Carassius Auratus Gibelio Research Articles

Assessment of Water Quality and Parasitofauna, and a Biometric Analysis of the Prussian Carp of the Romanian Lentic Ecosystem in Moara Domnească, Ilfov County

The aim of this study was to perform a morphometric analysis of Prussian carp individuals collected from the Moara Domnească pond in Ilfov County, Romania. This was accompanied by a physico-chemical characterization of the water, which was sampled from the same location. Consequently, we analyzed a total of 60 Prussian carp individuals that were caught in April (N = 32) and May 2023 (N = 28). For the Carassius gibelio in the study site, we provided, for the first time, data on the weight–length relationships (WLRs), the Fulton K condition factor and the biometric features, including the total length (TL), standard length (SL), head length (HL), snout length (SNL), body depth (BD), girth and ratios for the TL/HL, as well for the TL/BD and TL/SL. A negative growth type was estimated for both the samples of C. gibelio. Based on other studies and fishing reports, besides C. gibelio, there are another 11 species that belong to the Cypriniformes order, and there are two teleost members of the Perciformes order (Lepomis gibbosus and Perca fluviatilis)—these were also associated with this habitat. Water samples were collected from 12 sampling points (SP), which were subjected to physico-chemical characterizations that consisted of an assessment of the turbidity (T), pH, electrical conductivity (EC), chloride (Cl−), total hardness (TH), oxygen regime parameters, phosphate phosphorus (P-PO43−), nitrate nitrogen (N-NO3−), nitrite nitrogen (N-NO2−) and ammonium nitrogen (N-NH4+) levels. In addition, considering their characteristics (high toxicity, non-biodegradability, long-range atmospheric transport and bioaccumulation potential), a number of organochlorine pollutants (OCPs) were identified. The total hardness values presented a very significant correlation with conductivity (r = 0.5974 ***) and with pH (r = 0.5854 ***). The results allowed for the water samples to be placed into the quality classes established by legislation, and they were also discussed in relation to the fishes’ requirements.

DETERMINATION AND EVOLUTION IN TIME OF RADIOACTIVITY LEVELS IN FRESHWATER FISH (CARASSIUSGIBELIO) SAMPLED FROM OLT RIVER, ROMANIA

The paper presents a monitoring activity of the Freshwater fish (Carassius gibelio) samples consumed in Olt River, Romania. A monitoring study lasting 9 years (2014-2022) was realized. Two sampling points for the Olt River were chosen, the first one upstream of the discharge point of the magistrate channel “Deversor Olt” (background location) and respectively the second sampling point downstream of the liquid effluents discharge point (indicator location). A maximum activity concentration for40K of 95.75 Bq∙kg-1 fw, is observed. The activity of interest radionuclides (7Be, 51Cr, 60Co, 137Cs, 226Ra, 235U) is below the detection limit. The method used was high resolution gamma ray spectrometry performed with an HPGe detector. It was observed that the values recorded for the background location had a slight difference compared with the values recorded in the indicator locations. The nuclear activity in the pre-operational stage of the Experimental Pilot Plant for Tritium and Deuterium Separation did not have any impact on the environment so far. This study creates a unique database that could be relevant for further Operational Program for Environmental Monitoring of the Experimental Pilot Plant and other economical agents in the area.

Myxobolus nekrasovae n. sp. (Cnidaria, Myxozoa) is a new species parasitizing the gills of the gibel carp, Carassius auratus gibelio

A new Myxobolus species, Myxobolus nekrasovi n. sp., was found in the gill arch of the gibel carp Carassius auratus gibelio during investigation of fish myxosporean fauna of ponds of Lake Baikal basin. The parasites were studied on the basis of spore morphology, as well as with histological and molecular methods. Mature spores of M. nekrasovi n. sp. are ellipsoidal in frontal view and lemon-shaped in lateral view, measuring 13.84 ± 0.4 (12.2–15) μm in length, 9.73 ± 0.2 (8.5–10.7) μm in width, 6,75 ± 0.1 (6.0–7.6) μm in thickness. Polar capsules are unequal and pyriform, measuring: length 6.31 ± 0.1 (5.4–7.4), width 3.49 ± 0.04 (3.12–4) μm and length 2.88 ± 0.1 (2.1–3.5), width 1.4 ± 0.03 (1–1.6) μm. Phylogenetic analysis with the SSU rDNA gene shows Myxobolus nekrasovae n. sp. as a sister species of the subclade formed by Thellohanellus sinensis, Myxobolus acutus, M. zhaltsanovae that infect gibel carp Carassius auratus gibelio.

