Am was retained in the fish body. • About 0.1% of ingested 241Am was assimilated in in the fish muscle. • 241Am in liver tended to decrease with the duration of depuration courses. [ABSTRACT FROM AUTHOR]

Blunt snout bream (BSB) is an important economic freshwater fish in China. One of technical bottlenecks in practice lies in improving its hypoxia tolerance. In this study, gynogenesis BSB (GBSB-R) is generated by artificial gynogenesis with UV-inactivated sperms of red crucian carp (RCC), which is regarded as one of freshwater fish with the strongest hypoxia-tolerance. Asynchronous development of the eye pigment further provides an objective morphologic evidence of distinguishing the gynogenesis BSB progeny with the hybrids of BSB (♀) × RCC (♂). It is found that the GBSB-R is a kind of all-female population with normal fertility and its genetic homozygosity is higher than that of wildtype BSB. In view of hypoxia stress tests, physiological indexes and gene expression, the obtained experimental data from this research confirm that the GBSB-R is a new strain with improved hypoxia tolerance, especially compared with the wildtype BSB. These results indicate that artificial gynogenesis is an efficient method to enlarge capacity of the BSB hypoxia tolerance, and the conducted research in this article is valuable to the practical aquaculture. • Gynogenesis blunt snout bream (GBSB-R) generated with UV-inactivated sperms of red crucian carp (RCC) • GBSB-R is a new strain with higher genetic homozygosity and stronger hypoxia tolerance than blunt snout bream (BSB) • An objective evidence to distinguish GBSB-R progeny with hybrids of BSB x RCC by asynchronous development of eye pigments [ABSTRACT FROM AUTHOR]

Blunt snout bream (BSB) is an important economic freshwater fish in China. One of technical bottlenecks in practice lies in improving its hypoxia tolerance. In this study, gynogenesis BSB (GBSB-R) is generated by artificial gynogenesis with UV-inactivated sperms of red crucian carp (RCC), which is regarded as one of freshwater fish with the strongest hypoxia-tolerance. Asynchronous development of the eye pigment further provides an objective morphologic evidence of distinguishing the gynogenesis BSB progeny with the hybrids of BSB (♀) × RCC (♂). It is found that the GBSB-R is a kind of all-female population with normal fertility and its genetic homozygosity is higher than that of wildtype BSB. In view of hypoxia stress tests, physiological indexes and gene expression, the obtained experimental data from this research confirm that the GBSB-R is a new strain with improved hypoxia tolerance, especially compared with the wildtype BSB. These results indicate that artificial gynogenesis is an efficient method to enlarge capacity of the BSB hypoxia tolerance, and the conducted research in this article is valuable to the practical aquaculture. • Gynogenesis blunt snout bream (GBSB-R) generated with UV-inactivated sperms of red crucian carp (RCC) • GBSB-R is a new strain with higher genetic homozygosity and stronger hypoxia tolerance than blunt snout bream (BSB) • An objective evidence to distinguish GBSB-R progeny with hybrids of BSB x RCC by asynchronous development of eye pigments [ABSTRACT FROM AUTHOR]

Oxidative stress and antioxidant responses of crucian carp, upon chronic exposure to endosulfan, were evaluatedin vivo. The lethal concentration (LC50–96 h) was 70 μg L−1; on its basis, the fish were exposed to endosulfan at 20, 35, and 50 μg L−1and autopsy was done on days 1, 2, 3, 4, 7, 14, 21, 28, and 35. Lipid peroxidation was induced in a concentration-dependent manner, being highest at 50 μg L−1(3/4 LC50–96 h, sub-lethal concentration-I, SL-I) on day 4 (720% versus control), followed in its extent (490%) at 30 μg L−1(1/2 LC50–96 h, sub-lethal concentration-II, SL-II) on day 7 and lowest (260%) at 10 μg L−1(1/4 LC50–96 h, sub-lethal concentration-III, SL-III) on day 14. Glutathione showed a concentration- and time-dependent elevation in the initial phase, with highest level on day 4 (180%) at SL-I, but showed significant reduction in all test concentrations from day 21 of post-exposure. Superoxide dismutase was decreased significantly throughout the study, with highest reduction (63%) on day 4 at SL-I; catalase increased in all test concentrations up to day 14 but showed a significant decrease from the day 28 of post-exposure. The potential role of these parameters as indicators of pesticide pollution in aquatic systems is discussed. [ABSTRACT FROM PUBLISHER]

Highlights: [•] ROX in water could accumulate in crucian carp, particularly in liver and bile. [•] Seventeen metabolites were detected in bile. [•] A plausible scheme for biotransformation pathways of ROX in fish was depicted. [•] ROX could induce change of biomarkers, which related to ROX or its metabolites. [ABSTRACT FROM AUTHOR]

