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During a parasitological survey carried out between May and August 2022 in the River Nyando, Lake Victoria Basin, a single species of Rhabdochona Railliet, 1916 (Nematoda: Rhabdochonidae) was recorded from the intestine of the Rippon barbel, Labeobarbus altianalis (Boulenger, 1900) (Cyprinidae). Based on light microscopy (LM), scanning electron microscopy (SEM) and DNA analyses the parasite was identified as Rhabdochona (Rhabdochona) gendrei Campana-Rouget, 1961. Light microscopy, SEM and DNA studies on this rhabdochonid resulted in a detailed redescription of the adult male and female. The following additional taxonomic features are described in the male: 14 anterior prostomal teeth; 12 pairs of preanal papillae: 11 subventral and one lateral; six pairs of postanal papillae: five subventral and one lateral, with the latter pair at the level of first subventral pairs when counted from the cloacal aperture. For the female: 14 anterior prostomal teeth and the size and absence of superficial structures on fully mature (larvated) eggs dissected out of the nematode body. Specimens of R. gendrei were genetically distinct in the 28S rRNA and cytochrome c oxidase subunit 1 (cox 1) mitochondrial gene regions from known species of Rhabdochona. This is the first study that provides genetic data for a species of Rhabdochona from Africa, the first SEM of R. gendrei , and the first report of this parasite from Kenya. The molecular and SEM data reported herein provide a useful point of reference for future studies on Rhadochona in Africa. [Display omitted] • Redescription of Rhabdochona gendrei from Labeobarbus altianalis. • The first study providing genetic data for a species of Rhabdochona from Africa. • This is the first scanning electron microscopy study of R. gendrei. • First report of R. gendrei from Kenya. • Findings herein provide useful point of reference for future studies on Rhadochona. [ABSTRACT FROM AUTHOR]

In this study, a practical protocol for artificial reproduction was developed for the rudd, Scardinius erythrophthalmus , to help to produce this fish for aquaculture industries and also for restocking programs. For this purpose, the efficiency of different hormonal agents and their combinations for spawning induction of female breeders of rudd was evaluated. Ovulations were stimulated using different treatments as: two injections of Ovaprim (Ova), two injections of Ovopel (Ovo), a priming dose of Ovopel with a resolving dose of Ovaprim (Comb1), a priming dose of Ovaprim with a resolving dose of Ovopel (Comb2), and two injections of sterile 0.9% NaCl solution as a control group. During the study, ovulation success, egg developmental competence as well as the performance of the freshly hatched larvae were recorded. There was no ovulation in females from the control group. In hormone-treated groups, 84–100% of fish ovulated, but no differences were observed in ovulation success (P > 0.05). The shortest latency period in treated fish was recorded in the Ovo group (431.6 degree-hour, P < 0.05). The best results in terms of working fecundity (number of obtained eggs per fish), relative fecundity, fertilization success, hatching rate, and embryo survival up to the eyed stage were achieved in the Ova and Comb1 groups (P < 0.05). Moreover, better survival rates up to the absorbing yolk sac stage and the lowest abnormality of larvae were observed in Ova and Comb1 groups (P < 0.05). There was no significant difference in the incubation time among different groups (P > 0.05). The obtained results indicate that two injections of Ovaprim and/or a priming dose of Ovopel with a resolving dose of Ovaprim are suitable for the artificial reproduction of rudd female breeders. Due to the proper effects and ease of use, two injections of Ovaprim could be recommended for the production of this species for restocking or aquaculture programs. [ABSTRACT FROM AUTHOR]

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

Currently, the existence of Tor species is threatened with extinction and is listed on the IUCN red list due to overfishing, forest destruction, water pollution, fluctuations in water volume, and land conversion. This study aims to fully describe the differences in the osteocranium structure of four Tor species (T. tambroides , T. douronensis , T. tambra , and T. soro) in Indonesia. Visually, the genus Tor is identified by the presence of a lobe on the ventral side of the lower lip. T. tambroides has long and thick lobes, T. tambra has short lobes, T. douronensis has long and thin lobes, while T. soro has very short lobes. The results of the osteocranium structure analysis of four Tor species showed differences, including the occipital, lateral ethmoid, frontal, infraorbital, nasal, preethmoid, prootic, pterotic, vomer, lateral ethmoid processus, pterotic processus, and lateral processus bones, where the differences in the osteocranium structure include the size, number, and development of the bone. The results of the univariate analysis (analysis of variance) of 33 characters of biometric data showed that 20 characters were significantly different (P < 0.05) and the other 13 characters were not significantly different (P > 0.05). Furthermore, the results of multivariate analysis (principal component analysis) of 33 biometric data characters succeeded in discriminating four Tor species into four separate groups; however, T. tambroides and T. douronensis tended to be more closely related than the other two species. In conclusion, this study shows that osteocranium structure and biometric analysis have successfully authenticated four Tor species into four separate groups validly. [ABSTRACT FROM AUTHOR]

In cyprinids aquaculture, the implication of gonadotropin-releasing hormone analogues (GnRHa) in combination with a dopamine inhibitor has been suggested to induce spermiation. The study investigated the efficiency of Ovaprim (consists of 20 μg (D-Arg6, Pro9NEt)-sGnRH and 10 mg domperidone per mL) on spermiation in the common bream, Abramis brama. The males (n = 10 in each group) with a mean body weight of 863.2 ± 22.8 g were injected with 0.25 or 0.5 mL kg−1 Ovaprim at the spawning season. The control group was injected with physiological saline. To evaluate hormonal therapy, sperm production, motility and fertilizing ability were assessed together with some biochemical characteristics of seminal plasma. The hormonally treated groups produced more sperm in volume with higher total number of spermatozoa (P < 0.05). However, spermatozoa concentration and spermatocrit were lower in males treated with 0.5 mL kg−1 Ovaprim compared to the control group (P < 0.05). Duration of spermatozoa motility did not differ among groups, while percentage of motile spermatozoa was lower in the males treated with 0.5 mL kg−1 Ovaprim compared to the males in the control group or those treated with 0.25 mL kg−1 Ovaprim (P < 0.05). The 0.25 mL kg−1 Ovaprim treated group showed the highest osmotic pressure and cholesterol level and the lowest lactate dehydrogenase activity in the seminal plasma, which differed significantly from the 0.5 mL kg−1 treated group (P < 0.05). Ionic composition and pH of seminal plasma did not differ among groups. The highest fertilization and hatching rates were observed when the males treated with 0.25 mL kg−1 Ovaprim. However, differences in survival and malformations of larvae were not significant among groups. In general, the results of the present study suggest a higher efficiency of Ovaprim at 0.25 compared to 0.5 mL kg−1 to induce spermiation in common bream, which results in higher fertilization ability. This study provides novel information on developing controlled reproduction of common bream in aquaculture. • Spermiation of common bream was evaluated after induction with Ovaprim. • Injection of Ovaprim positively affected semen production and quality. • Better fertilization and hatching rates were achieved after using treated fish semen. • Neither ionic composition nor pH of semen was affected in hormonal-treated groups. • Ovaprim injection at 0.25 mL kg−1 can effectively induce spermiation in bream. [ABSTRACT FROM AUTHOR]

Short-term sperm storage is a straightforward and cost-effective method of managing logistics in large scale fish hatchery operations but may result in decline in sperm quality. For effective artificial reproduction of fish, use of an appropriate additive to optimize sperm storage conditions is essential. In this study, it was investigated the effect of purified seminal plasma transferrin (Tf) at 10 μg/ml on relevant parameters in common carp Cyprinus carpio sperm during short-term storage. We compared sperm motility and curvilinear velocity, adenosine triphosphate (ATP) content and DNA fragmentation of fresh spermatozoa to that stored for 24, 48, 72, and 144 h with or without Tf. The percentage of motile cells and the curvilinear velocity of spermatozoa in stored samples for 72 h with transferrin supplementation were greater compared to samples with no added protein. The ATP content in samples without added transferrin was reduced (P < 0.05) after 72 h of storage, in contrast to the levels observed in transferrin-supplemented sperm. A time-dependent increase in DNA fragmentation was observed. Significantly lower DNA damage, expressed as percent tail DNA (10.99 ± 1.28) and olive tail moment (0.54 ± 0.12), was recorded in Tf-supplemented samples stored for 48 h compared to that with no Tf. Hence, it is concluded that the beneficial effects of transferrin on common carp sperm could serve as an additional tool for developing and enhancing short-term sperm preservation procedures commonly used in aquaculture. • Treatment with Tf led to an improvement in sperm motility parameters after 72 h. • Tf-supplemented sperm had higher ATP content than those without Tf. • After 48 h, Tf-supplemented samples showed less DNA damage than those without Tf. • Tf addition shows promise for short-term in vitro sperm storage. [ABSTRACT FROM AUTHOR]