Alterations of Plasma Biochemical and Immunological Parameters and Spatiotemporal Expression of TLR2 and TLR9 in Gibel Carp (Carassius auratus gibelio) after CyHV-2 Infection.

Cyprinid herpesvirus II (CyHV-2), a highly contagious pathogen of gibel carp (Carassius auratus gibelio), causes herpesviral hematopoietic necrosis disease (HVHND) and enormous financial losses. However, there is limited information available regarding the changes in plasma biochemical and immunological parameters and the response characteristics of Toll-like receptor 2 (TLR2) and Toll-like receptor 9 (TLR9) in gibel carp after CyHV-2 infection. To address this knowledge gap, a sub-lethal CyHV-2 infection was conducted in gibel carp, and the sample was collected daily from 1 to 7 days post infection. The plasma biochemical analyses showed significant decreases in the content of glucose, total cholesterol (TCHO), and total protein (TP), along with marked increases in the level of uric acid, urea, creatinine (CREA), Complement 3 (C3), immunoglobulin D (IgD), and immunoglobulin M (IgM) as well as in the activity of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) in the infected group. Compared with the control group, the concentration of cortisol, triglyceride (TG), and Complement 4 (C4) had no noticeable alterations in the infected group. Real-time quantitative PCR analysis showed significant upregulation of TLR2 and TLR9 mRNA expression in the spleen, kidney, brain, liver, intestine, and gill post CyHV-2 infection. Interestingly, a time- and tissue-dependent expression profile has been comparatively observed for TLR2 and TLR9 in the above tissues of gibel carp after CyHV-2 infection, suggesting distinct roles between TLR2 and TLR9 in antiviral response to CyHV-2 infection. Overall, our results demonstrated that CyHV-2 infection led to the disruption of the physiological metabolic process and damage to the liver and kidney, and induced different spatiotemporal expression patterns of TLR2 and TLR9, ultimately stimulating antiviral response via innate and adaptive immune system. These findings may provide a deeper understanding of the host immunity response to CyHV-2 infection and offer novel perspectives for the prevention and treatment and therapeutic drug development against CyHV-2.

Health risk assessments of heavy metal concentrations via consumption of an invasive species, Carassius gibelio, from two large freshwater lakes of Türkiye

Health risk assessments of heavy metal concentrations via consumption of an invasive species, Carassius gibelio, from two large freshwater lakes of Türkiye

Sampling bias of invasive gibel carp and threatened crucian carp: Implications for conservation

Invasive alien species cause significant loss of biodiversity. The presence of invasive alien species is often left unnoticed until they become highly abundant, and early detection by citizens can serve as an early indicator of invasion. Here, we aimed to investigate the detection probability of invasive gibel carp (Carassius gibelio) and native critically endangered species, crucian carp (Carassius carassius), using typical methods employed by conservation agencies (fyke nets) and citizens (angling). Three sites with native crucian carp, nine sites with species syntopy and five sites with invasive gibel carp were investigated. The proportion of species caught by each method was compared using catch per unit effort (CPUE) as a measure of fish density and calculated as the number of fish of each species caught per hour. Species detectability by trapping and angling and the effects of waterbody type on the species catch success were analysed using a Beta regression model. Although the species are closely related and occupy similar positions in the ecosystem, the results showed a high affinity of invasive gibel carp for detection by angling (citizen method), while native crucian carp showed higher catch success in trapping (common professional monitoring method), to an extent that one species can be easily missed when sampled by only one of the methods. These results bring two important findings, namely the need to include citizen knowledge as an indicator of the progress of invasive gibel carp, and the potential danger of underestimating the invasion by conservationists and scientists. The results also suggest that the presence of native crucian carp in syntopy with invasive gibel carp may be overlooked by citizens. This study provides an example of detection bias that can hinder conservation efforts if neglected.