Zhao, H.-Y., Zhang, G.-H., Bai, L., Zhu, S., Shan, Q., Zeng, D.-P., Sun Y.-X. Pharmacokinetics of florfenicol in crucian carp ( Carassius auratus cuvieri) after a single intramuscular or oral administration. J. vet. Pharmacol. Therap. 34, 460-463. The pharmacokinetics of florfenicol (FF) was studied in plasma after a single dose (40 mg/kg) of intramuscular (i.m.) or oral gavage (p.o.) administration to crucian carp ( Carassius auratus cuvieri) in freshwater at 25 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two-compartment open models follow both routes of administration. The estimates of total body clearance (CLb), volume of distribution ( Vd/ F), and absorption half-life ( T1/2(ka)) were 0.067 L/h/kg and 0.145 L/h/kg, 2.21 L/kg and 1.04 L/kg, 2.75 and 1.54/h following i.m. and p.o. administration, respectively. After i.m. injection, the elimination half-life ( T1/2(β)) was calculated to be 38.2h, the maximum plasma concentration ( Cmax) to be 16.82 μg/mL, the time to peak plasma FF concentration ( Tmax) to be 1.50 h, and the area under the plasma concentration-time curve (AUC) to be 597.4 μg/mL·h. Following p.o. administration, the corresponding estimates were 2.17 h, 29.32 μg/mL, 1.61 h, and 276.1 μg/mL·h. [ABSTRACT FROM AUTHOR]

Summary The identification of fish species from head bone remains is employed in various sciences, including archaeology, paleontology and field ecology, with the estimation of fish size from biometric relationships being useful in the assessment of predation pressure exerted by increasing numbers of piscivorous species (e.g. Eurasian otter Lutra lutra and great cormorant Phalacrocorax carbo). This is particularly relevant for crucian carp, Carassius carassius, which is in decline in Europe due to changes in land use and to increasing numbers of non-native Carassius species (i.e. goldfish C. auratus, gibel carp C. gibelio), which hybridize with C. carassius. However, diagnostic keys and biometric relationships are lacking for C. carassius and its most common hybrids, crosses with C. auratus. The present paper addresses this gap in knowledge, providing diagnostic keys and biometric relationships for the head bones of all Carassius species found in Europe as well as for C. carassius × C. auratus hybrids. All bone size to body length relationships were statistically significant. Similarly, all bone size to body weight relationships were significant for C. carassius, C. auratus, and C. gibelio, but none were significant for C. carassius × C. auratus hybrids. Diagnostic structures were found to distinguish easily between the Carassius species and hybrids, which will assist in determining the identity and sizes of prey found in faecal and archaeological remains. [ABSTRACT FROM AUTHOR]

Abstract: In general, copper is primarily an osmoregulatory toxicant to fish and Cu toxicity is thought to be related to the rate of sodium loss. Looking at a previous research it is striking that gibel carp, Carassius auratus gibelio, do not seem so susceptible to the first ionoregulatory shock phase of Cu exposure, but rather build up physiological disturbances slowly until mortality occurs. Since it was noted that gibel carp experience severe hypoxia under Cu exposure, we hypothesised that, besides the Na loss, the slow depletion of liver glycogen stores contributed equally to the collapse of physiological integrity. It is clear from our results that glycogen stores are being depleted in Cu exposed fish and that dead fish suffered more extensive glycogen losses compared to surviving fish, with liver glycogen levels of 125±8mg g− 1 in dead fish compared to 230±13mg g− 1 in surviving fish. However, changes in liver glycogen did not contribute significantly to mortality, while changes in whole body sodium and the rate of sodium loss did. Whole body Na levels dropped from 1111±48μg g− 1 dry weight in control fish to 850±54μg g− 1 in surviving fish and to 607±24μg g−1 in fish that had died resulting in Na loss rates of 1.25±0.22μg g−1 h−1 and 3.39±0.19μg g−1 h−1 in surviving and dead fish respectively. Our results support the finding that the rate of Na loss largely determines Cu toxicity in fish, even in resistant species. [Copyright &y& Elsevier]