Assamese kingfish (Cyprinion semiplotum) belonging to the subfamily Barbinae is an important food as well as aquarium fish having identified pharmacological benefits. The species has a complex taxonomic history and its phylogenetic position remains uncertain. Molecular data employed in earlier phylogenetic studies was inadequate for its phylogenetic placement. Therefore, we characterized 16,671 bp long complete mitogenome of C. semiplotum using next-generation sequencing. The mitogenome encodes the typical set of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and two non-coding regions. Its gene organization, distribution pattern, nucleotide composition, tRNA secondary structure and codon usage was similar to other Cyprinid mitogenomes. However, a distinctive 90 bp insertion was found in 3′ periphery of the AT-rich control region. This can be a tool for identification of the species at the population level. Further, we reconstructed the most comprehensive phylogenetic trees of Cyprinidae based on complete mitogenome. In the resulting phylogenetic trees, C. semiplotum clustered tightly with other Barbinae species and exhibited a sister relationship with the species of the genera Aulopye , Barbus , Luciobarbus and Capoeta. The results presented herein will support future investigations on molecular taxonomy, population genetics, evolution and molecular phylogeny of C. semiplotum and its relatives. [ABSTRACT FROM AUTHOR]

Cyprinidae is the predominant and most diverse taxonomic group of freshwater fishes, exhibiting enormous diversity in shape, size and biology. The morphological diversity of Indian Cyprinids especially the Gangetic Cyprinids is largely unquantified. Geometric morphometrics (GM) approach is an efficient tool to quantify overall body shape variations and has wide application in taxonomic, evolutionary and ecological studies. In this study, digital photographs of 47 Cyprinid fish species from Ganga River were used to measure geometric body shape so as to evaluate interspecific morphometric relationships. Combined results of principal component analysis (PCA), canonical variate analysis (CVA) and Cluster analysis (CA) revealed interspecific differences in Cyprinid fishes. Phenogram showed that all the species of different genus like Barilius , Garra , Labeo , Pethia , Schizothorax and Tor are clustered together in their respective group. This indicates that species of respective genus share common phenotypic traits and there is evolutionary relatedness among them. The present study showcases the efficient use of digital images and strongly supports the application of cost–effective GM method in discriminating distinct groups and representing the morphological relationships between species of Cyprinid fishes. Overall, we suggest that the body shape disparity and proximity among groups can therefore be used as an effective approach in rapid diagnosis of a species and understanding evolutionary relationships between species. [ABSTRACT FROM AUTHOR]

This study presents the first complete mitochondrial genome (mitogenome) of Caecobarbus geertsii , the Congo blind barb, a cave-dwelling, CITES-protected, cyprinid fish endemic to the Lower Congo basin (DRC). The length of the circular mitogenome is 16,565 base pairs. The 13 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes are similar in position and direction to those of other members of the family Cyprinidae. Phylogenetic analyses including 28 complete mitogenomes from representatives of the subfamily Smiliogastrinae (Cyprinidae), showed that Caecobarbus was nested within a clade including representatives of the genus Enteromius. The data presented in this study provide information on the molecular identification and classification of this threatened species. The results further suggest the need for a taxonomic revision of the genus Enteromius. [ABSTRACT FROM AUTHOR]

• The pattern of host–parasite coevolution was revealed comparing phylogenies. • Host switching plays an important role in coevolution of ectoparasitic monogeneans. • Monogeneans represent a useful additional tool for investigating historical and more contemporary contacts of their hosts. • The morphology of monogenean haptoral elements is helpful for resolving uncertain relationships between recent lineages. The diversification of Mediterranean fish appears to be far more complex than could be explained by a single dispersion model. Cyprinids represent one of the most species-rich groups of freshwater fishes living in this region. The current distribution of several highly divergent cyprinid taxa is most likely the result of multiple dispersion events. Cyprinid fish serve as hosts for the highly diversified and host-specific monogenean parasites of the genus Dactylogyrus. On the assumption that the distribution of Dactylogyrus spp. reflects the biogeography and evolutionary history of their hosts, we used these parasites as an additional tool to shed new light on the evolutionary history of peri-Mediterranean cyprinids of the subfamily Barbinae. The degree of congruence between host and parasite phylogenies was investigated using 29 Dactylogyrus spp. and 34 Barbinae hosts belonging to the genera Aulopyge, Barbus and Luciobarbus. We showed that the morphological adaptation of Dactylogyrus (i.e. of the ventral bar, representing the most variable morphological character of the attachment organ) is linked with parasite phylogeny. By applying distance-based and event-based cophylogenetic approaches, we revealed a significant global coevolutionary signal. A total of 62% of individual host–parasite links contributed significantly to the coevolutionary structure evidenced between hosts of Barbus spp. and Iberian Luciobarbus spp., and their host-specific Dactylogyrus spp. The host switching of parasites was revealed as the most important coevolutionary event in the Dactylogyrus -Barbinae system in the peri-Mediterranean region. Cophylogenetic analyses and the mapping of the morphological character of the parasite attachment organ onto the phylogeny of Dactylogyrus indicate that endemic southern European Dactylogyrus spp. parasitizing cyprinids of Barbinae have multiple origins. We suggest that continental bridges connecting southern Europe and North Africa played a crucial role in the dispersion of cyprinids, affecting the distribution of their host-specific gill parasites. [ABSTRACT FROM AUTHOR]

A species introduced outside of its native range will likely encounter unusual abiotic and biotic conditions,and may exhibit phenotypic traits that may facilitate survival and persistance. Phenotypic plasticity drives non-native species' development of adaptive traits in the new environment, increases their fitness, and as a result, contributes to invasion success. In this study, we examined inter and intraspecific phenotypic variation (body size and shape) for an invasive (Carassius gibelio) and introduced (Cyprinus carpio) cyprinid fish species (Teleostei: Cyprinidae) in the Düden Stream, Turkey, which is a small-scale river system. We hypothesized that interspecific phenotypic variation correlates with fish-specific variables and river site. We further hypothesized that these two species may exhibit similar phenotypic variation patterns between populations. The MANCOVA revealed that species-specific traits, river site, had significant effects on body shape variation and size along the stream. The differences in the shape of the head, the central portion of the body, and fins in both species most probably reflected differences in the swimming and feeding of the fish, possibly to avoid interspecies competition. The intraspecific phenotypic variation observed in both species may indicate rapid local adaptation, triggered by multiple founding event, or/and phenotypic plasticity. [ABSTRACT FROM AUTHOR]

The common tench is an important thermophilic freshwater fish used for aquaculture diversification. This species is farmed in ponds as well as caught in the wild in many European and China. Artificial reproduction under controlled conditions is one of the most important part of modern aquaculture. In this study, two experiments were conducted in which the influence of hormonal agents (Ovopel and Ovaprim - experiment I) and the origin of the spawning stock (wild and pond-cultured - experiment II) on the success of reproduction in terms of ovulation rate (%), latency time (h), pseudo-gonadosomatic index (PGSI, %), hatching rate (%), abnormal larvae rate (%), and spawning efficiency coefficient (Se) were examined. While the wild fish could not reproduce in the absence of hormonal treatment with 0 % ovulation rate. In all tested hormonal treatment allowed to obtain high-quality eggs with hatching rates of over 83 %. Significant differences in latency time were observed among groups from different origins, such as differences in ovulation rate (79 % vs. 90 %, for pond-cultured and wild fish, respectively), PGSI (8.2 vs. 8.9), and hatching rate (63.8 % vs. 84.3 %), which showed significantly better quality in fish from the wild than those from pond culture. This means that when spawners of common tench of various origins are available, it is better to choose spawners from natural waters for artificial reproduction. • All tested combinations of spawning agents were successful in tench artificial reproduction. • Differences in the reproduction efficiency of wild and pond-cultured forms of tench were found. • The reproductive efficiency of wild fish was higher than pond-cultured fish. [ABSTRACT FROM AUTHOR]

Based on morphology and ITS sequence data, we identify and supplementally describe Gyrodactylus pseudorasborae Ondračková, Seifertová & Tkachenko, 2023 on the fins of topmouth gudgeon (Pseudoraspora parva) from freshwaters of southern China. The highest similarity (99.57% and 99.47%) to G. pseudorasborae suggested they were the same species. Prevalence and mean intensity were 45% and 2.3, respectively. The gyrodactylid species morphologically resembled G. pseudorasborae recorded from the same host species P. parva in Czech Republic, Ukraine, and Central China. But there were slight morphological differences in the shape and size of the marginal hook. Comparisons of marginal hook sickles of various Gyrodactylus species suggested that G. pseudorasborae and G. parvae were members of the G. wageneri -group. A molecular phylogeny of G. pseudorasborae with related species is presented and discussed within the context of the mechanism of local evolution of these sister species. [Display omitted] • Gyrodactylus pseudorasborae was supplementally described in South China. • Haptoral hard parts of this parasite are slightly smaller than those in Europe. • G. pseudorasborae from South China was a member of the G. wageneri-group. • Equilibrium life history strategy was supported with smaller host in native regions. [ABSTRACT FROM AUTHOR]

Predicting future changes in habitat-associated species traits is an important step in understanding the ecological and evolutionary consequences of environmental change. However, models projecting phenotypic responses to future climate change typically assume populations will respond similarly across the range of a species, while local adaptation and spatial variation in environmental changes are rarely considered. In this study, among-population phenotypic variability was coupled with geographic variation in anticipated hydrologic changes to examine patterns of population-level phenotypic changes expected under future climatic change. To estimate phenotypic responses to watershed hydrology, phenotype-environment associations between body shape and contemporary streamflow were quantified among populations of six species of fishes (Cyprinidae). Future streamflow estimates (2070–2099) were then used to project body shapes within populations, assuming the same phenotype-environment relationships. All species exhibited significant associations between body shape and contemporary streamflow discharge and variability. However, these relationships were not consistent, even among species occupying similar vertical positions in the water column. When these phenotype-environment relationships were projected into future streamflow conditions, populations are not expected to respond uniformly across the species' ranges, and all but one species exhibited projected morphologies outside of the current range of morphological variation. These findings suggest local adaptation and spatial heterogeneity in environmental changes interact to influence variation in the degree of expected phenotypic responses to climate change at both the species and population level. Unlabelled Image • Stream discharge and variability drive intraspecific differences in fish morphology. • Future morphology (2070–2099) was projected from morphology-hydrology associations. • Future climate-induced hydrologic changes result in variable projected phenotypes. • Changes in environmental suitability will vary at the population and species levels. [ABSTRACT FROM AUTHOR]