Long-term sublethal exposure to polyethylene and tire wear particles: Effects on risk-taking behaviour in invasive and native fish

Anthropogenic polymeric particles pollute even the most remote ecosystems and may compromise organisms' behaviour and movement skills. It is expected that invasive species cope better with pollutants than native species (i.e., pollution resistance hypothesis). In this study, invasive gibel carp (Carassius gibelio) and native crucian carp (Carassius carassius) were used as model organisms. Specimens were fed daily with food pellets (1 % body weight) added with 0.1 % polyethylene (PE), tire wear particles (TWPs) and control. Their behavioural parameters were compared before and after 14 and 60 days of exposure. Additionally, we evaluated burst swimming capacity after 60 days of exposure to the treatments. The fishes exposed to the PE and TWPs treatments showed significant trends toward increased boldness scores and, in the PE treatment, higher utilization of the open field, and both behavioural changes are associated with higher risk-taking. Invasive gibel carp had substantially better swimming performance than crucian carp, but the expected trend in relation to the treatments was not found. Fish exposed to sublethal doses of PE and TWPs showed signs of behavioural changes after two months of exposure that may affect risk-taking behaviour, which might impact species interactions with predators.

Fish in Burial Practice of the Sargat Culture Population of the Early Iron Age of the Baraba Forest-Steppe (According to the Materials of the Mound No. 51 of the Ust-Tartas Burial Ground)

Purpose. The Sargat culture fish remains are still given very little attention. The purpose of this work is to present materials that testify to the use of fish in the burial practice of the Sargat population of Baraba.Finds (artefacts). In the field season of 2022, the Toguchin team of the IAET SB RAS explored the mound no. 51 of the Ust-Tartas burial ground of the Sargat culture. Among the various artifacts found on the mound territory there were objects containing animal bones, and objects containing fish remains, as well as objects containing both animal bones and fish remains.Methods. Preparation of the osteological collection of fish remains was carried out in 2022–2023 using a cameral processing method. The collection contains mainly scales, bones of the visceral part of the skeleton of the head, bones of the skull. Fragments of the axial skeleton (vertebrae, Weberian apparatus, urostyle) and pharyngeal teeth appear in a smaller number. In the pocess of the collection formation, it was found that the best preservation of samples is ensured by materials that have not been preliminary washed and cleaned: the bone structures are less brittle. Therefore, fragments of the fish skeleton were separated from the soil in the laboratory.Results. For the most part, accumulations of fish remains are represented by large specimens of older age groups (from 7+ years, mostly 10+ and more). The identified species composition of fish in samples of the Early Iron Age includes representatives of the family Cyprinidae (ide Leuciscus idus, goldfish Carassius gibelio) and family Percidae (perch Perca fluviatilis). In addition to the listed species, remains of the family Acipenseridae (sterlet Acipenser ruthenus) and the family Cyprinidae (golden crucian carp C. Carassius) were noted in the earlier objects. Object 10 stands out: it is a butt containing not only tools and animal bones, but also fish remains. For the first time, the fact of fish use in the funeral rite of the Sargatians was revealed. The fish remains in the mound testify that the population of the Sargat culture who created this site practiced fishing along with their main occupation – cattle breeding.Conclusion. Materials of the mound no. 51 of the Ust-Tartas burial ground, containing fish remains, are an example of the local population adaptation to the natural environment. The Tai tract was a natural oasis, which not only provided a forage base for livestock but also ensured an easy catch of fish. Human adaptation to the natural conditions in the Baraba region was quite successful, as evidenced by the fact that fish was a part of the funeral rite along with products of animal origin. It was often included in butts in some objects, which correlates with sacred actions.

Fish diversity assessed by eDNA detection methods in the Rioni River

Due to anthropogenic influences, habitat degradation and a continuous loss of biodiversity in freshwater ecosystems are occurring on a large scale, while these ecosystems constitute invaluable natural resources. Therefore, it is essential to study and monitor freshwater ecosystems to guide conservation efforts. Freshwater ecosystems are one of the less-studied fields in Georgia. Studies about the species distribution of many taxa and/or regions carried out during the last century have not been updated for decades. Here, we report the results of an environmental DNA (eDNA) metabarcoding exercise, based on samples collected from the Rioni River, a tributary to the Black Sea and a crucial aquatic ecosystem regionally and globally. The only comprehensive review of the fish of the Rioni River dates back to 1956. We compared the eDNA-based taxonomic composition to the known faunal composition within the Rioni River and found that the eDNA-based taxonomic coverage approached 75% of the expected total fish fauna. A number of new species occurrences were also found, including the first detection of three invasive alien species (Carassius gibelio, Pseudorasbora parva, Rhinogobius lindbergi) in the Rionis River Basin and a new country record of the ninespine stickleback (genus Pungitius) for Georgia. In spite of the usefulness of the eDNA metabarcoding approach, the sparsity of the fish DNA barcode reference library for the region emerged as a limitation to this study. However, our findings still represent a great leap forward in updating fish status on the Rioni River and testing the effectiveness of the eDNA sampling for aquatic species.

