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The release of hatchery-reared fish fry for restocking is important for the enrichment of fishery resources; however, the effective evaluation of the success rate of marking such fish is challenging. We exposed juvenile crucian carp (Carassius carassius) to a single concentration of SrCl2·6H2O for 5 d and evaluated the efficiency of Sr marking of the fish otoliths (sagittae, asterisci, and lapilli) using an electron probe micro-analyzer. Sr marking signatures formed a peak in all otolith types, with a marking success rate of 100%. The ratio of Sr to Ca in the lapilli and sagittae was higher than that in the asterisci. It took 2 d from the beginning of immersion to the deposition of Sr on the lapilli and sagittae, and the time delay for asterisci was 1 d. For the lapilli and sagittae, it took 16 d to terminate Sr marking and fully recover to the pre-marking Sr level, whereas it was 12 d for the asterisci. The application of the Sr dose had no effect on the survival or growth of the carp. This study demonstrated that the lapilli are the most suitable otolith type for Sr marking observations in crucian carp and provides a theoretical basis and technical support for carp restocking using the Sr marking approach. [ABSTRACT FROM AUTHOR]

Activity concentrations of 90Sr in fish in lakes located within the Chornobyl Exclusion Zone (ChEZ) reach 100 kBq kg−1, which is several thousand times higher than the permissible level in Ukraine (35 Bq kg−1). This study was conducted in the natural conditions of the ChEZ to determine the effectiveness of keeping radioactively contaminated fish in "clean" water to reduce the 90Sr content of their muscle tissue, as previously shown in short-term laboratory experiments. It was found that transferring tench (Tinca tinca (Linnaeus, 1758)) from Lake Glubokoye one of the most contaminated lakes in the ChEZ, to a cage in the "clean" Lake Starukha for 45 days did not lead to a significant decrease in 90Sr content in both bone and muscle tissues. Establishing permissible levels of 90Sr concentration only in fish fillet, and not in the whole fish body (with bone tissue), is appropriate for human radiation protection, since the retention factors of 90Sr treatment for boiled bone tissue of crucian carp from the Chornobyl exclusion zone are less than 0.01, and up to 97% of strontium is contained in bone tissue. [Display omitted] • No reduce of 90Sr content in contaminated fish when kept in "clean" water for 45 days. • Less than 1% of 90Sr is transferred to broth during boiling of fish bone tissue. • Current Ukrainian permissible levels of 90Sr in fish products need to be revised. • Long-term experiments are needed to study ways to remove 90Sr from fish tissues. [ABSTRACT FROM AUTHOR]

Fish in lakes situated within the Chornobyl exclusion zone have been highly contaminated since the accident and have not been utilized as food for humans. In the present study, field experiments with less-contaminated silver Prussian carp (Carassius gibelio (Bloch, 1782)) caged in contaminated lake within the Chornobyl exclusion zone was performed from June to October 2021 to investigate the effectiveness of clean feed containing potassium ferric hexacyanoferrate (KFCF) KFe[Fe(CN) 6 ], a kind of Prussian Blue as a countermeasure to reduce 137Cs accumulation in fish. The addition of clean feed containing 0.1% or 1% KFCF resulted respectively in 2.4 ± 0.4 or 4.2 ± 0.7 times lower activity concentration of 137Cs in muscle tissue of the carp compared to control fish with clean feed without KFCF and in 7–16 or 12–27 times lower activities compared to fish without additional clean feeding. After 18 weeks exposure, 137Cs levels in all the caged fish except for the control group were below the European permissible level (600 Bq kg−1) for consumption. In contrast, KFCF did not affect the intake of 90Sr in fish, although additional feed increased the growth rate and thereby accumulation in bone tissues. Hence, the use of clean feed containing KFCF is judged to be an effective and inexpensive countermeasure to reduce the 137Cs contamination of edible fish muscles. [Display omitted] • The reduction factor of 137Cs ranged from 7 to 27 for fish given clean feed containing potassium ferric hexacyanoferrate (KFCF). • Application of clean feed decreased the 137Cs activity concentration in muscle only by a factor of 2.6 ± 0.3 during summer. • Application of clean KFCF diet affected neither the intake of 90Sr in fish nor fish growth. • Field experiments are needed to identify efficient countermeasures for fish. [ABSTRACT FROM AUTHOR]

This is the first large dataset of underwater videos from which species occurrence and behavioral records of aquatic organisms were identified in Lake Biwa, the largest lake in Japan. We compiled 109 videos and 122 still‐images of fishes, diving birds and shrimps. The images were cropped from videos taken underwater with animal‐borne video cameras which were mounted on the backs of common carp (Cyprinus carpio). The attribute of each image and its occurrence of organisms were formatted according to the Darwin Core Archive which was developed by the Biodiversity Information Standards (TDWG), and the dataset is available via the Global Biodiversity Information Facility. Our dataset includes records of 10 species, 4 genera, 2 families and 1 infraorder which includes mostly fishes, several birds and a crustacean. The fish records include a threatened endemic fish, the "gengorou‐buna" crucian carp (Carassius cuvieri), and two alien fishes, largemouth bass (Micropterus salmoides) and bluegill sunfish (Lepomis macrochirus). We confirmed several types of intraspecific and interspecific relationships between video‐mounted carp and other organisms; for example, most video‐mounted carp frequently approached or chased conspecifics upon encountering, which sometimes led to two carp feeding side by side. At least three avian species also appeared in the dataset: Eurasian coot (Fulica atra), little grebe (Tachybaptus ruficollis), great crested grebe (Podiceps cristatus), but there was no apparent interaction between carp and these birds. Our underwater videos reveal and highlight the rich biodiversity of the lake today, providing clear evidence for behavior of aquatic organisms under natural conditions. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2020-18.1/jalter-en. [ABSTRACT FROM AUTHOR]

The article touches upon the morphological characteristics of Crucian carp Carassius gibelio (Bloch, 1782), Kura chub Alburnoides eichwaldii, Kura nase Chondrostoma cyri, Stone moroko Pseudorasbora parva, Grass carp Ctenopharyngodon idella currently found in the Karnut Reservoir, as well as the extensity and intensity of infection of individual fish species such as Ligula intestinalis with plerocercoid. Based on the conducted studies, it is recommended to increas the fish productivity of the Karnut Reservoir by importing and breeding the most economically valuable fish species, thus contributing to the socio-economic sustainable development of rural communities. [ABSTRACT FROM AUTHOR]

Tactile reception in cyprinid fish (silver crucian carp Carassius auratus gibelio and common carp Cyprinus carpio) was investigated by noninvasive recording of action potentials from the head skin in response to rhythmic tactile stimulation. Responses shaped as electric potentials following synchronously with changes in the pressure force on the skin were recorded using chloro-silver electrodes. It was shown that fish, like all terrestrial vertebrates, have phasic and tonic tactile receptors. Three main types of tactile responses were distinguished: (1) tonic responses as potential fluctuations repeating the dynamics of the tactile stimulus, (2) phasic responses as on-, off-, and on-off potentials, and (3) slow deflections from the resting potential. Compound responses comprising simultaneously different types of responses were also recorded. The response latency averaging 6.1 ms for tonic and 4.4 ms for phasic responses was clearly independent of the stimulus direction (switch-on, switch-off). The threshold level of tactile sensitivity in the perioral and gular head areas was 0.05–0.2 g/mm2. Tactile receptors on the silver crucian carp and common carp heads exhibited zonal distribution patterns, with sensory areas differing in their tactile sensitivity. Most sensitive areas were on the upper and lower lips, in the perilabial skin and the gular area on the ventral side of the head. Less sensitive areas were situated rostrally and ventrally to the eyeball. The areas situated dorsally and caudally to the eyeball proved to be insensitive to the applied tactile stimulation. In all sensory areas on the fish head, most intense responses were evoked by sliding tactile stimuli. The distribution specificity of tactile sensory areas meets their functional significance for fish feeding behavior. [ABSTRACT FROM AUTHOR]