Abstract: Crucian carp (Carassius carassius) were exposed to a Cu rich medium (pH 6.6, conductivity 25 μS/cm, 2.91 mg Ca2+/l, approximately 300 μg Cu2+/l). Untreated department water (pH 6.6, conductivity 25 μS/cm, 2.91 mg Ca2+/l) acted as control. Mortality in crucian carp was first observed after 13 days of exposure to the Cu rich medium. There were, however, significant changes in haematocrit, plasma chloride, plasma sodium and water content in muscle in fish exposed to the Cu rich medium after two days. After 14 days of exposure to copper, haematocrit increased to 52±2% (control: between 37 and 40%), plasma chloride decreased to 45±5 mmol/l (control: 99–106 mmol/l), plasma sodium decreased to 81±6 mmol/l (control: 116–137 mmol/l), and water content in muscle increased to 83.0±0.3% (control: 78.7–79.9%). No apparent changes in blood ethanol, and minor changes in plasma lactate were observed in copper exposed fish. Analyses of the gills revealed an increasing concentration of copper on the gills from fish exposed to Cu rich water. After 14 days, the concentration of copper accumulated in the gill was 12.8±4.1 μg Cu/g wet weight (control: 0.91–1.19 μg Cu/g wet weight). A reduction of the respiratory area in fish exposed to copper was observed, in terms of both lamellar and filamental fusion. The normoxic O2 uptake did not change, but the critical oxygen tension was elevated to 6.12±1.04 mg O2/l after a 6 day exposure to copper (control: 1.03±0.05 mg O2/l). This study shows that crucian carp has a higher tolerance to copper compared to other freshwater fish species. Our results suggest that this tolerance is based on the ability of crucian carp to avoid becoming hypoxic as well as an extreme tolerance to severe loss of plasma ions. [Copyright &y& Elsevier]

This paper presents 145 length–weight relationships gathered from the literature pertaining to 30 Turkish freshwater fish species belonging to six families. The value of the slope b ranged from 2.04 for Carassius carassius to 3.46 for Scardinus erythroptalmus. The mean value of b was 2.91 (SD = 0.305), which did not differ significantly from 3.0 ( t-test, P > 0.05). The median value of b was 2.95; 50% of the b values ranged from 2.68 to 3.14. The plot of log a vs b was used to detect outliers. [ABSTRACT FROM AUTHOR]

Abstract: Polychlorinated biphenyls (PCBs) levels in crucian carp were determined at 20 locations along four major river systems, several small-scale rivers and a wetland in Korea. Twenty-eight congeners, ranging from tri- to hepta-CBs were detected. A gas chromatograph with a mass selective detector was used to quantify the individual PCB congeners. The objectives of this study were to investigate the levels of contamination of PCBs in freshwater fish and to observe the pattern of their distribution. The sampling locations were chosen among 31 sampling sites that are currently used as environmental residue checkpoints by the Korean Ministry of Environment. Concentrations of individual congeners ranged from not detectable (n.d.) to 0.75ngg−1 on a wet weight basis. The total concentrations of PCBs at each site ranged from n.d. to 5.41ngg−1 of wet weight. The most heavily contaminated site was the Nakdong estuary located near the Shinpyung-Janglim factory district. The PCB 153 and 138 were the principal congeners and penta- and hexa-chlorinated biphenyls comprised the main congener groups. [Copyright &y& Elsevier]

Vøllestad LA, Varreng K, Poléo ABS. Body depth variation in crucian carp Carassius carassius: an experimental individual-based study. Ecology of Freshwater Fish 2004: 13: 197–202. © Blackwell Munksgaard, 2004 Induced morphological defences, where individuals develop morphological structures as a response to signals from sympatric predators, are common among invertebrates. Such defences have also been reported in a freshwater fish, the crucian carp Carassius carassius. In crucian carp, the presence of piscivorous fish presumably induces the development of a deep body as a defence mechanism. We tested how the growth rate (in body depth, length and mass) of individually tagged crucian carp responds to pike Esox lucius odours and control water. In general, crucian carp exposed to pike odour grew better (both in length and mass) than control fish. The treatment crucian carp also developed deeper bodies than control crucian carp. Further, there was a strong positive relationship between individual growth rate and the rate of change in body depth and this relationship did not differ between control and treatment fish. [ABSTRACT FROM AUTHOR]