Abstract Freshwater contamination with mining waste can result with high concentrations of toxic metals in the water and in fish organs. In North-Eastern Macedonia, several rivers (e.g., Zletovska, Kriva) are exposed to acid mine drainage from active Pb/Zn mines. Previous studies confirmed high concentrations of dissolved metals in their water. This study was performed in liver and gills of Vardar chub (Squalius vardarensis Karaman, 1928) from three Macedonian rivers (Bregalnica, Kriva and Zletovska) in spring and autumn 2012. The aim was to establish if increased exposure to certain metals have resulted with their increased bioaccumulation. The concentrations of 19 elements were measured in cytosolic tissue fractions, to obtain information on metabolically available metal species. The following ranges of cytosolic concentrations of highly toxic elements were measured in the Vardar chub liver (in μg/L): Cd, 1.18–184; Cs, 0.25–25.4; Tl, 0.02–5.80; Pb, 0.70–61.1. Their ranges measured in the gills (in μg/L) were the following: Cd, 0.24–59.2; Cs, 0.39–24.4; Tl, 0.01–1.00; Pb, 0.65–87.2. Although the water of the mining impacted Zletovska River was highly contaminated with several essential metals, especially with Mn and Zn, the majority of essential elements (Na, K, Ca, Mg, Co, Cu, Fe, Mn, Mo, and Zn) did not reflect the exposure level. In contrast, seven nonessential elements reflected the level of exposure in the water. Significantly increased hepatic and gill concentrations of Cs, Rb, Sr, and Tl were detected in Vardar chub from the Zletovska River compared to the other two rivers, of Cd and Pb in the Zletovska and Kriva River compared to Bregalnica, and of V in the Bregalnica River compared to Zletovska and Kriva rivers. Observed significant metal bioaccumulation, in particular of highly toxic elements, as a consequence of exposure to water contaminated with mining waste points to necessity of intensified supervision of mining impacted rivers. Graphical abstract Image 100 Highlights • Study of metal pollution of mining impacted rivers of North-Eastern Macedonia. • Analysis of bioaccumulation of 19 elements in gills and liver of Vardar chub. • Essential elements Na, K, Ca, Mg, Co, Cu, Fe, Mn, Mo, Zn kept within narrow ranges. • Toxic elements Cd, Cs, Pb, Rb, Sr, Tl, and V reflected the exposure level. • Pollution of Zletovska River resulted in high toxic metal levels in chub organs. Mining waste presents serious threat and hazard for the health of aquatic animals because it causes high bioaccumulation of very toxic metals, such as Cd, Pb, Cs and Tl, into their organs. [ABSTRACT FROM AUTHOR]

Abstract This study focused on the artificial reproduction of common dace Leuciscus leuciscus (L.) outside the reproductive season. The results indicate there is the possibility of initiating the reproducion in individuals of this before the natural spawning season. There could be induction of spermiation by altering the environmental conditions. For females, hormonal injections were necessary for induction of final oocyte maturation and ovulation. Generally, there were high percentages of spermiation (100%) and ovulation (87%–100%) as well as low mortality (0%–11% and 7%–13% for males and females, respectively) among the induced spawners. The greatest embryo survival occurred when Ovaprim (84.4%) or hCG (89.6%) was administered, although the latency time using hCG was at least twice as long compared to when other spawning agents were used (84–92 hrs and 30–44 hrs). The results from present study could be applicable for optimization of breeding stock numbers in aquaculture enterprises and in providing insights for conservation of L. leuciscus endangered populations. [ABSTRACT FROM AUTHOR]

Abstract Stream salinization is a great environmental hazard being aggravated by anthropogenic disturbances. Harmful conditions, as increasing salinity in freshwater systems, may negatively affect river fish fauna and possibly influence fish behaviour, such as boldness and/or cerebral lateralization. Salinity has been proven to affect behavioural expression, despite the tolerance of some species. It is thus relevant to study these behaviours, as the salinity exposure effects could represent greater environmental consequences. The impact of salinity stress was evaluated by exposing Iberian barbels, Luciobarbus bocagei (Steindachner, 1864) (Cypriniformes, Cyprinidae), to three levels of salinity (0.9, 9 and 19 mS/cm, using NaCl) and by conducting boldness and lateralization experiments, regarding population trends. Results show that, with increased salinity, fish diverged to the extremes of the shy-bold gradient, the population was slightly lateralized to the left, and seemed to become more lateralized with increasing salinity. However, there were no statistical differences between the treatments. Fish living in a Mediterranean climate are especially resilient to various stressors, which may confer them additional tolerance, and in this case, acute punctual exposure to increased salinity may not be detrimental for behaviour maintenance. We encourage the expansion of the research to different freshwater fish species that would help to recognise salinity thresholds and use them to implement effective conservation measures and appropriate ecological restoration actions for these sensible systems. Graphical abstract Unlabelled Image Highlights • We evaluate the effects of salinity on freshwater fish behaviour. • Fish seem to become bolder and shyer with higher levels of salinity. • Fish behaviour was not significantly affected by the salinity stress. • With higher salinities fish seem to become more lateralized. • Population lateralization left trend was maintained throughout treatments. [ABSTRACT FROM AUTHOR]

Highlights • CyhV-3 glycoproteins pORF25, pORF65, pORF148, pORF149 are dispensable for replication. • pORF25 and pORF149 are relevant for efficient virus entry and cell-to-cell spread. • The adverse effect of ORF149 deletion is compensated by additional ORF148 deletion. • Deletion of ORF148 and/or ORF149 does not significantly reduce virulence of CyHV-3. • Deletion of ORF148 and/or ORF149 does not affect protective efficacy of CyHV-3. Abstract Cyprinid herpesvirus 3 (CyHV-3) or koi herpesvirus is a global pathogen causing mass mortality in koi and common carp, against which improved vaccines are urgently needed. In this study we investigated the role of four nonessential, but immunogenic envelope glycoproteins encoded by members of the ORF25 gene family (ORF25, ORF65, ORF148 and ORF149) during CyHV-3 replication. Single deletion of ORF65 did not affect in vitro replication, and deletion of ORF148 even slightly enhanced virus growth on common carp brain (CCB) cells. Deletions of ORF25 or ORF149 led to reduced plaque sizes and virus titers, which was due to delayed entry into host cells. An ORF148/ORF149 double deletion mutant exhibited wild-type like growth indicating opposing functions of the two proteins. Electron microscopy of CCB cells infected with either mutant did not indicate any effects on virion formation and maturation in nucleus or cytoplasm, nor on release of enveloped particles. The ORF148, ORF149 and double deletion mutants were also tested in animal experiments using juvenile carp, and proved to be insufficiently attenuated for use as live virus vaccines. However, surviving fish were protected against challenge with wild-type CyHV-3, demonstrating that these antibody inducing proteins are dispensable for an efficient immune response in vivo. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydropeaking events and deflector use were investigated for the Iberian barbel. • Higher velocities (≈0.6 m.s−1) and flow ratios (5.7 and 8.6) promoted deflector use. • Individual deflector use and swimming activity predominated in the single-step event. • In the presence of deflectors peak repetition triggered a glucose response. • Movement behaviour generally decreased during the second peak with deflectors. Abstract Fish responses to hydropeaking may range from sub-organismal adjustments to key life-event changes. It is currently difficult to quantify these responses and to assess the potential of artificial refuges accordingly. To address this problem, two experimental trials were conducted in an indoor flume. In the first, two hydropeaking events were tested in the presence of deflectors as flow refuges. In the second, the presence and absence of deflectors was tested for the same hydropeaking event. A multidisciplinary approach combined physiological and movement behaviour responses of Iberian barbel (Luciobarbus bocagei) with hydrodynamic models. These were used as a complementary tool to explain the fish responses. In the first experiment, no evident physiological adjustments occurred. However, individual refuge use and swimming activity were higher in the single-step event where velocities above 0.6 m.s−1 were observed. In the second experiment, the levels of glucose were the highest in the repeated single-step event with deflectors, whereas in their absence no visible changes were observed. The sequence of discharges affected the frequency of individual sprints and group drifts, particularly evident with deflectors. Additionally, the deflector use increased in the first peak in opposition to the second. Overall, the fish responses were indicative that the low velocity areas (<0.1 m.s−1) existing behind the deflectors were favourable under hydropeaking conditions. However, the flow complexity resulting from the presence of deflectors impaired their ability to successfully find them. The integrated approach used in this study provided novel insight considering the responses of cyprinids to hydropeaking in the presence and absence of deflectors as a mitigation measure. This study emphasized the importance of characterizing the hydrodynamic conditions due to hydropeaking, particularly after including the artificial refuges. [ABSTRACT FROM AUTHOR]