Sakarya River with a length of 824 km is one of the most important lothic ecosystems of Turkey. Sarıyar, Gökçekaya and Yenice Dams were constructed on the Sararya River for the purpose of electric supply and utility water for agricultural and fishery activities. In this study, sediment samples were collected from 14 stations selected on areas seasonally (2015–2016). Also, cyprinidae species (Carassius gibelio (Bloch, 1782), Capoeta baliki Turan, Kottelat, Ekmekçi & Imamoglu 2006) were caught from Dam Lakes and Sakarya River. Cr, Ni, Cu, Zn, Pb levels in sediment samples and in tissues (liver, gill and muscle) of fish were analyzed in samples by Analytic Jena ContrAA 700 (high-resolution continuum source atomic absorption spectrometer). The data observed were evaluated with national and international quality criteria. According to the data in the study results, heavy metal accumulations in the gill and liver of fish were determined higher than muscle. Zn levels in muscle of C. gibelio caught from Yenice Dam Lake were higher than the permissible limit stated by Turkish legislation and FAO. Also, Cr and Ni levels in sediment samples especially during rainy seasons were higher to dry seasons and Cr and Ni levels were detected higher than sediment quality guidelines. [ABSTRACT FROM AUTHOR]

Contracaecum rudolphii (s. l.) is a complex of sibling species of anisakid nematodes having the fish-eating birds belonging to the Family Phalacrocoracidae as final hosts. The great cormorant Phalacrocorax carbo sinensis is parasitized by C. rudolphii A and C. rudolphii B. Adults and L4 specimens of C. rudolphii (s. l.) (N = 3282) were collected in cormorants from brackish and freshwater ecosystems of Central Italy. Third-stage larvae of Contracaecum (N = 882) were obtained from the fish species Dicentrarchus labrax, Anguilla anguilla, Aphanius fasciatus, Atherina boyeri, Leuciscus cephalus, Barbus barbus, and Carassius carassius captured in the same geographical areas of cormorants' standings. Contracaecum rudolphii A and C. rudolphii B were identified by a multilocus genetic approach: allozymes, sequences analysis of the mtDNA cox2, and ITS region of rDNA gene loci. Differential distribution of the two parasite species was observed in different aquatic environments. Contracaecum rudolphii B outnumbered C. rudolphii A in wintering cormorants from freshwater ecosystems; the opposite trend was found in cormorants from brackish water. Analogously, C. rudolphii A larvae were more prevalent in brackish water fish, while C. rudolphii B larvae were found infecting only freshwater fish. The findings seem to confirm that C. rudolphii A and C. rudolphii B would have a life-cycle adapted to brackish and freshwater environments, respectively. A differential feeding behavior of wintering cormorants, the ecology of the infected fish species, and abiotic factors related to early stages of the parasites are supposed to maintain the distinctiveness of the two parasite species' life cycles in the two different aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The Ichthyofauna of Joghaz reservoir in Tavush region has been studied for the first time, where 7 species have been identified: Crucian carp, Common carp, Scrapper, Kura bleak, Stone moroko, Golden spined loach registered in RA Red Book of Animals and unidentified type Cobitis. The most numerous types of these species are Crucian carp, Scrapper, Kura bleak and Stone moroko, which, by their external characteristics, are not substantially different from the same species of fish found in the other freshwaters of Armenia. [ABSTRACT FROM AUTHOR]

Light is one of the most important environmental factors that influence many physiological, biochemical and behavioral reactions of aquatic organisms. In this work, experiments were conducted to study how illumination influences on the growth of juveniles of two carp fish species (Carassius gibelio and Carassius carassius). In this work, experiments. The experiments were carried out in aquariums and trays with a light gradient. Twenty-twenty five fish were placed in each aquarium, three-four individuals were placed in trays. Fish were fed to saturation three times a day. Optimal types of illumination were identified for the growth of both species. 200-930 lx is optimal for juvenile Carassius gibelio. 230-500 lx is optimal for juvenile Carassius carassius. High illumination and total darkness negatively influenced the growth of both species. Very high illumination considerably slowed the growth rate. Survival in all cases was at 100%. Motor activity of juvenile Carassius gibelio in light-gradient conditions was higher than in balancing illumination. The number of vector movements, the average distance of movement and the total path of fish in the light gradient exceed the corresponding values in control in balancing illumination. When there was no food, the elected zones of the juvenile Carassius gibelio were shifted toward higher illumination. When the food was absent for half an hour, the juveniles chose a zone with the illumination of 600 lux (total time of stay was 15.8 minutes for 1 h). When it was absent for two hours, the juveniles chose a zone with the illumination of 1000 lux (17.3 minutes), and when it was absent for 24 hours, juveniles chose a zone with the illumination of 1000-1200 lux (28.5 minutes). The study discusses the effect of light on growth, the behavior of two species of fish. [ABSTRACT FROM AUTHOR]

In mammals and fish, emerging evidence highlights that TRIM family members play important roles in the interferon (IFN) antiviral immune response. Fish TRIM family has undergone an unprecedented expansion leading to generation of finTRIM subfamily, which is exclusively specific to fish. Our recent results have shown that FTRCA1 (finTRIM C. auratus 1) is likely a fish species-specific finTRIM member in crucian carp C. auratus and acts as a negative modulator to downregulate fish IFN response by autophage-lysosomal degradation of protein kinase TBK1. In the present study, we found that FTRCA1 also impedes the activation of crucian carp IFN promoter by IRF7 but not by IRF3. Mechanistically, FTRCA1 attenuates IRF7 transcription levels likely due to enhanced decay of IRF7 mRNA, leading to reduced IRF7 protein levels and subsequently reduced fish IFN expression. E3 ligase activity is required for FTRCA1 to negatively regulate IRF7-mediated IFN response, because ligase-inactive mutants and the RING-deleted mutant of FTRCA1 lose the ability to block the activation of crucian carp IFN promoter by IRF7. These results together indicate that FTRCA1 is a multifaceted modulator to target different signaling factors for shaping fish IFN response in crucian carp. • FTRCA1 impedes the activation of crucian carp IFN promoter by IRF7. • FTRCA1 attenuates IRF7 transcription levels likely due to enhanced decay of IRF7 mRNA. • E3 ligase activity is required for FTRCA1 to negatively regulate IRF7-mediated IFN response. [ABSTRACT FROM AUTHOR]