Citrobacter freundii , a common pathogen of freshwater fish, severely restricts the sustainable development of the aquaculture industry. In this study, the novel C. freundii strain CFC202 was isolated from the intestines of crucian carp, which was annotated with three virulence factors related to promoting bacterial colonization and causing anemia by the whole genome analysis. We found that the strain adhered to the surface of hepatic L8824 cells, and actin aggregation occurred at the adhesion site of the strain. Then, C. freundii was fluorescently labelled and imaged the distribution of crucian carp under an In Vivo Imaging System (IVIS) during natural infection. The results showed that this strain mainly gathered in the intestines of crucian carp, and the intestinal villi were severely damaged by TEM. From the results of histopathological examination, the intestinal mucosa was obviously shed and various organs were damaged. Hence, we speculated that C. freundii could cause attaching and effacing (A/E) lesions to fish cells, which in turn caused pathological changes to various organs. Moreover, we constructed C. freundii ghost (CFG) and evaluated their immune effects by oral and injection immunization in crucian carp. Compared with the non-immunized group, non-specific immune indicators (ACP, AKP, SOD, and LZM), agglutination antibody titres of the serum, and the expression of immune-related genes (TNF-α and IL-6) of the head kidney and spleen were significantly increased in the immunized group (P < 0.01), indicating that innate and specific immune responses were induced by the CFG. In addition, the immunized fish showed higher protection than the non-immunized fish after challenge: oral control (20.00% survival); oral test (80.21% survival); injected control (6.67% survival); injected test (87.50% survival). Taken together, our research was the first to demonstrate that the constructed CFG might be developed as either oral or injected vaccines against C. freundii in aquaculture. • Citrobacter freundii CFC202 was firstly isolated from the diseased crucian carp in the Dongting Lake area of China. • Genome analysis of CFC202 showed it could mediate adhesion to cell surface through virulence factors such as hop AJ2 and fep E. • Strain CFC202 could cause attaching and effacing lesions to fish cells in vivo and in vitro. • This study was the first to construct Citrobacter freundii ghost and evaluate their immune effects in crucian carp. • Immunization with CFG vaccine in advance in crucian carp could improve disease resistance against Citrobacter freundii. [ABSTRACT FROM AUTHOR]

Allotetraploids play central roles in the field of polyploid breeding of freshwater fishes. The molecular basis underlying distant hybridization and individual differences between allotetraploids and their parents is largely unknown. In this study, we performed quantitative proteomics profiling in gonad and liver tissues between allotetraploid and its parents Red Crucian Carp (♀) and Common Carp (♂) respectively. Thousands of proteins were identified and quantified. Species and tissue specific analysis revealed that a large number of causal proteins are specifically regulated in gonad or liver tissue in allotetraploid and its parents respectively. Subsequently, integrative bioinformatics analyses including functional enrichment, pathway and network analyses were conducted. The results suggested a series of gonad and liver specifically regulated proteins such as LSM3, LSM7, PABPC1B and ALDH3A1, EHHADHB, ACAT2 play crucial roles in reproduction-related and metabolism-related pathways including "DNA replication", "Spliceosome" and "Metabolic pathways", "Biosynthesis of antibiotics". Meanwhile, species specifically regulated proteins such as FMR1, MAO are involved in "RNA transport", "Glycine, serine and threonine metabolism". Herein, we established the first comprehensive proteomics knowledgebase for particular freshwater fishes. It may shed light on the molecular mechanisms underlying polyploidy breeding and individual differences and serve as an indispensable reference for further studies. The molecular basis underlying distant hybridization and individual differences between allotetraploid and their parents Red Crucian Carp and Common Carp is largely unknown. Quantitative proteomics profiling integrated with multiple bioinformatics analysis revealed that a large number of causal proteins are specifically expressed in gonad or liver tissue in allotetraploid and its parents. Herein, we established the first comprehensive proteomics knowledgebase for particular freshwater fishes. It may shed light on the molecular mechanisms underlying polyploidy breeding and individual differences and serve as an indispensable reference for further associated studies. Unlabelled Image • Quantitative proteomic profiling was conducted based on two tissues among three species. • Multiple bioinformatics analysis were performed based on species and tissue specifically expressed proteins. • The first comprehensive proteomics knowledgebase for particular freshwater fishes was established. [ABSTRACT FROM AUTHOR]

The Japanese archipelago is located at the periphery of the continent of Asia. Rivers in the Japanese archipelago, separated from the continent of Asia by about 17 Ma, have experienced an intermittent exchange of freshwater fish taxa through a narrow land bridge generated by lowered sea level. As the Korean Peninsula and Japanese archipelago were not covered by an ice sheet during glacial periods, phylogeographical analyses in this region can trace the history of biota that were, for a long time, beyond the last glacial maximum. In this study, we analyzed the phylogeography of four freshwater fish taxa, Hemibarbus longirostris, dark chub Nipponocypris temminckii, Tanakia ssp. and Carassius ssp., whose distributions include both the Korean Peninsula and Western Japan. We found for each taxon that a small component of diverse Korean clades of freshwater fishes migrated in waves into the Japanese archipelago to form the current phylogeographic structure of biota. The replacements of indigenous populations by succeeding migrants may have also influenced the phylogeography. [ABSTRACT FROM AUTHOR]