Abstract The positive relationship between locomotion performance and survival under predation has long been suggested yet seldom demonstrated with direct evidence. We investigate the effects of predator exposure on locomotion capacity (both fast-start escape and critical swimming performance), survival under predation and the relationships between these factors in juvenile Chinese bream (Parabramis pekinensis). This study aims to test whether there is a positive relationship between the above factors and whether such relationships are context dependent (i.e., with or without 20 d of predator exposure). We found that predator-exposed Chinese bream showed higher rates of survival under predation and improved fast-start swimming performance compared with individuals not exposed to predation. At individual level, no relationship was found between survival and any locomotion performance component in the no-predator group, but mean fast-start swimming speed, maneuverability and responsiveness were all positively related to survival in the predator group after 20 d of exposure. This finding indicates that the recognition of and vigilance for predators achieved through predation experience can be crucial preconditions for prey to employ the fast-start escape response, especially to escape ambush predators. Furthermore, a tradeoff was observed between the critical and fast-start swimming performances in the predator group, but not in the no-predator group, which may have been due to the intensified competition throughout the entire locomotion-support system (e.g., energy, proportions of slow- and fast-twitch muscle fibers) between critical and fast-start swimming because the increased demand for fast-start escape capacity constrains (or compromises) critical swimming performance under the threat of predation. Graphical abstract Unlabelled Image Highlights • Predation experience underlies the relationship between fast-start escape capability and survival in a cyprinid fish. [ABSTRACT FROM AUTHOR]

Abstract This study aimed to investigate the effects of dietary non-protein energy adjustments on the mitochondrial biosynthesis and function of juvenile Megalobrama amblycephala. Fish (average weight: 37.98 ± 0.07 g) were fed eight diets containing two dietary carbohydrate levels (30% and 43%) and four lipid sources (fish oil, soybean oil, palm oil and the mixed oil) for 11 weeks. Liver mitochondrial respiratory chain complex V activity and ATP (adenosine triphosphate) content both increased significantly with increasing dietary carbohydrate levels, whereas the opposite was true for the AMP (adenosine 5′-monophosphate)/ATP ratio, hepatic transcripts of AMP-activated protein kinase α1 (AMPKα1), AMPKα2, peroxisome proliferators γ-activated receptor coativator-1α (PGC-1α), NADH dehydrogenase 1 and cytochrome c oxidase 1 (COX1) as well as the activities of Na+-K+-ATPase, succinate dehydrogenase (SDH), citrate synthase (CS) and mitochondrial respiratory chain complex I, III and IV. Additionally, hepatic ATP content, the transcripts of AMPKα, COX1 and ATP6 and the activities of Na+-K+-ATPase, SDH, CS and mitochondrial respiratory chain complex III were all significantly affected by lipid sources. Furthermore, an interaction between dietary carbohydrate levels and lipid sources was also observed in the activities of liver mitochondrial Na+-K+-ATPase and respiratory chain complex III as well as the transcripts of ATP6 and PGC-1α. Overall, these findings suggested that dietary carbohydrate levels and lipid sources remarkably affected the mitochondrial biosynthesis and function of M. amblycephala. A diet containing 30% carbohydrate and FO could boost its mitochondrial biosynthesis, while that of 30% carbohydrate and SO could enhance the mitochondrial function. [ABSTRACT FROM AUTHOR]

The increased consumption of plastics worldwide, has led to the emergence of nanoplastics as important environmental pollutants. Despite the presence of nanoplastics in aquatic environments, their effects on ecosystems remain largely unexplored due to the analysis complexity. This study investigated the organ accumulation and toxic effects of 50 nm polystyrene nanoplastics (PS-NPs) in Zacco platypus (Z. platypus ; also known as pale chub fish) using pyrolyzer-gas chromatography-mass spectrometry (Pyr-GC/MS). PS-NPs accumulated in Z. platypus ' brain, digestive tract, branchia, and liver, causing changes at cellular level. Over a 14-day exposure, the accumulated PS-NPs led to observable changes in fish behavior (e.g., Total traveled distance and maximum velocity). In addition, the oxidative stress in each organ of Z. platypus increased as the exposure concentration of PS-NPs increased. This study shows that accumulation of nanoplastics in fish, resulting in behavioral changes and biochemical toxicity. As the pattern of change magnifies with exposure time and concentration, from a long-term perspective, the influence of nanoplastics on aquatic ecosystems become evident. This underscores the urgency for continuous research into the potential risks of nanoplastics in aquatic ecosystems. [Display omitted] • Accumulation of Polystyrene nanoplastics (PS-NPs) in Zacco platypus tissue. • Zacco platypus exposed to PS-NPs exhibited histopathological changes. • PS-NPs exposure induced behavioral changes and oxidative stress in Zacco platypus. [ABSTRACT FROM AUTHOR]

[Display omitted] • We develop new multimetric index and diagnostic tool to assess small standing waters. • Ten environmental predictors allow to define metric reference values per site. • The BECOME index discriminates 94% of impaired sites whatever pressure types. • The index is sensitive to 13 land use-, hydromorphology- and biotic-based pressures. • The BECOME d diagnostic tool helps to identify major sources of SSW alteration. Small shallow lakes and ponds (SSWs) have high conservation value and support numerous ecosystem services. However, these small ecosystems face many threats, including eutrophication and internal biotic pressures like Cyprinidae or exotic bioturbators crayfish, which tend to shift biodiverse SSWs to a turbid state dominated by phytoplankton unfitted to numerous usages, and compromise the effectiveness of their restoration. The ecological quality of SSWs and the efficiency of their management still remain poorly evaluated because of the lack of adapted tools. To fill this gap, we propose a new multimetric index (BECOME) and a diagnostic tool (BECOMEd) both based on macrophyte and invertebrate communities. BECOME exhibits a high sensitivity to the impact of surrounding crops, urbanization and fertilized meadows, morphological alterations, and various internal biotic sources of alterations, in a wide variety of geological and climatic contexts. BECOME is especially innovative, because taking into account internal biotic sources of pressures neglected by most of the existing biological WFD-compliant indices for European lakes and ponds, despite their importance in SSW threats. BECOMEd allows to identify the major alteration sources and estimates their relative contribution to SSW degradation, helping managers to prioritize actions or to evaluate their effectiveness. The statistical design applied for the index construction has been fitted to develop biological index for ecosystems influenced by a wide amplitude of numerous environmental conditions. This design could be easily applied elsewhere in the world, for SSWs but also for other types of ecosystems. [ABSTRACT FROM AUTHOR]

Yellow rasbora (Rasbora lateristriata) exhibits potential as a novel animal model for research purposes. Nevertheless, the process of embryonic development of this fish species remains inadequately comprehended. This study aimed to characterize the embryonic development stages of yellow rasbora. The embryonic development was documented using time-lapse technique to observe the following parameters: the embryonic cleavage, the blastomere, the epiboly area, and the somites. Heart development and morphological changes were also observed, including the number of heartbeats at 24, 30, 48 h post-fertilization. The cartilage structure in the cranium of larvae aged 1 to 3 days post-fertilization were observed as well. Alizarin red and Alcian blue staining were used to stain bone and cartilage structures. The results of this study describe the important stages of embryogenesis in yellow rasbora, including the zygote, cleavage, blastula, gastrula, segmentation, pharyngula, and hatching stages. The first contraction of the heart muscle was observed at 20 h post-fertilization, with cardiac tube looping occurred at 24–30 h post-fertilization. The cranium cartilage was formed 2 days post-fertilization and completed at 3 days post-fertilization. In conclusion, this study provided a comprehensive overview of the developmental stages of yellow rasbora embryos. [ABSTRACT FROM AUTHOR]

Abstract The objective of this present study is to determine the optimum concentration for glutathione in the cryopreservation of seurukan fish (Osteochilus vittatus) spermatozoa. A completely randomized design (CRD) was used with 6 treatments and 3 replications. The Seurukan fish sperm was diluted in extender with a ratio of 1:20 (sperm: extender), then glutathione was added at a concentration of 0, 10, 20, 30, 40 and 50 mg L−1. Next, the sperm thawed at 39–40 °C for 3 min and mixed with 100 eggs which were randomly selected. The success of the fertilized egg was observed 6 h after fertilization, while the hatching rate was examined 60 h after fertilization. The ANOVA test showed that the addition of glutathione significant affected the sperms motility, fertility and hatching rate of seurukan fish Osteochilus vittatus eggs (P < 0.05). By segregation the fresh sperm, a higher sperm motility rate was recorded with an addition of 30 mgL−1 of glutathione (63.00 ± 5.89), however, this value was not significantly different from using concentration of 10 and 20 mg L−1. A higher fertilization rate was produced using glutathione concentration of 50 mg L−1 (51.33 ± 17.01); however, it was also not significantly different from the concentration of 20, 30 and 40 mgL−1. In addition, a higher hatching rate was also recorded using glutathione concentration of 50 mg L−1 (40.33 ± 12.89), this value was not significantly different from using 40 mgL−1 glutathione. Hence, a conclusion was drawn that the optimum concentration of glutathione is 40 mg L−1 of diluent. [ABSTRACT FROM AUTHOR]