Abstract Intestinal bacteria play an important role in the health and provide a variety of beneficial effects to host. Immunosuppressant can reduce the immunity of host and increase the susceptibility to pathogens. But it is not clear whether the increased susceptibility caused by immunosuppressant is related to changes of gut microbiota. In this study, we used crucian carp administrated with dexamethasone to explore the effects of immunosuppressants on gut microbial communities and further evaluate the potential association between changes in gut microbiota and susceptibility to pathogens. The results of MANOVA based on the top 10 PCoA axis scores from unweighed/weighted UniFrac distances showed that administration of dexamethasone (P = 0.021) and the administration time (P = 0.027) had a significant impact on the gut microbial composition, regardless of pathogens infection status (P = 0.35). After administration with dexamethasone, the fish had higher abundance of Cetobacterium and lower abundance of Bacillus and Lactococcus , and the abundance of genus Bacillus, Pseudomonas and Lactococcus decreased along with prolong administration time of dexamethasone. The results may help us understand the correlation between the host susceptibility to pathogenic bacteria and gut microbial community shift, and extend our knowledge regarding the role of gut microbiota in keeping the balance between pathogenic and symbiotic bacteria. Highlights • Administration of dexamethasone had a significant impact on the gut microbial composition. • Fish had higher level of Cetobacterium and lower Bacillus and Lactococcus genus after injected with dexamethasone. • The level of genus Bacillus , Pseudomonas and Lactococcus decreased along with prolong administration time of dexamethasone. [ABSTRACT FROM AUTHOR]

Abstract The crucian carp (Carassius auratus) and common carp (Cyprinus carpio) are close relatives and coexist in most of their natural habitats but with different levels of abundance. The crucian carp is usually more abundant than the common carp in high predation-pressure habitats. To verify whether the crucian carp exhibits a significantly higher survival capacity combined with additional antipredator strategies than the common carp, we measured the morphology, behavioral traits, fast-start escape swimming performance and survival time under predation in both fish species. Additionally, the relationships between morphology, behavioral traits, locomotion and survival in both fish species were analyzed to determine which components can explain survival. We found that the crucian carp showed significantly higher survival times combined with greater body depth and fast-start escape performance than did the common carp, and the fast-start escape performance may be the main reason that the crucian carp showed a higher survival capacity. Additionally, the predator (Channa argus) chased the common carp more frequently when exposed to both species simultaneously. The higher survival capacity of the crucian carp and the preference of the predator for the common carp may be partial reasons that crucian carp were more abundant in habitats with high-predation pressure. Despite the differences among species, only the fast-start maximum velocity and exploration of the crucian carp were significantly related to survival time based on Pearson correlations. Overall, the relationships between the components measured in this study and survival in both fish species were quite weak or even lacking, which may be associated with the lack of predation experience in the fish specimens used. Highlights • We examined why the proportions of two closely related fish species are different abundant in high-predation habitats. • The more abundant fish have larger body depth, stronger fast-start escape performance and greater survival than the less abundant fish. [ABSTRACT FROM AUTHOR]

In mammals, tripartite motif (TRIM) proteins have emerged as pivotal players endowed with, directly, antiviral effects and, indirectly, modulatory capacity of the innate immune response. An unprecedented expansion of TRIM family has occurred in fish; however, the functional role of fish TRIM family members remains largely unknown. In this study, we identify a species-specific TRIM gene from crucian carp Carassius auratus, named FTRCA1, phylogenetically similar to the members of finTRIM, a subfamily of TRIM exclusively in teleost fish. FTRCA1 is induced by IFN and IFN stimuli as a typical IFN-stimulated gene. Overexpression of FTRCA1 negatively regulates IFN antiviral response by inhibition of IRF3 phosphorylation; consistently, knockdown of FTRCA1 results in enhanced levels of IRF3 phosphorylation and also IFN expression following poly(I:C) transfection. Whereas FTRCA1 is associated with several pivotal signaling molecules of RIG-I--like receptor pathway, its association with TBK1 results in autophage-lysosomal degradation of TBK1, thus abrogating the downstream IFN induction. Interestingly, FTRCA1 is phosphorylated by TBK1, but this phosphorylation is not required for downregulation of TBK1 protein. Transfection assays indicate that FTRCA1 is likely an E3 ligase with the requirement of RING finger domain, and deletion of N-terminal RING domain or mutation of seven conservative sites abolishes the negative regulatory function of FTRCA1. Collectively, these results illuminate a novel finTRIM-mediated innate immune modulatory pathway, thus providing insights into species-specific regulation of fish IFN response. [ABSTRACT FROM AUTHOR]

Abstract Stress response has negative effect on fish in aquaculture and research, which can be alleviated with anesthetic. To determine the optimal anesthetic, we investigated the physiological response of crucian carp (Carassius auratus) treated with three different anti-stress treatments: MS-222, eugenol and percussive stunning. Stress responses were evaluated by analyzing serum cortisol level and gene expression in blood. We determined the optimal concentrations of MS-222 (100 mg L−1) and eugenol (20 mg L−1) by dose selection. We found that the control group had significantly higher cortisol levels (172.78 ± 19.95 ng mL−1) compared to the MS-222 treated group (46.85 ± 3.22 ng mL−1), the eugenol treated group (72.78 ± 9.07 ng mL−1), and the stunning treatment group (82.78 ± 8.16 ng mL−1). Transcriptome analysis revealed 1572 differentially expressed genes (DEGs), including 155 DEGs related to the stress response, mainly involved in oxidative-stress response, heat shock proteins, and cold shock domain-containing protein. The heat shock protein genes were the primary DEGs in response to stress. RT-qPCR analysis confirmed differential expression of Hsps. We analyzed the function of the DEGs, which were enriched in genes involved in cellular response to stress and antigen processing and presentation. Combining the results from biochemical, transcriptome, and gene expression analysis, our data suggest that eugenol is more effective than MS-222 and percussive stunning in alleviating stress in crucian carp. Highlights • Anesthesia alleviates routine handling stress in crucian carp. • Optimal concentrations for MS-222 and eugenol are reported. • Stress-induced cortisol increases are alleviated by anesthesia in crucian carp. • Stress-induced expression of heat shock proteins is reduced by anesthesia. • Eugenol is suggested to be the optimal anesthetic for carp research and aquaculture. [ABSTRACT FROM AUTHOR]

Fish typically prefer to live in big shoals due to the associated ecological benefits. Shoaling is a behavior that depends on the ability to quantitatively discriminate. The fundamental mechanism involved in quantity discrimination determines whether fish can discriminate a shoal using numerical discrete cues (e.g., number of shoal members), non-numerical continuous traits (e.g., total body surface area) or both; however, the mechanism is currently a controversial topic. In the present study, we used a spontaneous choice experiment to test whether guppy (Poecilia reticulata), zebrafish (Danio rerio), Chinese crucian carp (Carassius auratus) and qingbo (Spinibarbus sinensis) rely on continuous (i.e., body surface area) or discrete (i.e., number of shoal members) information for shoal selection by altering the body surface area (cumulative body surface area ratio of 3:2 or 1:1) between two stimulus shoals with a different number of members (2 individuals vs 3 individuals). All four fish species preferred to shoal with the stimulus shoal with the larger cumulative surface area even if the shoal had fewer members; however, fish showed no shoal preference when the cumulative surface body areas of both stimulus shoals were equal. Furthermore, qingbo did not numerically discriminate between a shoal with 1 individual and a shoal with 3 individuals when the cumulative surface areas of both stimulus shoals were equal; however, qingbo showed a preference for the shoal with the larger cumulative surface area when the two stimulus shoals each had 3 individuals. In conclusion, the present study demonstrated that all four fish species relied only on non-numerical continuous quantity information for shoal selection, at least under a difficult task (i.e., 2 vs 3). [ABSTRACT FROM AUTHOR]