• Parallel conversion between arsenite and arsenate occurred in freshwater fish. • The arsenic dimethylation activity induced oxidative damage. • Acclimated physiology occurred after dietborne arsenic exposure to resist toxicity. • Arsenobetaine became predominant in freshwater fish after dietborne arsenic exposure. The metabolic process and toxicity mechanism of dietary inorganic arsenic (iAs) in freshwater fish remain unclear to date. The present study conducted two iAs [arsenate (As(V)) and arsenite (As(III))] dietary exposures in freshwater fish crucian carp (Carassius auratus). The fish were fed on As supplemented artificial diets at nominal concentrations of 50 and 100 μg As(III) or As(V) g−1 (dry weight) for 10 d and 20 d. We found that the liver, kidney, spleen, and intestine of fish accumulated more As in As(V) feeding group than that in As(III), while the total As levels in muscle were similar between As(V) and As(III) group at the end of exposure. Reduction of As(V) to As(III) and oxidation of As(III) to As(V) occurred in fish fed with As(V) and As(III), respectively, indicating that toxicity of iAs was likely elevated or reduced when iAs was absorbed by fish before entering into human body through diet. Biomethylation to monomethylarsonic acid and dimethylarsinic acid and transformation to arsenocholine and arsenobetaine were also found in the fish. The linear regression analysis showed a positive correlation between secondary methylation index and the malondialdehyde content in tissues, highlighting the vital role of arsenic dimethylation in the oxidative damages in fish. [ABSTRACT FROM AUTHOR]

• TiO 2 NPs effects on terrestrial and aquatic animal models were examined. • Oxidative, proteolytic, genotoxic and apoptotic parameters increased due to TiO 2 NPs. • NPs caused a significant reduction in swimming capacity of zebrafish. • The studied parameters are suggested as biomarkers in biomonitoring studies. • The activation of similar responses implies the existence of a conserved mechanism. Titanium dioxide nanoparticles (TiO 2 -NPs) are among the most popular manufactured and widely used nanoparticles. They are released into the environment, affecting terrestrial and aquatic ecosystems, with unexpected consequences to organisms and human health. The present study investigates the mediated toxicity imposed to the freshwater fish species, zebrafish (Danio rerio) and the prussian carp (Carassius gibelio), and to the terrestrial land snail Cornu aspersum , after their exposure to sublethal concentrations of TiO 2 -NPs. Oxidative, proteolytic, genotoxic and apoptotic parameters in fish liver and gills, as well as on snail hemocytes were studied and the swimming performance was estimated in order to (a) estimate and suggest the most susceptible animal, and (b) propose a common battery of biomarkers as the most suitable indicator for biomonitoring studies against TiO 2 -NPs. Our in vivo experiments demonstrated that NPs induced detrimental effects on animal physiology and swimming behavior, while no general pattern was observed in species and tissues responsiveness. Generally, TiO 2 -NPs seemed to activate a group of molecules that are common for aquatic as well as terrestrial animals, implying the existence of a conserved mechanism. It seems that after exposure to TiO 2 -NPs, a common mechanism is activated that involves the stimulation of immune system with the production of ROS, damage of lysosomal membrane, protein carbonylation, lipid peroxidation, DNA damage, following proteolysis by ubiquitin and finally apoptosis. Thus, the simultaneous use of the latter biomarkers could be suggested as a reliable multi parameter approach for biomonitoring of aquatic and terrestrial ecosystems against TiO 2 -NPs. [ABSTRACT FROM AUTHOR]

Different kinds of freshwater fish soups show a diverse range of health functions, due to their different nutritional substances and corresponding bioactivities. In the current study, in order to learn the theoretical basis of the potential role fish soup plays in diet therapy functions, the changes of nutrient profiles and antioxidant activities in crucian carp soup and snakehead soup (before and after simulated gastrointestinal digestion) were investigated, such as chemical composition, free amino acids, mineral and fatty acid contents, DPPH radical scavenging activity, ferrous ion chelating activity, hydroxyl radical-scavenging activity and the reducing power effect. Results show that the content of mineral elements in snakehead fish soup was significantly higher than that of crucian carp soup, especially for the contents of Ca, Zn, Fe. The content of total amino acid (TAA) of crucian carp soup (82.51 mg/100 mL) was much higher than that of snakehead fish soup (47.54 mg/100 mL) (p < 0.05). Furthermore, the antioxidant capacity of crucian carp soup was stronger than that of snakehead soup. The intensive profiles of nutritional composition and antioxidant activities of these two kinds of fish soups were expected to partly provide the theoretical basis of therapeutic effects. [ABSTRACT FROM AUTHOR]