Evolution of Skipper (SK), a family of DD34E/Tc1 transposons, in animals

Abstract High diversity and differential evolution profiles have been observed for DD34E/Tc1 transposons; several families originating from these groups, such as DD34E/ZB, DD34E/SB, DD35E/TR, DD36E/IC, and DD38E/IT, have been well defined. Even though Frisky, Tiang, Tsessebe, and Topi transposons have been identified in Anopheles gambiae, their taxonomic distribution and phylogenetic relationship in nature remain largely unknown. The evolutionary profiles of Frisky, Tiang, Tsessebe, and Topi homology transposons were investigated in the current study. In total, 254 homology transposons of Frisky, Tiang, Hob, Tsessebe, and Topi were obtained in 200 species by data mining. The phylogenetic tree revealed that these transposons were classified into five main clades (Frisky, Tiang, Hob, Tsessebe, and Topi) forming a monophyletic clade with 98% bootstrap support, belonging to the DD34E/Tc1 group, and named as Skipper (SK). SK transposons show a wide distribution in animals; however, differential taxonomic distribution patterns were observed for the subfamilies of Frisky, Tiang, Hob, Tsessebe, and Topi; extensive invasion of Frisky in animals was found, whereas Tiang, Hob, Tsessebe, and Topi were mainly detected in Diptera. SK elements share a similar structural organization and display high sequence identities across subfamilies. Evolutionary dynamics and structural analysis revealed that SKs in some species, such as Bombyx mori, Lordiphosa magnipectinata, Carassius gibelio, Triplophysa dalaica, and Silurus glanis, have recently evolved and present as intact copies, indicating that SKs in these genomes may be active. Together, these observations improve our understanding of the diversity of DD34E/Tc1 transposons and their impacts on genome evolution in animals.

α-lipoic acid ameliorates hepatotoxicity induced by chronic ammonia toxicity in crucian carp (Carassius auratus gibelio) by alleviating oxidative stress, inflammation and inhibiting ERS pathway

High environment ammonia (HEA) poses a deadly threat to aquatic animals and indirectly impacts human healthy life, while nutritional regulation can alleviate chronic ammonia toxicity. α-lipoic acid exhibits antioxidative effects in both aqueous and lipid environments, mitigating cellular and tissue damage caused by oxidative stress by aiding in the neutralization of free radicals (reactive oxygen species). Hence, investigating its potential as an effective antioxidant and its protective mechanisms against chronic ammonia stress in crucian carp is highly valuable. Experimental fish (initial weight 20.47 ± 1.68 g) were fed diets supplemented with or without 0.1% α-lipoic acid followed by a chronic ammonia exposure (10 mg/L) for 42 days. The results revealed that chronic ammonia stress affected growth (weight gain rate, specific growth rate, and feed conversion rate), leading to oxidative stress (decreased the activities of antioxidant enzymes catalase, superoxide dismutase, glutathione peroxidase; decreased total antioxidant capacity), increased lipid peroxidation (accumulation of malondialdehyde), immune suppression (decreased contents of nonspecific immune enzymes AKP and ACP, 50% hemolytic complement, and decrease of immunoglobulin M), impaired ammonia metabolism (reduced contents of Glu, GS, GSH, and Gln), imbalance of expression of induced antioxidant-related genes (downregulation of Cu/Zu SOD, CAT, Nrf2, and HO-1; upregulation of GST and Keap1), induction of pro-apoptotic molecules (transcription of BAX, Caspase3, and Caspase9), downregulation of anti-apoptotic gene Bcl-2 expression, and induction of endoplasmic reticulum stress (upregulation of IRE1, PERK, and ATF6 expression). The results suggested that the supplementation of α-lipoic acid could effectively induce humoral immunity, alleviate oxidative stress injury and endoplasmic reticulum stress, and ultimately alleviate liver injury induced by ammonia poisoning (50–60% reduction). This provides theoretical basis for revealing the toxicity of long-term ammonia stress and provides new insights into the anti-ammonia toxicity mechanism of α-lipoic acid.

Mass mortality events associated with cyprinid herpesvirus 2 (CyHV-2) infection in wild Prussian carp Carassius gibelio in the Netherlands, and molecular biology of virus strains.