Crucian carp (Carassius carassius) survive without oxygen for several months, but it is unknown whether they are able to protect themselves from cell death normally caused by the absence, and particularly return, of oxygen. Here, we quantified cell death in brain tissue from crucian carp exposed to anoxia and re-oxygenation using the terminal deoxy-nucleotidyl transferase dUTP nick-end labelling (TUNEL) assay, and cell proliferation by immunohistochemical staining for proliferating cell nuclear antigen (PCNA) as well as PCNA mRNA expression. We also measured mRNA and protein expression of the apoptosis executer protease caspase 3, in laboratory fish exposed to anoxia and re-oxygenation and fish exposed to seasonal anoxia and reoxygenation in their natural habitat over the year. Finally, a behavioural experiment was used to assess the ability to learn and remember how to navigate in a maze to find food, before and after exposure to anoxia and re-oxygenation. The number of TUNEL-positive cells in the telencephalon increased after 1 day of re-oxygenation following 7 days of anoxia, indicating increased cell death. However, therewere no consistent changes in whole-brain expression of caspase 3 in either laboratory-exposed or naturally exposed fish, indicating that cell death might occur via caspase-independent pathways or necrosis. Re-oxygenated crucian carp appeared to have lost the memory of how to navigate in a maze (learnt prior to anoxia exposure), while the ability to learn remained intact. PCNA mRNA was elevated after re-oxygenation, indicating increased neurogenesis. We conclude that anoxia tolerance involves not only protection from damage but also repair after re-oxygenation. [ABSTRACT FROM AUTHOR]

Fish gut microbiota play important roles in fish immunity, nutrition, and the adaptation to environmental changes. To date, few studies have focused on the interactions among environmental factors, fish diseases, and gut microbiota compositions. We compared the gut bacterial communities of healthy crucian carps ( Carassius auratus) with those of individuals affected by 'red-operculum' disease and corresponding water and sediment microbiota in four fish farm ponds. Distinct gut bacterial communities were observed in healthy and diseased fish. The bacterial communities of diseased fish were less diverse and stable than those of healthy individuals. The differences in bacterial community compositions between diseased and healthy fish were explained by the changes in the relative abundances of some specific bacterial OTUs, which belonged to the genera such as Vibrio, Aeromonas, and Shewanella, and they were prevalent in diseased fish, but rare or even absent in environmental samples. Water temperature and ammonia concentration were the two most important environmental factors that impacted gut microbiota in diseased fish. These results highlighted the surge of some potential pathogens as bacterial signatures that were associated with 'red-operculum' disease in crucian carps. [ABSTRACT FROM AUTHOR]

It is well known that aluminium is the principle toxicant killing fish in acidified freshwater systems, and it has been shown that crucian carp (Carassius carassius) can survive exposures to aqueous aluminium levels toxic to most other freshwater fish species. The crucian carp has a remarkable ability to survive anoxic conditions, and the aim of the present study was to reveal if the tolerance to aluminium can be associated with the ability to survive prolonged anoxia. Crucian carps were exposed to either acidic Al-rich water (pH 5.8; 960 μg Al/l), acidic Al-poor water (pH 5.8; 50 μg Al/l) or untreated control water (pH 6.5; 50 μg Al/l). Blood, muscle and gill samples were collected from exposed fish, and closed respirometry was performed to measure critical O2-tension an normoxic O2-consumption. The results show an increased gill surface area in Al-exposed fish, while the critical O2-tension did not change. The normoxic O2-consumption was lower in Al-exposed fish and might be due to a reduced metabolic rate. The results suggest that crucian carp exposed to aluminium do not become hypoxic, since haematocrit, plasma lactate and blood ethanol did not differ from that of control fish after 14 days of exposure. We also observed an initial loss of plasma chloride and sodium, followed by a stabilisation of these ions at a lower level than in control fish. The decrease in plasma ions caused a transient increase in haematocrit and water content in muscle tissue, returning to control levels when the ion concentrations stabilised, suggesting that the water balance was restored. We conclude that the high tolerance to aluminium in crucian carp is associated with its ability to avoid hypoxia as well as an ability to counteract a continuous loss of plasma ions. [ABSTRACT FROM AUTHOR]

Mobilization of glycogen stores was examined in the anoxic crucian carp ( Carassius carassius Linnaeus). Winter-acclimatized fish were exposed to anoxia for 1, 3, or 6 weeks at 2 °C, and changes in the size of glycogen deposits were followed. After 1 week of anoxia, a major part of the glycogen stores was mobilized in liver (79.5 %) and heart (75.6 %), and large decreases occurred in gill (46.7 %) and muscle (45.1 %). Brain was an exception in that its glycogen content remained unchanged. The amount of glycogen degraded during the first anoxic week was sufficient for the anaerobic ethanol production for more than 6 weeks of anoxia. After 3 and 6 weeks of anoxia, there was little further degradation of glycogen in other tissues except the brain where the stores were reduced by 30.1 and 49.9 % after 3 and 6 weeks of anoxia, respectively. One week of normoxic recovery following the 6-week anoxia was associated with a complete replenishment of the brain glycogen and partial recovery of liver, heart, and gill glycogen stores. Notably, the resynthesis of glycogen occurred at the expense of the existing energy reserves of the body in fasting fish. These findings indicate that in crucian carp, glycogen stores are quickly mobilized after the onset of anoxia, with the exception of the brain whose glycogen stores may be saved for putative emergency situations. [ABSTRACT FROM AUTHOR]

The comparative pharmacokinetics of enrofloxacin ( ENR) and its metabolite ciprofloxacin ( CIP) were investigated in healthy and Aeromonas hydrophila-infected crucian carp after a single oral (p.o.) administration at a dose of 10 mg/kg at 25 °C. The plasma concentrations of ENR and of CIP were determined by HPLC. Pharmacokinetic parameters were calculated based on mean ENR concentrations by noncompartmental modeling. In healthy fish, the elimination half-life ( T1/2 λz), maximum plasma concentration ( Cmax), time to peak ( Tmax), and area under the concentration-time curve ( AUC) values were 64.66 h, 3.55 μg/ mL, 0.5 h, and 163.04 μg·h/ mL, respectively. In infected carp, by contrast, the corresponding values were 73.70 h, 2.66 μg/ mL, 0.75 h, and 137.43 μg·h/ mL, and the absorption and elimination of ENR were slower following oral administration. Very low levels of CIP were detected, which indicates a low extent of deethylation of ENR in crucian carp. [ABSTRACT FROM AUTHOR]

This study investigated the concentrations of phenolic endocrine-disrupting chemicals (EDCs) and the incidence of ovo-testis (intersex) in wild crucian carp ( Carassius carassius ) sampled from the Hun River. As expected, nonylphenols (NP) and bisphenol A (BPA) were detected in all samples, and octylphenols (OP) were found in most samples. NP concentrations ranged from 1290 ± 584 to 3111 ± 2071 ng g −1 wet weight (ww) in July and from 1132 ± 644 to 1556 ± 587 ng g −1 ww in November; OP ranged from 6 ± 7 to 46 ± 38 ng g −1 ww in July and from no detection to 22 ± 16 ng g −1 ww in November; and BPA ranged from 4 ± 9 to 41 ± 24 ng g −1 ww in July and from 6 ± 5 to 59 ± 24 ng g −1 ww in November. Moreover, the concentrations of these compounds were higher in fish found down-stream of the sewage treatment plant (STP), and the lowest concentrations were found in fish up-stream of the STP. Concentrations of these EDCs in muscles might be correlated with the prevalence of intersex traits in wild fish, suggesting that these compounds contribute, at least in part, to the occurrence of intersex morphology. Thus, phenolic EDCs discharged from the STP pose a risk to the aquatic ecosystem in the Hun River. [ABSTRACT FROM AUTHOR]