Abstract Vicariance and/or long-distance dispersal shape the distribution patterns of many extant taxa, and orogenesis and/or climate fluctuations are key factors that drive the events of vicariance and/or dispersal. In this study, we yielded biogeographical inferences from Bayesian binary MCMC (BBM) analysis to explore the potential colonization histories of Opsariichthys bidens in China and to identify potential factors responsible for the colonization histories. Many vicariance and dispersal events were identified. The results suggested that O. bidens seemed to have originated from the Yangtze River and/or the Pearl River and experienced a Yangtze River–Pearl River split at 7.04 million years ago (Ma). BBM analysis revealed that the Pearl River populations had undergone expansions to the Hainan drainages, the Lancangjiang River (upper Mekong) and the Nanpanjiang River (upper branch of the Pearl River) at 0.74 Ma. Meanwhile, the Yangtze River populations expanded to the northeastern drainages during the Early Pleistocene. Subsequently, the northeastern drainages dispersed to the Yellow River during the Middle Pleistocene. More recently, the northeastern drainage populations also dispersed to the Huaihe River and back to the Yangtze River. A portion of the Pearl River populations originated from the Yangtze River dispersed to the Jiulongjiang River during the Middle Pleistocene. These time scales fit well with the uplift of the Qinghai-Tibet Plateau and Pleistocene glacial cycles, indicating the two factors played vital roles in shaping the colonization histories of O. bidens. Highlights • We used BBM analysis to probe the colonization histories of Opsariichthys bidens. • Opsariichthys bidens underwent many vicariance and dispersal events. • Orogenesis and glaciations shaped the colonization histories of Opsariichthys bidens. [ABSTRACT FROM AUTHOR]

Triploid hybrid (3n = 150) of red crucian carp (♀, 2n = 100) and allotetraploid (♂, 4n = 200) display improved disease resistance and stress resistance than their parents. In order to elucidate their innate immune mechanisms, three novel cell lines from the caudal fin of red crucian carp, triploid hybrid and allotetraploid (named 2nFC, 3nFC and 4nFC accordingly) were established and characterized respectively. 2nFC, 3nFC and 4nFC showed fibroblast-like morphology and characteristics. They have been subcultured for more than 100 passages since the initial primary culture. Viral infection experiments showed that 2nFC, 3nFC and 4nFC were susceptible to spring viraemia of carp virus (SVCV) infection. Intriguingly, 3nFC performed the stronger resistance ability against SVCV than 2nFC and 4nFC, which indicated that 2nFC, 3nFC and 4nFC might be used as the suitable in vitro models for exploring and analyzing the differences among these three cyprinid fishes in antiviral innate immune mechanisms. Based on this, we analyzed the transcriptome profile of 2nFC, 3nFC and 4nFC in the context of SVCV infection. The KEGG enrichment analysis showed that the differentially expressed genes (DEGs) were primarily enriched to immune-related signaling pathways. However, some signaling pathways against viral infection were activated remarkably in 2nFC and 3nFC but not in 4nFC. Overall, the establishment of 2nFC, 3nFC and 4nFC provided us a suitable platform to elucidate the innate immunity of fishes with different ploidy and clear genetic relationship. [ABSTRACT FROM AUTHOR]

Highlights • Horizontal and vertical wedge-wire screens induced different hydrodynamics. • A vertical bar configuration created higher sweeping flow toward the bypass. • Chub avoidance to the screens was high resulting in low guidance overall. • A horizontal bar configuration under low discharge performed best. Abstract Physical screens are commonly installed to prevent downstream moving fish from entering dangerous areas (e.g. intakes to hydropower turbines, irrigation canals, and fish farms), and divert them to preferred alternative routes (e.g. bypass systems). In northern temperate regions, assessments of the functioning of screens have largely focused on diadromous species (e.g. salmon and eel), while ignoring those with other life history characteristics. Recent developments in physical screens include the usage of horizontally aligned bars as opposed to traditional vertical ones, but a direct comparison in terms of guidance remains untested. To address this and aid in the development of successful screens for the wider fish community, this study compared the efficacy of wedge-wire screens with horizontally and vertically oriented bars to block and divert downstream moving groups of five chub (Squalius cephalus) to a bypass channel installed in a recirculating flume under two discharge regimes. Hydrodynamics differed between horizontal and vertical screens under both flows; the vertical configuration created a higher velocity gradient towards the bypass. Total guidance (the number of bypass entries as a percentage of the number of approaches) was generally low (mean = 17.3% for all treatments), the highest being recorded for the horizontal screen under low discharge (25.3%). Rejections and holding station events, both proxies for fish exhibiting avoidance of the hydrodynamic conditions created by the screen, were lowest under this treatment. Horizontal performed better than vertical screens in guiding fish to the bypass under low but not high discharge. The results confirm that screen functioning is dependent on hydrodynamic conditions as well as the fish's behavioural response. [ABSTRACT FROM AUTHOR]

Highlights • Cyprinid herpesvirus 2 causes great damage to crucian carp aquaculture. • A CyHV-2 ORF92 protein fragment was used as antigen to raise monoclonal antibodies. • mAb-1B7 detected CyHV-2 in infected Ryukin goldfish fin cells and crucian carp tissues. • mAb-1B7 can be used for western blotting and immunofluorescence detection of CyHV-2. Abstract Cyprinid herpesvirus 2 (CyHV-2) infection is a recently discovered viral disease of farmed silver crucian carp (Carassius auratus gibelio) in mainland China that has resulted in massive fish mortality and appears to be spreading cross the world. Various detection methods based on nucleic acids have been developed, but effective immunological diagnostic method has not been reported for CyHV-2. In this study, recombinant ORF92 protein was used as a capture antigen to identify cells and tissues infected with CyHV-2 by immunological methods. Firstly, the open reading frame of CyHV-2 ORF92 was cloned into the PGEX-4T-3 vector and expressed in Escherichia coli. Purified recombinant ORF92 protein was then used as an antigen to prepare monoclonal antibodies, and an efficient hybridoma cell line was selected by dot-blot assay. The resulting mAb-1B7 was applied to detect CyHV-2 in infected Ryukin goldfish fin (RyuF-2) cells and fish tissues by western blotting and immunofluorescence assays. The monoclonal antibody could specifically identify CyHV-2 in infected RyuF-2 cells and gill, kidney, and spleen tissues, suggesting it could be applied for CyHV-2 detection in crucian carp. [ABSTRACT FROM AUTHOR]

Highlights • A new cell line (GiCF) from the caudal fin of Carassius auratus gibelio was established. • GiCF was susceptible to infection with CyHV-2 isolated from diseased C. a. gibelio. • CyHV-2 induced apoptosis in GiCF cells. • Induction of apoptosis in GiCF cells by CyHV-2 infection might depend on caspases activations. Abstract Herpesviral haematopoietic necrosis induced by cyprinid herpesvirus 2 (CyHV-2) in Carassius auratus gibelio has caused huge economic losses in aquaculture. To better characterize this pathogen at molecular and cellular levels, it is necessary to study its pathogenesis in a sustainable cell line. In this study, a new cell line (GiCF) from the caudal fin of Carassius auratus gibelio (C. a. gibelio) was established and characterised. Typical cytopathic effect represented by characteristic morphological changes was induced in the cells at the 7th day post infection with CyHV-2, which was isolated from diseased C. a. gibeli. The susceptibility of GiCF to CyHV-2 was further demonstrated by the presence of viral assembling factory in the cytoplasm unveiled by transmission electron microscopy, and viral protein synthesis through immunofluorescence and Western blot assays. Sustainable propagation of CyHV-2 in GiCF had been demonstrated by virus infection and titration assays in a consecutive manner. The virus titer reached 104.9±0.22 TCID 50 /ml, and infectious CyHV-2 was produced from the GiCF cells over 30 subcultures from the established cell lines. In addition, apoptosis was observed in the GiCF cells upon CyHV-2 infection by DAPI staining, TUNEL and Annexin V staining, and quantitative expression patterns of caspase genes suggested that caspase activation might involve in CyHV-2 induced apoptosis. In summary, a new cell line, GiCF, susceptible to CyHV-2 infection was established from caudal fin tissue of C. a. gibelio , and it should serve as an ideal infection platform to characterize CyHV-2 and its pathogenic effect including apoptosis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Both fishway types showed a similar good performance for barbel passage. • Fish length had a direct relationship on transit time. • Ecology and engineering should go hand in hand to improve mitigation efforts. Abstract When engineers and ecologists face a fishway design, many issues need to be considered, the type of fishway being the first and foremost. It is an especially complex issue in areas with species whose migratory and swimming behavior are as yet poorly known as Mediterranean barbels. The present study focuses on the fish passage of two of the most common types of technical fishways: Vertical Slot (VS), and Submerged Notch with Bottom Orifice (SNBO). Both types were studied and compared in terms of ascent ability (as the success rate and transit time) and motivation (as the proportion of attempts and attempt rate), with Iberian barbel (Luciobarbus bocagei) as the target species. Ascent ability in VS and SNBO were similar. More than 90% of fish ascended the fishways successfully and the median transit time to ascend a total water height of 2.25 m was less than 23 min. Fish length had an effect on ascent time, with the biggest ones being faster. Motivation was greater for VS, although not seeming to have a relevant influence in the passage. These results support the use of VS and SNBO in areas with Iberian barbel and provide new data of fishways performance helping ecologists and engineers with their decision making, mainly in Mediterranean areas with similar habitats and species. [ABSTRACT FROM AUTHOR]