In 2011 and 2015, four mass mortalities of Prussian carp (Carassius gibelio) were observed in a recreational freshwater lake and open freshwater in the western part of the Netherlands. Cyprinid herpesvirus 2 (CyHV-2) infection was suspected in these cases, based on presumptive gross diagnosis. To elucidate the cause of the mass mortalities diagnostic PCR assays were performed for CyHV-2, based on the helicase gene. Furthermore, the viral isolates were genotyped by sequencing the enlarged marker A and marker B sequences. Diagnostic PCR revealed that three of four samples were positive for CyHV-2, indicating these three mass mortalities were associated with CyHV-2 infection. The marker A sequence from one of the isolates found in this study was identical to those from different locations such as Asia and Middle East, suggesting a link among the isolates. This is the first detailed report on mass mortalities of Prussian carp associated with CyHV-2 infection in natural aquatic environments in the Netherlands. Since 2015, additionally, in total three CyHV-2 associated outbreaks of Dutch Prussian carp were seen in 2016 and 2020. These outbreaks in Prussian carp from lakes and open water suggest that the virus has been spreading in natural freshwaters in the Netherlands.

Гістологічна структура зябер карася сріблястого річки Самара Дніпропетровської області

Purpose. To study the histological structure of the gill apparatus of the Prussian carp (Сarassius gibelio) from the point of view of the presence of pathologies with differentiation according to areas with different levels of anthropogenic pressure of the Samara River in the Dnipropetrovsk region. Methodology. The generalized sutdy results were obtained during 2019–2021. The study was conducted within three sampling sites with different types of human impact. The object of the study were age-6 Prussian carps of both sexes. Histological studies were performed in accordance with generally accepted methods. Gills were obtained by anatomical dissection from freshly caught fish. Photographs of histological specimens were taken using a digital camera “SciencelabT5005.17M” and an microscope “Ulab XY-B2TLED”. Measurements of the samples were performed using the “ScienceLabView7”. Statistical processing of the obtained data was carried out in MS Excel 2010. Findings. The conducted histological studies showed that pathological changes in the structure of the gill apparatus were observed in age-6 Prussian carps in all sampling sites of the Samara River. In particular, such pathologies as curvature of lamellae terminals, accumulation of mucus and hyperplasia of the epithelium of gill filaments, fusion of lamellae were found. Single cases of necrosis and twisting of lamellae threads were recorded. Most often, histopathological changes in the gill apparatus were observed in fish caught near the city Novomoskovsk. Organometric studies showed that there was no significant difference between the length and width of gill arches of Prussian carp from different sampling sites. The length and width of the lamellae of the gill apparatus was the largest in individuals sampled near the city Novomoskovsk, which may indicate a greater need for oxygen for the fish body in the specified area. The length of the respiratory lamellae was the lowest in Prissian carp sampled near the village of Novoselivka. The lowest width of the lamellae were found in fish from the village of Khashcheve. The obtained data give reason to conclude that the conditions of existence for Prussian carp are most favorable near the village of Novoselivka. Originality. For the first time the histological structure and pathology of the gills aparatus of Prussian carp in the conditions of the Samara River in the Dnipropetrovsk region was studied. Practical value. The obtained data on the histological changes of the gill apparatus of fish can be used to identify adaptive reactions, will allow assessing the impact of anthropogenic factors on hydrobionts, and will also provide the opportunity to monitor the morpho-physiological state of a specific population under the impact of pollutants of various origins. Key words: Prussian carp, gill apparatus, morphological and histological indicators.

Оценка экологического состояния реки Урал методом флуктуирующей асимметрии

The article presents the results of the assessment of the ecological state of the Ural River by the method of fluctuating asymmetry using pond frog (Rana lessonae) and silver carp (Carassius gibelio) as bioindicators. The studies were carried out on 4 sections of the river that differ in anthropogenic load. The fluctuating asymmetry method is based on the analysis of the symmetry violation of the development of morphogenetic homeostasis indicators Rana lessonae and Carassius gibelio under the influence of anthropogenic factors. The study made it possible to assess the state of the Ural River in the studied areas of the reservoir by the stability of the development of the bioindicators Rana lessonae and Carassius gibelio. Keywords: BIOINDICATION, FLUCTUATING ASYMMETRY, RANA LESSONAE, CARASSIUS GIBELIO, URAL RIVER

Microplastic ingestion by invasive Prussian carp (Carassius gibelio) used in fishmeal production in Türkiye.