Over the past few decades, endosulfan, one of the polychlorinated pesticides still in use, has received considerable attention of a number of international regulations and restriction action plans worldwide. This study aimed to evaluate the cytogenetic effects of endosulfan using robust genotoxicity assays, along with the oxidative stress pathways in order to understand biochemical mechanism, in Carassius carassius L. The LC 50–96 h (95% confidence limits) value of endosulfan was 0.070 (0.046–0.093) ppm; and on its basis three test concentrations (sub-lethal I: 0.052, II: 0.035 and III: 0.017 ppm) were selected for 35 d in vivo exposure. The mean concentration of endosulfan in aquaria was always constant, when analyzed by dispersive liquid–liquid micro extraction (DLLME) followed by GC–MS. Autopsy was done on days 1, 2, 3, 4, 7, 14, 21, 28 and 35 of endosulfan exposure; the micronucleus formation (MN), authenticated by scanning electron microscopy, and chromosomal aberrations (CA), were induced significantly ( p < 0.05) in all the treated groups, including positive control cyclophosphamide (4 ppm), when compared to negative control. Similarly lipid peroxidation (LPO) was induced significantly with the maximal at higher concentration (SL-I) on 4th day (722.45%; p < 0.01). Antioxidant biomarkers like glutathione reduced, superoxide dismutase and catalase also fluctuated significantly ( p < 0.01) in all treatment groups. Collective findings demonstrated that genotoxic effects were invariably accompanied and correlated with increased oxidative stress and disturbance of antioxidant enzymes; and the MN and CA assays are useful tools in determining potential genotoxicity of aquatic xenobiotics and might be appropriate as a part of monitoring program. [ABSTRACT FROM AUTHOR]

Crucian carp are unusual among vertebrates in surviving extended periods in the complete absence of molecular oxygen. During this time cardiac output is maintained though these mechanisms are not well understood. Using a high-density cDNA microarray, we have defined the genome-wide gene expression responses of cardiac tissue after exposing the fish at two temperatures (8 and 13°C) to one and seven days of anoxia, followed by seven days after restoration to normoxia. At 8°C, using a false discovery rate of 5%, neither anoxia nor re-oxygenation elicited appreciable changes in gene expression. By contrast, at 13°C, 777 unique genes responded strongly. Up-regulated genes included those involved in protein turnover, the pentose phosphate pathway and cell morphogenesis while down-regulated gene categories included RNA splicing and transcription. Most genes were affected between one and seven days of anoxia, indicating gene regulation over the medium term but with few early response genes. Re-oxygenation for 7 days was sufficient to completely reverse these responses. Glycolysis displayed more complex responses with anoxia up-regulated transcripts for the key regulatory enzymes, hexokinase and phosphofructokinase, but with down-regulation of most of the non-regulatory genes. This complex pattern of responses in genomic transcription patterns indicates divergent cardiac responses to anoxia, with the transcriptionally driven reprogramming of cardiac function seen at 13°C being largely completed at 8°C. [ABSTRACT FROM AUTHOR]

The occurrence and fate of endocrine disrupting chemicals (EDCs) in aquatic species have attracted close attention during the last decades. In this study, the bioaccumulation and biotransformation of synthetic estrogen quinestrol, one of the typical EDCs, in the plasma and liver of crucian carp, were investigated by a newly developed and validated reversed-phase high performance liquid chromatography with fluorescent detection method. Crucian carp were exposed to quinestrol in concentration of 2, 10, 50, 100 µg/L (5.49, 27.43, 137.17, 274.34 nmol/L) for 60 days. After 60 days' exposure, the concentrations of quinestrol found in liver and plasma were in the range of 0.25-0.69 mg/kg and 0.19-0.30 mg/L respectively, positively correlated with the exposure concentrations ranged 2-100 µg/L (5.49-274.34 nmol/L). There was a negative correlation between the bio-accumulation ratios and the exposure concentrations of quinestrol. 17α-Ethinylestradiol was also found in liver and plasma, and the concentrations were 0.02-0.19 mg/kg and 0.37-0.96 mg/L, respectively. The results indicated that quinestrol can be accumulated and transformed to 17α-ethinylestradiol in crucian carp. Moreover, exposure to quinestrol caused oxidative damages to crucian carp and the content of malondialdehyde increased in all treatment concentrations. [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]

Both sexual reproduction and unisexual reproduction are adaptive strategies for species survival and evolution. Unisexual animals have originated largely by hybridization, which tends to elevate their heterozygosity. However, the extent of genetic diversity resulting from hybridization and the genomic differences that determine the type of reproduction are poorly understood. In Carassius auratus, sexual diploids and unisexual triploids coexist. These two forms are similar morphologically but differ markedly in their modes of reproduction. Investigation of their genomic differences will be useful to study genome diversity and the development of reproductive mode. We generated transcriptomes for the unisexual and sexual populations. Genes were identified using homology searches and an ab initio method. Estimation of the synonymous substitution rate in the orthologous pairs indicated that the hybridization of gibel carp occurred 2.2 million years ago. Microsatellite genotyping in each individual from the gibel carp population indicated that most gibel carp genes were not tri-allelic. Molecular function and pathway comparisons suggested few gene expansions between them, except for the progesterone-mediated oocyte maturation pathway, which is enriched in gibel carp. Differential expression analysis identified highly expressed genes in gibel carp. The transcriptomes provide information on genetic diversity and genomic differences, which should assist future studies in functional genomics. [ABSTRACT FROM AUTHOR]

The seasonal diet of the Eurasian otter (Lutra lutra) was studied on Alazani river, eastern Georgia, by spraint analysis. The frequency of occurrence (FO) of prey items for fish species, and biomass consumed (BC) were estimated. Fish and amphibians formed the bulk of the otter diet in the study area (49.8-30.0% FO and 23.6-36.2% FO, in the cold and warm season, respectively). Reptiles (Natrix tessellata and N. natrix) were also important (11.5% and 13.4%). Mammals (mice and muskrats), birds, insects (Dytiscidae and Acridoidea), molluscs and crayfish formed a minor part of the diet. Crucian carp (Carassius carassius) and common carp (Cyprinus carpio) were the most important fish in the otter diet, while, and with regard to amphibians only Rana ridibunda was found. Food niche breadth in the warm season was about twice as much as in the cold one. Crucian carp predominated in the diet in both the warm (37.9% BC and 52.0% FO, respectively) and cold season (90.4% BC and 82.0% FO). [ABSTRACT FROM AUTHOR]

Abstract: Both nitrite (NO2–N) and dissolved oxygen (DO) are key water quality factors and can impact on aquatic animals'' health. In this study, juvenile crucian carp Carassius auratus were exposed to different concentrations of NO2–N (0, 2.5, and 5 mg L−1) and DO (2 and 6 mg L−1) for 30 days. Results showed that under low DO conditions there was a decrease in specific growth rate, feeding rate, food conversion efficiency, and protein efficiency ratio. Red blood cell count (RBC) increased significantly with decreasing DO; three-way ANOVA indicated that there was a statistically significant interaction between DO and NO2–N on RBC. Hemoglobin content of fish exposed to low DO levels was significantly higher than that in the normal DO. Changes in the enzymatic (SOD and CAT) and non-enzymatic (GSH) antioxidants in fish liver and blood exhibited oxidative stress occurred under the conditions of low DO and high NO2–N. [Copyright &y& Elsevier]