The acclimation rate of physiological functions that bear fitness costs under a changing environment is key to making predictions for fish, yet this has seldom been investigated. This study aimed to test whether there were different responses when different physiological functions reached steady states and to determine possible relationships with metabolic constraints during temperature changes in fish. Qingbo ( Spinibarbus sinensis ), a common cyprinid in southern China, was first pre-acclimated at either high (25 °C) or low (15 °C) temperature for eight weeks and assumed to be at thermal equilibrium. Then, the temperature was reversed, that is, the temperature was decreased from 25 °C to 15 °C in one group, defined as the cooling group, whereas the temperature of the other group was increased from 15 °C to 25 °C, defined as the warming group. The thermal tolerance, swimming performance and feeding metabolism were measured before temperature reversal as well as 1, 2, 4 and 8 weeks. The growth performance was also measured after the temperature reversal. Typical thermal compensation was suggested by a stronger heat tolerance, faster swimming speed and higher postprandial metabolic response in those acclimated at 25 °C than in those acclimated at 15 °C before temperature reversal. Cold tolerance suggested by the critical minimal temperature (CTmin) of the cooling group reached a thermal steady state within one week, whereas the adjustment of heat tolerance to the temperature increase indicated by the critical maximum temperature (CTmax) was much slower, reaching a steady state two weeks after the temperature reversal. The high flexibility of the standard metabolic rate as well as the postprandial metabolism and relatively lower feeding metabolism demonstrated that there were negligible effects at the aerobic scope for other physiological functions during digestion in qingbo, even during the temperature acclimation period. However, there was a slower adjustment of the swimming performance with the temperature decrease, which parallels the change of metabolic capacity. Furthermore, both the cooling and warming treatments had negative effects on growth performance, with the former mainly occurring through extra energy expenditure, whereas the latter mainly occurred through decreased feeding. It suggested that the slow adjustment of heat tolerance after the temperature increase compared to that of cold tolerance might be a challenge for cyprinids distributed in southern China. Furthermore, the decreased metabolic scope and hence swimming performance after the temperature decrease might have a fitness cost in qingbo and possibly other cyprinids in China. [ABSTRACT FROM AUTHOR]

The Baixo Sabor hydroelectric scheme was recently constructed (began operating in 2015), blocking fish migration immediately at the river mouth. As a compensation measure for spawning habitat loss the Vilariça River which confluences with Sabor River, immediately downstream from the Baixo Sabor scheme, was chosen for rehabilitation site as an attempt to replace the spawning grounds lost in Sabor River for the potamodromous cyprinid Iberian barbel ( Luciobarbus bocagei ). Restoration activities included: placement of submerged weirs with fish ramps to increase the lotic/lentic sequence, bank reinforcement, boulder placement and river water profile increase. Water from the nearest reservoir was channeled underground to the lower Vilariça River in order to increase the water flow. The most appropriate volume of water was determined by means of a 1D model coupled with the CASiMiR to determine the weighted usable area for barbel spawners. Nine spawning grounds were identified. Fish migrations began in mid-April when water temperature increased (c. 16 °C) and water flow decreased. Barbel tend to spawn in coarse substrate with shallow water and moderate current. Ontogenetic differences in habitat use were reported, with barbel juveniles preferring weaker currents and deeper zones when compared to spawners. Females also display different preferences, which are more apparent after spawning. Both life-stages exhibit the maximum habitat suitability at c. 1.5 m 3 /s. The habitat model used in this study was able to accurately predict the occurrence of spawning grounds, representing, therefore, a valuable decision-making support tool for river managers. [ABSTRACT FROM AUTHOR]

Highlights • The complete genome of a new strain Cyprinid herpesvirus 2 was sequenced. • The AA sequences of ORF10, ORF107, ORF156 can be used as the mark of SY strain. • Analysis of cis-acting elements and miRNA suggests co-evolution of CyHV-2 and its host. Abstract The haemorrhagic disease of the gill is caused by Cyprinid herpesvirus 2 (CyHV2) infection, which often results in the severe economic losses in the farm of Allogynogenetic crucian carp (ACC). In this study, the genome of CyHV2 strain CyHV2-SY (SY) collected from Sheyang County, Jiangsu Province, China was sequenced. The complete genome of SY is at length of 290,455 bp with 154 potential open reading frames (ORFs) and a terminal direct repeat (TR) of 15,353 bp. Many variations were found by comparison the sequenced CyHV2 genomes. The ORF10, ORF107, ORF156 of SY genome have insertions or deletions of repeat sequences compared with ST-J1 and SY-C1, which may be used as the marks of SY strains. Besides, the promoter sequence analysis showed that 13 of the 150 ORFs have TATA-box elements and 119 of the 150 ORFs have SP1 cis-acting elements in the promoter region (350 bp upstream sequence of the initiation codon ATG). Twenty-eight viral miRNAs candidates were predicted in the CyHV2 genome and expression of 24 virogenes may be regulated by viral miRNAs. Horizontal transfer analysis indicated that 16 and 2 genes in the CyHV2 genome may transfer from the host and bacteria, respectively. By the genome sequencing and sequence mining, our results provided more new clues to further understand CyHV2 genome. [ABSTRACT FROM AUTHOR]

As one of nine piscine viruses recognized by the International Office of Epizootics, spring viraemia of carp virus (SVCV) is an important pathogen bringing high mortality to cyprinids. Up to now, there is no approved therapy on SVCV, making them strong public health threat in aquaculture. In this study, the anti-SVCV activities of 12 plant crude extracts were investigated by using epithelioma papulosum cyprini (EPC) cells. Among these plants, Psoralea corylifolia Linn. showed the highest inhibition on SVCV replication, with an inhibitory percentage of 67.98%. Further studies demonstrated that bavachin (BVN), one of the major constituents of Psoralea corylifolia Linn., was also highly effective to SVCV infection. The half maximal inhibitory concentrations (IC 50 ) of BVN on SVCV glycoprotein and nucleoprotein expression were 0.46 (0.29–0.73) and 0.31 (0.13–0.55) mg/L, respectively. In addition, SVCV-induced apoptosis which may be negative to SVCV replication was inhibited by BVN. The apoptotic cells were decreased 21.42% for BVN compared with SVCV group. These results indicated that the inhibition of BVN on SVCV replication was, in some extent, via blocking SVCV induced apoptosis. Furthermore, cellular morphological damage induced by SVCV was also blocked by BVN treatment. Mechanistically, BVN did not affect SVCV infectivity and cannot be used for prevention of SVCV infection. Time-of-addition and viral binding assays revealed that BVN mainly inhibited the early events of SVCV replication but did not interfere with SVCV adsorption. In conclusion, BVN was considered to develop as a promising agent to treat SVCV infection. [ABSTRACT FROM AUTHOR]

Today, one of the challenges facing modern biology is to develop an accurate, reliable and cost- efficient method for the rapid identification of organisms to species level. Here, we combine high resolution melting (HRM) analysis with DNA barcoding (Bar-HRM) and evaluated its efficiency to discriminate between 215 specimens of 22 common European cyprinid species. After screening the standard barcode region of the mitochondrial cytochrome oxidase gene subunit I (COI) for a distinct fragment, a short region (142 bp) with sufficient sequence diversity was chosen. Using the selected mini-barcode, Bar-HRM analysis was performed to test the potential of this closed- tube method to reveal genetic variation between the cyprinids. To evaluate inter-run reproducibility several Bar-HRM runs were performed on different days using between 8 and 10 specimens per species, resulting in only minor variations in the amplification curves and melting temperatures. The technique was also found to be highly sensitive to single base changes, allowing the detection of geographic variants. 92% of the specimens were unambiguously assigned to the correct cyprinid species whereas in seven individuals the presence of ambiguities prevents the assignment; in case of Barbus barbus the method failed. We provide a guideline for setting up a simple molecular identification tool for unknown samples from a pool of target species with one pair of mini-barcode primers and reduced contamination risk. We demonstrate that Bar-HRM may provide a reliable and simple alternative to Sanger-sequencing based identification in certain applications with the potential to significantly reduce time (up to 241 h) and labor costs (up to 88%) during the process of identification. [ABSTRACT FROM AUTHOR]

The present study redescribes the monotypic genus Afrodiplozoon Khotenovski, 1981, a diplozooid parasite endemic to Africa, based on material collected during surveys carried out in the Limpopo Province, South Africa, from two cyprinid hosts Labeobarbus marequensis and Enteromius paludinosus . Morphometrical analysis of the composition of internal organs and attachment clamps, using light microscopy and scanning electron microscopy, provided details for the genus and species redescriptions. Posterior attachment apparatus can bear up the 15 pairs of the clamps with the first pair of clamps distinctly smaller and not fully developed. Molecular characterization of the second internal transcribed spacer (ITS2) rDNA and phylogenetic analysis revealed the position of Afrodiplozoon polycotyleus as a sister taxon to Paradiplozoon krugerense and Paradiplozoon bingolenisis , distant from other African representatives of the genus Paradiplozoon , Paradiplozoon vaaleense and Paradiplozoon ichtyoxanthon. [ABSTRACT FROM AUTHOR]