Abstract: Polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) are two major flame retardants that accumulate in fish tissues and are potentially toxic. Their debrominated and oxidated derivatives were also reported in fish tissues although the sources of theses derivatives were unidentified. Our study was to determine whether PBDEs and TBBPA could be metabolized by fish liver subcellular fractions in vitro and to identify what types of metabolites were formed. Liver microsomes and S9 fractions of crucian carp (Carassius auratus) were exposed to 4,4′-dibromodiphenyl ether (BDE 15), 2,2′,4,4′-tetrabromodiphenyl ether (BDE 47) or TBBPA solutions for 4h. Exposure of liver subcellular fractions to BDE 15 resulted in the formation of bromophenol and two monohydroxylated dibromodiphenyl ether metabolites. Neither in microsomes nor in S9 studies has revealed the presence of hydroxylated metabolites with BDE 47 exposure which indicated that the oxidation reactions in vitro were hindered by the increased number of bromine substituents on the PBDEs. TBBPA underwent an oxidative cleavage near the central carbon of the molecule, which led to the production of 2,6-dibromo-4-isopropyl-phenol and three unidentified metabolites. Another metabolite of TBBPA characterized as a hexa-brominated compound with three aromatic rings was also found in the liver subcellular fractions. These results suggest that the biotransformation of BDE 15 and TBBPA in fish liver is mediated by cytochrome P450 (CYP450) enzymes, as revealed by the formation of hydroxylated metabolites and oxidative bond cleavage products. Moreover, further studies on the identification of specific CYP450 isozymes involved in the biotransformation revealed that CYP1A was the major enzyme responsible for the biotransformation of BDE 15 and TBBPA in fish liver subcellular fractions and CYP3A4 also played a major role in metabolism of TBBPA. [Copyright &y& Elsevier]

Gill remodeling can be extensive in crucian carp, where up to a 7.5-fold increase in gill surface area has been observed during exposure to hypoxia through a reduction in the interlamellar cell mass (ILCM) and increased lamellar protrusion that has been hypothesized to be signaled by the need to maximize oxygen uptake under a given condition. Sustained aerobic exercise may have the greatest influence on oxygen demand in fish; however, its effect on gill remodeling in crucian carp has not been investigated. The specific objectives of this study were to determine (i) whether sustained aerobic exercise induces gill remodeling in the crucian carp, (ii) whether gill remodeling following sustained exercise affects the maximum critical swimming speed (Ucrit) and maximal oxygen consumption rate (MO2), and (iii) whether gill remodeling following sustained exercise is associated with trade-offs related to ionoregulation. We measured MO2 in crucian carp at each step during an initial Ucrit test (Ucrit1), forced them to swim at 70% of Ucrit for 40 h, and then conducted a second Ucrit test (Ucrit2). From rest to Ucrit1 (7-8 h), we observed a significant increase in protruding lamella height and area of the gills and a reduction in ILCM height and volume, likely associated with partial shedding of the ILCM, indicating that gill remodeling during exercise is rapid. Further changes were observed between Ucrit1 and Ucrit2, with statistically significant increases in protruding lamellar height, basal length and area, and a statistically significant reduction in protruding lamellar thickness and ILCM height and volume. Interestingly, there was no significant difference between Ucrit1 and Ucrit2 values, nor in maximal MO2 measured at Ucrit1 and Ucrit2. Furthermore, there was no significant difference in plasma osmolarity, [Na+ ], or [Cl- ] in fish at rest, following Ucrit1 or Ucrit2. Thus, while these data support the hypothesis that the need to maximize oxygen uptake is an important signal for gill remodeling, which can occur quite rapidly (within 7 h at 15°C), the physiological implications of remodeling during exercise are less clear. [ABSTRACT FROM AUTHOR]

Seasonal habitat use by nigorobuna Carassius auratus grandoculis Temminck et Schlegel and gengoroubuna Carassius cuvieri (Temminck et Schlegel) in Lake Biwa was investigated using acoustic telemetry. Twenty-three nigorobuna and 11 gengoroubuna specimens caught using set-nets in the lake's south basin were surgically fitted with acoustic transmitters and then released. Signals from the fishes were recorded by 23 receivers installed around the lake. Between April and June 2007, the first spawning season after release, signals were received from all tagged fishes. Thereafter, until the second spawning season, signals were collected from 26 and 45% of released nigorobuna and gengoroubuna individuals, respectively. Seasonal habitat preferences for these species were studied by distance-based analysis. The analysis revealed that nigorobuna tended to stay near their spawning area in the south basin of the lake throughout the year, whilst gengoroubuna tended to show a seasonal migration pattern between the north and south basins. After the spawning season, the latter species migrated to the north basin where it remained until the next spawning season, when it returned to the south basin. This is the first report of seasonal migration of nigorobuna and gengoroubuna in Lake Biwa. [ABSTRACT FROM AUTHOR]

PCR-RFLP analysis of the ND3/ND4L/ND4 and 12S/16S rRNA regions and nucleotide sequence variation of the cytochrome b gene were used to study the mtDNA divergence in species of the family Cyprinidae, to examine the phylogenetic relationships of the species, and to identify their taxonomic status. The results indicated that an ancestral form diverged into silver crucian carp and crucian carp after its separation from the common carp lineage. The divergence of continental Carassius auratus gibelio and Japanese C. auratus cuvieri occurred more recently. Two well distinguishable mtDNA phylogroups, suggesting divergent evolution, were observed in continental C. auratus gibelio populations. The divergence was possibly related to the formation of two silver crucian carp groups with different types of reproduction, triploid gynogenetic and diploid gonochoric. At the same time, the results supported the high probability of current genetic exchange between the forms. In view of these findings and high morphological similarity of the two forms, they were not considered to be separate species. [ABSTRACT FROM AUTHOR]

Rice-fish culture, which means the simultaneous culture of rice and fish, is one of the best options to increase food production from limited land and is practiced in many countries in the world. Although many researchers and farmers believe that the rice yield is increased by fish farming in paddy fields, this hypothesis has never been fully tested. Here, we report ecological processes leading to higher rice yields in the rice-fish culture using crucian carp ( Carassius complex), which have adapted to the paddy field ecosystem in Japan. We compare the rice-fish and rice-only plots in the experimental paddy field for biota, water quality, and rice yield. Coverage of duckweed and densities of zooplankton and benthic invertebrates in the rice-fish plots were lower than those in the rice-only plots, indicating that fish utilized them as food. NO-N concentration in the rice-fish plots was higher than that in the rice-only plots, indicating that the increase in NO-N concentration results from excretion of unutilized food nutrients by the fish. Consequently, rice yield in the rice-fish plots was 20% higher than that in the rice-only plots. The fertilizing effect of the fish excrement probably increased rice yield. [ABSTRACT FROM AUTHOR]

Biometric data are presented for different fish species captured in four lakes of Turkey: crucian carp (Carassius gibelio), common carp (Cyprinus carpio), chub (Squalius cephalus), and pikeperch (Sander lucioperca). The length, breadth, and weight of otolith, (sagitta, asteriscus, and lapillus) were determined, and the relationships between otolith size and fork length were defined. All regressions were highly significant (P<0.05). In cyprinid fishes, (C. gibelio, C. carpio, and S. cephalus), asteriscus weight had the highest coefficient of determination among the asteriscus biometrics, and the lapillus length had the highest coefficient of determination among lapillus measurements for the same species. In S. lucioperca (Percidae), sagittal otolith weight was the best predictor of fish length. [ABSTRACT FROM AUTHOR]

Four goldfish Carassius auratus morphotypes of similar length (50 mm): common (streamlined, full complement of paired and median fins, bifurcated caudal fin), comet (‘common like’ but with a long, deeply forked caudal fin), fantail (short, deep body with twinned caudal and anal fins) and eggfish (similar to the fantail but lacking a dorsal fin) were compared. Drag, steady swimming kinematics, energetics, fast-start performance, stability in yaw and roll and propulsive muscle ultrastructural characteristics were measured. A performance ‘pairing’ (common and comet; fantail and eggfish) was a recurrent theme for most performance variables. Fantail and eggfish drag were higher (requiring more thrust at any given velocity) than those for the more streamlined common and comet. This was reflected in kinematics; tailbeat frequency and stride length at any given velocity for the common and comet were lower and higher, respectively, than that of the fantail and eggfish. Common and comet fatigue times were not significantly different from those of their ancestor, crucian carp Carassius carassius, and higher than the fantail and eggfish. The cost of transport of the common and comet (c. 0• 6 mg O2 kg−1 m−1) was accurately predicted by the mass scaling relationship for fish, but values for the fantail and eggfish (c. 1• 3 mg O2 kg−1 m−1) were not. Rolling and yawing motions in eggfish (dorsal fin absent) during steady swimming were associated with significant energy losses. Eggfish maximum fast-start acceleration (c. 5 m s−2) was poor due to the absence of inertial and lifting contributions to thrust from the dorsal fin and energy wasting rolling motions. Common and comet fast-start performance (average velocity c. 0• 45 m s−1, maximum velocity c. 1• 2 m s−1, average acceleration c. 7• 5 m s−2, maximum acceleration c. 35 m s−2) was similar to that of other locomotor generalists (e.g. rainbow trout Oncorhynchus mykiss). Artificially selected fishes can contribute to the understanding of form and movement in fishes and complement studies of the role of locomotor adaptations in natural systems. [ABSTRACT FROM AUTHOR]

Effects of feeding on pre-exercise VO2 and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise were investigated in sedentary southern catfish, active herbivorous grass carp, omnivorous crucian carp, and sluggish omnivorous darkbarbel catfish to test whether feeding had different effects on EPOC and to compare EPOC in fishes with different ecological habits. For fasting fish, the pre-exercise and peak post-exercise VO2 were higher and recovery rates were faster in crucian carp and grass carp compared to those of darkbarbel catfish and southern catfish. EPOC magnitudes of grass carp and southern catfish were significantly larger than those of crucian carp and darkbarbel catfish. Feeding had no significant effect on peak post-exercise VO2, recovery rate, and EPOC magnitude in grass carp. Both the pre-exercise and peak post-exercise VO2 increased with meal size, while the EPOC magnitude and duration decreased significantly in the larger meal size groups of crucian carp and southern catfish. In darkbarbel catfish, both the pre-exercise and peak post-exercise VO2 increased with meal size, but the VO2 increment elicited by exercise was larger in feeding groups compared with the fasting group. These results suggest that (1) the characteristics of the post-exercise VO2 profile, such as peak post-exercise VO2 and recovery rate, were closely related to the activity of fishes, whereas the EPOC magnitude was not and (2) the effects of feeding on EPOC were more closely related to the postprandial increase in VO2. [ABSTRACT FROM AUTHOR]

Injured fish skin leaks alarm substances that induce the fright reaction upon olfactory detection. The skin also contains a multitude of other odorants traditionally related to other behaviors, but to what extent they are detected upon injury is unknown. We have performed single unit recordings in the olfactory bulb (OB) of crucian carp while exposing the olfactory epithelium to skin extracts from conspecifics and three other species of the carp family, common carp, tench and bream. The aims were to investigate whether neural activity may be induced by different types of skin odorants and how well the odorants from injured conspecifics are distinguished from other species. The OB of crucian carp shows a clear chemotopy as units located in different regions respond to either food-related odorants, to pheromones or to alarm odorants respectively. Units in all regions responded to skin extracts, which indicate the detection of odorants usually involved in reproduction and feeding, in addition to the alarm substances. Among OB units responding to only one of the skin extracts, most were sensitive to conspecific skin extract. Furthermore, pair-wise comparisons showed that the discrimination between conspecific skin extract and skin extract from another species was in general better than the discrimination between skin extracts from two heterospecifics. The findings suggest that identification of injured fishes may be based on different groups of odorants and that the crucian carp olfactory system discriminates well between odorants from conspecifics and those from other fish species. [ABSTRACT FROM AUTHOR]

While a large respiratory surface area is good for gas exchange, it also poses several problems, including energetically unfavorable fluxes of water and ions. As a result, fishes appear to have a respiratory surface area that is matched to their oxygen demands. When faced with changes in their need for oxygen uptake, e.g. through altered physical activity or altered ambient oxygen levels, fishes have long been known to make two different adjustments: (1) to change the water flow over the gills or (2) to change the blood flow inside the gills. It has recently become clear that at least some teleosts have a third option: to reversibly remodel the gill morphology. Studies have shown that the lamellae of crucian carp Carassius carassius gills are embedded in a cell mass during normoxic conditions or at low temperature, while much of this cell mass dies off in hypoxia and at higher temperatures, thereby exposing a much larger respiratory surface area. Gill remodeling has subsequently been seen in two more cyprinids and in the mangrove killifish Kryptolebias marmoratus. In the latter case it appears to be an adaptation to periods of air exposure. Gill remodeling in response to changing respiratory requirements could be an ancient mechanism, occurring in many more teleosts than presently known. It is tempting to suggest that gill remodeling has been overlooked in many fishes, either because it is relatively subtle in some species, or because fishes are often kept at the warmer end of their temperature range where they need fully protruding lamellae. [ABSTRACT FROM AUTHOR]

Pengze crucian carp (Carassius auratus of pengze), just like silver crucian carp, is known to be a gynogenetic crucian carp. It is one of the most popular cultured fishes in China. The offspring developed from pengze crucian carp eggs activated by heterologous sperm shows obvious allogynogenetic biological effects in growth and fertilization rate, although the offspring is almost the same in morphology as the maternal pengze crucian carp. Recently, a multiple tetraploid form, which showed obvious morphological changes compared with the normal allogynogenetic offspring, was found in the offspring developed from pengze crucian carp eggs stimulated by sea carp (Cyprinus acutidorsalis Wang) sperm. In this paper, the chromosome number and karyotype of the multiple tetraploid form and its parents were analyzed, using chromosomes of kidney cell-PHA culture in vivo prepared by flame-drying technique. The paternal sea carp had 2n=100 diploid chromosomes and the karyotype of 28 metacentric, 24 submetacentric, 26 subtelocentric and 22 telocentric, NF=152. The maternal pengze crucian carp had 156 chromosomes in its karyotype, with 42 metacentric, 36 submetacentric, 39 subtelocentric, 33 telocentric, and 6 supernumerary microchromosomes. The karyotype of the multiple tetraploid allogynogenetic pengze crucian carp contained 206 chromosomes, with 56 metacentric, 48 submetacentric, 44 subtelocentric, 52 telocentric, and 6 supernumerary microchromosomes. Both the multiple tetraploid form and its maternal parent had six supernumerary microchromosomes. The results indicated that the chromosomes of the multiple tetraploid allogynogenetic pengze crucian carp consist of the whole maternal chromosome set and a haploid paternal chromosome set, which suggests that a few of the gynogenetic pengze crucian carp eggs have the gonochoristic reproductive ability to integrate with heterologous sperm nuclei. [Copyright &y& Elsevier]