An outbreak of a carp disease occurred in a koi pond in early October 2016, Chengdu, southwest of China. Characteristic signs of infected fish include erratic swimming of moribund fish at the water surface, respiratory distress, presence of thick and foggy mucus covering the body and gills. Skin ulcers were also noticed in a few cases. Microbiological, parasitological and virological investigations were carried out with fish samples collected from various localities. Histologically, the gills, kidney and liver showed discernible changes. By analyzing gill tissues in six samples by PCR and nested-PCR for detection of cyprinid herpesvirus 3 (CyHV-3) and carp edema virus (CEV) respectively, PCR products of 292 bp and 478 bp (by using nested primers) could be amplified. The outbreak of carp disease caused by CEV and CyHV-3 mixed infection was confirmed by sequence analysis of the PCR products. The viral load in the gills and kidney were quantified by real-time TaqMan PCR, which in turn would aid the evaluation of the significance of the virus to the etiology of the disease. The result demonstrated that CEV plays the major role to the death of fish. Phylogenetic analyses revealed that the CEV isolate (GenBank accession no. MG189371) showed closest identity to the CEV isolated from UK (KX254027) with 99% homology. To our knowledge, this is the first report a carp disease caused by CEV and CyHV-3 mixed infection in China. [ABSTRACT FROM AUTHOR]

Eighteen orange pigment bacterial strains have been recovered from the gill of naturally diseased golden mahseer ( n = 9), Tor putitora (Hamilton, 1822) in Uttarakhand, India. Isolated strains were characterized by morphological and biochemical characteristics and 16S rRNA gene sequence, and were found to belong to the homogenous group. All the bacterial isolates were Gram-negative, flexirubin positive, catalase and cytochrome-oxidase positive, gliding, short (~ 1.9–2.7 μm in length) and straight rods. The 16S rRNA gene sequence analysis allocated the bacterium to taxa Chryseobacterium scophthalmum (GenBank accession nos. KM822770 , type strain C. scophthalmum TPBLGL 18), with C. scophthalmum strain LMG 13028 T as its closest relative, with 99% sequence similarity. Antibiotic susceptibility tests indicated that all the isolates were susceptible to oxytetracycline (2 μg), erythromycin (10 μg) and sulphadiazine-trimethoprim (100 μg). Histopathological study of the gill of naturally diseased golden mahseer revealed extensive epithelial cell hyperplasia, necrosis, fusion of secondary gill lamellae, degeneration of chloride cells and edema. Inflammation and degenerative changes were also observed in liver, heart, spleen, gall bladder and kidney of naturally diseased fish. The pathogenicity of C. scophthalmum TPBLGL 18 (representative strain) to golden mahseer was confirmed by intraperitoneal (i.p.) injection (0.1 mL volume) with 1.9 × 10 6 CFU/mL of bacterium, which resulted in appearance of gill lesions. Gill lesions in 75% of the challenged fish were reproduced 24 h post-injection (p.i.), and pure colony of C. scophthalmum were re-isolated from the gill, liver and kidney tissue of experimentally challenged golden mahseer. Histopathological studies of gill tissues of i.p injected golden mahseer revealed, clubbing, hyperplasia, hypertrophy, congestion and fusion of secondary gill lamellae. Therefore, in conclusion, our study demonstrates the virulence of C. scophthalmum in golden mahseer as the causative agent of bacterial gill disease (BGD). [ABSTRACT FROM AUTHOR]

Spring viraemia of carp virus (SVCV) causes high morality in several economically important cyprinid fishes, but there is no approved therapy up to now. To address the urgent need for therapeutics to combat SVCV infection, we investigated the anti-SVCV activities of 12 natural compounds and 7 common antiviral agents using epithelioma papulosum cyprini (EPC) cells in this study. From the 19 compounds, we identified arctigenin (ARG) has the highest inhibition on SVCV replication, with maximum inhibitory percentage on SVCV > 90%. And the 48 h half maximal inhibitory concentrations (IC 50 ) of ARG on SVCV glycoprotein and nucleoprotein were 0.29 (0.22–0.39) and 0.35 (0.29–0.41) mg/L respectively. In addition, ARG significantly reduced SVCV-induced apoptosis and recovered SVCV-activated caspase-3/8/9 activity. Further, cellular morphological damage induced by SVCV was blocked by ARG treatment. Mechanistically, ARG did not affect SVCV infectivity. Moreover, ARG could not induce reactive oxygen species (ROS) generation, which plays an antiviral role on SVCV. Interestingly, SVCV-induced autophagy which is necessary for virus replication was inhibited by ARG treatment. These results indicated that the inhibition of ARG on SVCV replication was, at least in part, via blocking SVCV-induced autophagy. Taken together, ARG has the potential to work as an agent for protecting economically important fishes against SVCV. [ABSTRACT FROM AUTHOR]

Understanding freshwater fish population ecology is a pre-requisite for their conservation, management, and exploitation. Many populations of cyprinids, the largest family of freshwater fish, undertake potamodromous migrations. This has important implications for the conservation and management of their stocks. Habitat and connectivity loss are the main factors threatening these stocks. The fine-scale routes (i.e., banks vs. midchannel) of cyprinid spawning migrations in generally turbid rivers are largely unknown, contrary to other taxa such as salmonids, shads, and eels. In this work, we studied the fine-scale leaping behavior of two cyprinid taxa ( Luciobarbus sp., barbels) which support commercial and recreational fisheries. We used fish size and leap distance to the margin as indicative of fine-scale spawning migration routes following the river banks vs. midchannel. The results support the idea that these cyprinids migrate close to the banks, and that the larger adults migrate nearer the banks than the smaller ones. This marks a difference between cyprinids and salmonids, showing that knowledge of cyprinid migration routes can help fisheries managers develop improved, more permeable, barriers and less selective fish pass facilities. Particularly, this behavior of cyprinid species can be applied to optimize the design of fish pass facilities: first, by installing fish passes on each bank of wide rivers, where the large lateral distance may make a single facility difficult to find; and second, by using either a single wider entrance or several narrower entrances distributed over a greater distance from the margins so as to cover the more distant stretch used by the younger adults. [ABSTRACT FROM AUTHOR]

This study presents physical habitat simulations for the fish community in a reach of the Dal River, Korea. The study reach is 2.3 km long, located downstream from the Goesan Dam. The reach is gravel-bed, including a bend. A riffle is present at the apex of the bend, and pools are located before and after the riffle. Field monitoring revealed that five fish species are dominant, namely Zacco platypus , Coreoleuciscus splendidus , Zacco temminckii , Pungfungia herzi , and Acheilognathus yamatsute , and account for 78% of the total fish community. These five fishes, which include both lotic and lentic fishes, were selected as target species. The Center for Computational Hydroscience and Engineering 2D (CCHE2D) model, a 2D shallow water equation solver, and the Adaptive Neuro Fuzzy Inference System (ANFIS) method were used for hydraulic and habitat simulations, respectively. The Mahalanobis distance method was used for identifying outliers in the monitoring data. It was shown that the ANFIS method combined with data quality assessment predicts the Composite Suitability Index (CSI) better than the method without it. The CSI distributions in the study reach are presented for various flows. It was found that the distributions of the combined CSI predicted by the ANFIS method are higher than those predicted by the conventional multiplicative aggregation method with Habitat Suitability Curves (HSCs). In addition, it was revealed that the discharge that yields the maximum Weighted Usable Area (WUA) for the whole fish community is more than twice the discharge yielding the maximum WUA for a single target species. This increased discharge leads to a 58% increase in the maximum WUA for the fish community. [ABSTRACT FROM AUTHOR]

Neonicotinoid insecticide residues are found frequently in different water resources, but the knowledge of their ecological consequences is scanty. The present research focused on one-third of the LC 50 concentration of the two neonicotinoids imidacloprid (66.6 mg/L) and clothianidin (30 mg/L) individually and a mixture (range of 33.3 + 15 mg/L) were exposed to Labeo rohita for 42 days. The investigation evaluated the single and combined insecticidal antagonistic effects on fish cholinesterases (AChE and BChE), oxidative stress activities, and DNA damage (8-OHdG) after intoxication. The imidacloprid (IMI), clothianidin (CLO), and combination intoxication significantly reduced AChE and BChE enzyme activities in the brain, muscle, and serum. The highest levels of AChE inhibition were found in the muscle and brain, whereas the highest levels of BChE were seen in the serum and muscle in the mixed group. The enzymatic and non-enzymatic oxidative activities in the brain and liver varied, with significant increases in superoxide dismutase, catalase activities, lipid peroxidation levels, glutathione S -transferase activity, and a decreasing trend in reduced glutathione levels compared to controls. The 8-OHdG activity increased significantly in proportion to exposure time, while the liver showed the highest increase, followed by the brain in the mixture group. Long-period exposure to neonicotinoids can cause severe neurotoxicity by inhibiting cholinesterase, altering antioxidant activities, and inducing DNA damage (increasing 8-OHdG). The results showed that clothianidin is more toxic than imidacloprid as a single active ingredient, whereas the mixture of two insecticides is more toxic than the single active ingredients. [Display omitted] • Combination of neonicotinoids is more effective than a single insecticide. • A mixture of Imidacloprid and Clothianidin causes severe effects in cholinesterases. • Antioxidants are more susceptible (2 to 4-fold) to neonicotinoids mixtures. • Elevation of 8-OHdG (4 to 4.4-fold) is indicating serious DNA damage. • Neonicotinoids toxicity seriously disturbs the ecological equilibrium. [ABSTRACT FROM AUTHOR]