The present study was designed to test the hypothesis that temperature acclimation modifies sarcolemmal Na+ current (INa) of the fish cardiac myocytes differently depending on the animal's lifestyle in the cold. Two eurytherm4al fish species with different physiological strategies for surviving in the cold, a cold-dormant crucian carp (Carassius carassius L.) and a cold-active rainbow trout (Oncorhynchus mykiss), were used in acclimation experiments. The INa of carp and trout were also compared with INa of a cold stenothermal burbot (Lota lota). In accordance with the hypothesis, cold-acclimation decreased the density of INa in crucian carp and increased it in rainbow trout, suggesting depression of impulse conduction in cold-acclimated carp and positive compensation of impulse propagation in cold-acclimated trout. The steady-state activation curve of trout INa was shifted by 6 mV to more negative voltages by cold acclimation, which probably lowers the stimulus threshold for action potentials and further improves cardiac excitability in the cold. In burbot myocytes, the INa density was high and the position of the steady-state activation curve on the voltage axis was even more negative than in trout or carp myocytes, suggesting that the burbot INa is adapted to maintain high excitability and conductivity in the cold. The INa of the burbot heart differed from those of carp and trout in causing four times larger charge influx per excitation, which suggests that INa may also have a significant role in cardiac excitation-contraction coupling of the burbot heart. In summary, INa of fish cardiac myocytes shows thermal plasticity that is different in several respects in cold-dormant and cold-active species and thus has a physiologically meaningful role in supporting the variable life styles and habitat conditions of each species. [ABSTRACT FROM AUTHOR]

Summary The crucian carp, Carassius carassius (L.), is a small fish of restricted distribution in the UK, which is probably only native to central and eastern England. The crucian carp is endemic to northern Europe. It has been widely confused with the introduced and congeneric goldfish, Carassius auratus (L.), and forms hybrids with that species and the introduced Cyprinus carpio L. The status of this fish has become confused with the presence of the congener and its hybrids, and it is now thought to be less frequent in occurrence than formerly. [ABSTRACT FROM AUTHOR]

Results of a 16 year (1977–1992) study of hybrids obtained from crossing two cyprinid fish, crucian carp. Carassius auratus gibelio (Bloch) (bisexual form), and common carp, Cyprinus carpio L., are presented. The ability to produce diploid eggs in F1 females (resulting from chromosome endoreduplication in early oogenesis) was responsible for the high yield of spontaneous diploids in gynogenetic progenies of F1 females and for triploidy in hybrids from back-crosses of F1 females with males of the parent species. Different types of hybrids, including diploid and triploid gynogenetic, tetraploid (amphidiploid) and androgenetic progenies, were obtained. Diploid and some triploid hybrids (females only) were reproduced inter se by induced gynogenesis in several subsequent gynogenetic generations. Amphidiploid hybrids were obtained by crossing triploid FB females with diploid common carp males or by crossing diploid gynogenetic females with diploid inverted hybrid males producing diploid sperm. Results of cytogenetic investigations and fish culture properties in hybrids are presented. The scientific and practical significance of the data obtained are discussed. [ABSTRACT FROM AUTHOR]

• A method for fish mass estimation based on PCA-CF and neural network is proposed. • The CF method we proposed is used for calculating feature values. • The proposed method performs better than the common fish mass estimation methods. • The proposed method is simple and easy that is suitable for actual aquaculture. It is of great significance to accurately estimate the fish mass in their different growth stages for achieving reasonable feeding, promoting healthy growth and improving breeding efficiency. In current fish mass estimation methods, the distance between the image acquisition device and the target fish is generally needed to be fixed, which limits the practicability of these methods in actual aquaculture. Aiming at the above problem, through image analysis, a fish mass estimation method based on principal component analysis - calibration factor (PCA-CF) and neural network was proposed. Firstly, image segmentation, image enhancement, and other preprocessing operations were carried out on these collected fish images. Secondly, fish image features were extracted using the PCA method and feature values were calculated by the CF method. Finally, the fish mass was estimated by the back-propagation neural network (BPNN) algorithm. In this paper, the proposed method CF was used to calculate the fish images feature values, which solved the problem that the distance between the acquisition device and the target fish is inconsistent, affecting the fish mass estimation accuracy. Crucian carp was taken as the experimental object and the proposed fish mass estimation method has been tested on the real dataset with the mean absolute error (MAE) of 0.0104, the root mean square error (RMSE) of 0.0137 and the coefficient of determination (R2) of 0.9021. Furthermore, when compared with the BPNN-Weight, Support Vector Regression (SVR)-Weight, Linear Discriminant Analysis (LDA)-CF-BPNN, PCA-CF-Decision Tree (DT), PCA-CF- k-Nearest Neighbor (KNN), Length-Weight, Area-Weight, and Multiple-factor-Weight fish mass estimation methods, the performance of each evaluation metric of the proposed method was improved. The experimental results indicated that the proposed method can accurately estimate the fish mass. [ABSTRACT FROM AUTHOR]

Although comprehending the significance of phenotypic plasticity for evolution is of major interest in biology, the pre-requirement for that, the understanding of variance in plasticity, is still in its infancy. Most researchers assess plastic traits at single developmental stages and pool results between sexes. Here, we study variation among sexes and developmental stages in inducible morphological defences, a well-known instance of plasticity. We raised fathead minnows, Pimephales promelas, under different levels of background predation risk (conspecific alarm cues or distilled water) in a split-clutch design and studied morphology in both juveniles and adults. In accordance with the theory that plasticity varies across ontogeny and sexes, geometric morphometry analyses revealed significant shape differences between treatments that varied across developmental stages and sexes. Alarm cue-exposed juveniles and adult males developed deeper heads, deeper bodies, longer dorsal fin bases, shorter caudal peduncles and shorter caudal fins. Adult alarm cue-exposed males additionally developed a larger relative eye size. These responses represent putative adaptive plasticity as they are linked to reduced predation risk. Perhaps most surprisingly, we found no evidence for inducible morphological defences in females. Understanding whether similar variation occurs in other taxa and their environments is crucial for modelling evolution. [ABSTRACT FROM AUTHOR]

In this study, the complete mitochondrial genome sequence ofCarassius auratus var. high back crucian carp(C. auratus var.) was determined (GenBank accession number is KT756205). The mitochondrial genome sequence ofC. auratus var. was a circular molecule with 16 581 bp in length, and contained 37 typical animal mitochondrial genes, including 2 ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes and a control region (D-loop). Four nucleotide compositions and their relative proportions of the entire mitogenome was 26.19% C, 16.06% G, 31.57% A and 26.18% T, with contents of A + T and G + C being 57.75% and 42.25%, respectively. [ABSTRACT FROM PUBLISHER]