Knowledge of gamete quality is a prerequisite for developing techniques to fertilize eggs and rear offspring for hatchery production. Our objective was to develop assisted reproductive techniques, via hormonal induction of final oocyte maturation (FOM), for Longspine scraper, Capoeta trutta . Fish were administered injections of salmon gonadotropin-releasing hormone analogue containing anti-dopaminergic drug (Ovaprim™) or saline (control). Effects of Ovaprim on induction of ovulation, gamete quality, embryonic development, and larval survival were later examined with serum steroid hormone levels and ovarian histology. The saline group failed to spawn, whereas Ovaprim accelerated FOM and induced spawning. Fish treated with Ovaprim showed an increase in gonadosomatic index, egg diameter, and wet weight relative to controls. Average absolute fecundity, relative fecundity, fertilization, and hatching rates were 8823 eggs/spawn, 53 eggs/g body weight, 95%, and 91%, respectively. Serum 17α,20β-dihydroxy-4-pregnen-3-one (DHP) levels were significantly enhanced by ∼4-fold in Ovaprim-treated fish compared to the saline-injected fish, while 17β-estradiol levels declined upon FOM in hormone treated fish. Embryonic development closely resembled the teleost scheme, despite variations in timing. Larval survival at 6 and 12 days post-hatch were 98% and 95%, respectively. Results suggest that Ovaprim is efficient for inducing spawning in C. trutta for stock enhancement or hatchery purposes. [ABSTRACT FROM AUTHOR]

A number of studies have revealed ammonia to be toxic to aquatic organisms; however, little is known about its effects under natural conditions. To elucidate the role of ammonia, we conducted 96-h acute toxicity tests as well as a whole-ecosystem chronic toxicity test for one year in ten 600-m 2 ponds. Three common cyprinids, silver carp Hypophthalmichthys molitrix Val. ( H.m. ), bighead carp Aristichthys nobilis Richardson ( A.n. ), and gibel carp Carassius auratus gibelio Bloch ( C.g. ), were used as test organisms. The 96-h LC 50 values of un-ionized ammonia (NH 3 ) for H.m. , A.n. , and C.g. were 0.35, 0.33, and 0.73 mg L − 1 , respectively. In the ponds, annual mean NH 3 ranged between 0.01 and 0.54 mg L − 1 , with 4 ponds having a NH 3 higher than the LC 50 of A.n. (lowest LC 50 in this study). No fish were found dead in the high-nitrogen ponds, but marked histological changes were found in livers and gills. Despite these changes, the specific growth rate of H.m. and A.n. increased significantly with NH 3 . Our pond results suggest that fish might be more tolerant to high ammonia concentrations in natural aquatic ecosystems than under laboratory conditions. Our finding from field experiments thus suggests that the existing regulatory limits for reactive nitrogen (NH 3 ) established from lab toxicity tests might be somewhat too high at the ecosystem conditions. Field-scale chronic toxicity tests covering full life histories of fish and other aquatic organisms are therefore encouraged in order to optimize determination of the effects of ammonia in natural environments. [ABSTRACT FROM AUTHOR]

Riverine fisheries frequently face complex challenges along with the limitations of costly and yet poor data. This is the case of the middle to low reaches of many basins with turbid waters, where large stocks of cyprinids perform wide spawning migrations. These reaches support both commercial and recreational fisheries frequently exploiting stocks of unknown size. There, habitat complexity, turbid waters, and large moving populations hinder the use of non-extractive image techniques (video and photography) for species identification and stock assessment. So far, such techniques are therefore restricted to clear freshwaters and marine environments. In this study, image techniques and sampling methods are used to monitor large riverine stocks of two barbel species ( Luciobarbus sp.) over ten years, while maintaining low economic costs and human effort. The techniques take advantage of the behaviors of the fish relative to a weir and a fish pass while migrating upstream to their spawning grounds. For that, meristic and morphological traits taken from individuals simultaneously captured and photographed were used to identify the taxa and validate this method. The subset of traits still reliable in the images was used to identify free-ranging leaping individuals from a ten-year span photographic database (2007–2016) and determine the annual relative abundance of every taxon. Video images taken at the fishway in dry and humid years were used to estimate absolute stock size in contrasting hydrologic years (2014–2016). Finally, estimates of migrating barbel stocks and their size across hydrologic year variation were obtained through sampling methods and combination of the aforementioned data. The pros and cons of the sampling methods and image techniques used are discussed relative to their applicability to the monitoring and management of cyprinid riverine fisheries in turbid reaches. [ABSTRACT FROM AUTHOR]

Invasive fish species disrupt ecosystems and cause economic damage. Several methods have been discussed to control populations of invasive fish including the release of YY-males. YY-males are fish that have 2 male chromosomes compared to a XY-male. When YY-males mate, they only produce male (XY) offspring. This decreases the female proportion of the population and can, in theory, eradicate local populations by biasing the sex-ratio. YY-males have been used as a population control tool for brook trout in montane streams and lakes in Idaho, USA. The YY-male control method has been discussed for grass carp in Lake Erie, North America. We developed and presented an integral projection model for grass carp to model the use of YY-males as a control method for populations in this lake. Using only the YY-male control method, we found that high levels of YY-males would need to be release annually to control the species. Specifically, these levels were the same order of magnitude as the baseline adult population (e.g., 1000 YY-males needed to be released annual for 20 years to control a baseline adult population of 2500 grass carp). These levels may not be reasonable or obtainable for fisheries managers given the impacts of YY-males on aquatic vegetation and other constraints of natural resource management. [ABSTRACT FROM AUTHOR]

Accelerated by the introduction of Next-Generation Sequencing (NGS), a number of genomes of cyprinid fish species have been drafted, leading to a highly valuable collective resource of comparative genome information on cyprinids ( Cyprinidae ). In addition, NGS-based transcriptome analyses of different developmental stages, organs, or cell types, increasingly contribute to the understanding of complex physiological processes, including immune responses. Cyprinids are a highly interesting family because they comprise one of the most-diversified families of teleosts and because of their variation in ploidy level, with diploid, triploid, tetraploid, hexaploid and sometimes even octoploid species. The wealth of data obtained from NGS technologies provides both challenges and opportunities for immunological research, which will be discussed here. Correct interpretation of ploidy effects on immune responses requires knowledge of the degree of functional divergence between duplicated genes, which can differ even between closely-related cyprinid fish species. We summarize NGS-based progress in analysing immune responses and discuss the importance of respecting the presence of (multiple) duplicated gene sequences when performing transcriptome analyses for detailed understanding of complex physiological processes. Progressively, advances in NGS technology are providing workable methods to further elucidate the implications of gene duplication events and functional divergence of duplicates genes and proteins involved in immune responses in cyprinids. We conclude with discussing how future applications of NGS technologies and analysis methods could enhance immunological research and understanding. [ABSTRACT FROM AUTHOR]

The economic and biological significance of blunt snout bream ( Megalobrama amblycephala ) makes this species important to explore the underlying molecular mechanism of hypoxia response. In the present study, we compared the transcriptional responses to serious hypoxia in skeletal muscle among hypoxia tolerant (MT), sensitive (MS) and control (without hypoxia treatment, MC) M. amblycephala obtained according to the time difference of losing balance after hypoxia treatment. A total of 88,200,889 clean reads were generated and assembled into 44,493 unigenes. Transcriptomic comparison revealed 463 genes differentially expressed among different groups. A similar hypoxia-induced transcription patterns suggested a common hypoxia response involved in cell cycle, p53 signaling pathway, apoptosis, heart contraction and blood circulation. Interesting, four genes, heat shock protein beta-8 ( hspb8 ), cysteine/serine-rich nuclear protein 1 ( csrnp1 ), salt-inducible kinase 1 ( sik1 ), and visinin-like 1a ( vsnl1a ) were up-regulated in MT Vs MC but down-regulated in MS Vs MC. Additionally, FoxO signaling pathway was significantly enriched only in MT Vs MC. These results not only provided the first insights into the mechanism that muscle tissue coped with the hypoxia stress in cyprinid species, but offered a theory base for breeding of M. amblycephala with hypoxia-resistant traits. [ABSTRACT FROM AUTHOR]

The stress response of omnivorous gibel carp ( Carassius auratus gibelio ) and carnivorous largemouth bass ( Micropterus salmoides ) with different nutritional history were evaluated. A 2 × 2 layout, including two fish species (gibel carp or largemouth bass) and two nutritional history (fasted or fed to satiation for four weeks), was used. After feeding or fasting, the fishes were subjected to an acute handling. Fasting resulted in decrease of plasma glucose level and liver glycogen content of gibel carp and largemouth bass. After handling stress, plasma levels of cortisol, glucose and lactate of gibel carp and largemouth bass increased, regardless the fasted fish or fed fish. During the period from 0 h to 24 h post-stress, the fasted gibel carp exhibited lower plasma cortisol and glucose levels, brain and liver glycogen contents, and liver phosphoenolpyruvate carboxykinase (PEPCK) activity compared with the fed counterpart. The plasma glucose level, brain glucose level, brain and liver glycogen contents were lower, while the liver PEPCK and hexokinase (HK) activities were higher, in the faster largemouth bass than the fed counterpart. This study indicates that nutritional history can influence stress response of gibel carp and largemouth bass, and the stress response is less severe in the fasted fish relative to the fed counterpart. This study also reveals that gibel carp and largemouth bass may have different strategies in response to fasting and acute handling stress. [ABSTRACT FROM AUTHOR]