MP contamination in the gastrointestinal tract (GIT) of Prussian carp (Carassius gibelio) used in fishmeal production was examined. The samples were collected from Balık Lake, Karaboğaz Lake, and Liman Lake located in Kızılırmak Delta, Türkiye. The overall average abundance was 3.20±0.18 MP per fish and 0.036±0.002 MP per g. No significant correlation was determined between the MP abundance in the fish, fish length, and fish weight. The polymers were composed of 56.91% PET, 25.20% PP, 9.76% PE, and 8.13% PA. The determined shapes were fiber (78.0%), fragment (13.46%), and film (8.54%). The size ranged between 112 and 4775 μm with an average of 1341.41±66.07 μm. Depending on the occurrence frequency and abundance, it can be concluded that Carassius gibelio can be considered a MP vector in fishmeal. The results provide an essential baseline for future MP studies on the potential effects of MPs on aquatic organisms, fate, and impact on the fishmeal production process, aquaculture practices, and human health.

Efficient showering vaccination with a live attenuated vaccine against herpesviral hematopoietic necrosis in goldfish

Herpesviral hematopoietic necrosis caused by cyprinid herpesvirus 2 (CyHV-2) frequently affects farmed goldfish Carassius auratus and gibel carp C. auratus gibelio, leading to significant economic damage. In our previous study, a live attenuated vaccine, called the P7-P8 vaccine strain, was developed by propagating virulent CyHV-2 in two non-natural host cell lines. The vaccine demonstrated high protective efficacy in goldfish with no signs of virulence reversion. Methods that reduce the costs of the procedure, including labor costs, are warranted for the practical application of this vaccine in goldfish aquaculture. The aim of this study was to explore alternative vaccination protocols for the P7-P8 strain in goldfish. First, we tested the previous standard administration protocol which is the bath vaccination with 1: 1000 diluted vaccine cultures for 2 h. In the simple first step to reduce vaccine virus culture, we examined the bathing protocol with more-diluted virus culture (ranging from 1: 1000 to 1: 81,000). The relative percentage survival (RPS) after the virulent virus immersion challenge for 2 h at 21 days post-vaccination was remarkably decreased in a dose-dependent manner; a dilution of 1: 3000 resulted in a 19% reduction from that used in the standard bathing protocol. Therefore, alternative methods (dipping and showering vaccination protocols) were tested using a 1: 100 dilution vaccine culture (10-fold more concentrated than the standard protocol) with short exposure times. Dipping vaccination for 10 s, 1 min, 2 min, and 5 min showed sufficient RPS of 82.4%–100%. The 10 s process was repeated six times using the same vaccine solution, resulting in an RPS >89%. In the showering vaccination protocol, the vaccine solution (1: 100 dilution; 1 mL, 3 mL, or 5 mL) was showered onto 20 goldfish on a net and held for 10 s, resulting in an RPS of >89%. We selected the showering vaccination as the suitable vaccination protocol. The effectiveness of this vaccination protocol was tested using the virus challenge by employing the cohabitation method with infected fish. The results showed high protective efficacy with an RPS of 65%–100%. This study demonstrated that the showering vaccination protocol, which uses small amounts of vaccine culture and produces less waste vaccine solution with short labor time, may be considered as a suitable alternative to the standard bath method in goldfish aquaculture.

Heterosis versus breakdown in cyprinid hybrids associated with SVCV infection revealed by transcriptome profile analysis of head kidney

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

The first detection of Myxobolus lentisuturalis Dyková, Fiala et Nie, 2002, a highly pathogenic muscle-infecting parasite of gibel carp (Carassius auratus gibelio Berg, 1932) in Hungary.

Myxobolus lentisuturalis is a myxosporean parasite infecting the musculature both of goldfish (Carassius auratus auratus) and gibel carp (Carassius auratus gibelio). The species was originally described in China from gibel carp that is a common fish for sport fishing in Hungary meanwhile is one of the most popular farmed fish in China due to its high demand. Eighteen gibel carp with distortions were collected from a barrage pond in southern Hungary. All fish had large humps in the dorsolateral region due to infection of the muscle between the head and the dorsal fin. The swollen degenerated tissue was filled with myxozoan spores, which were collected for morphological and molecular studies. By size and morphology, the spores were consistent with morphological description of M. lentisuturalis. Histopathological examination showed that the formation of plasmodia containing myxospores leads to severe destruction of muscle tissue. The 18S ribosomal DNA and 28S ribosomal DNA data of the samples presented matched with previous sequences of M. lentisuturalis in GenBank. Phylogenetic analyses confirmed that our sequences belong to a monophyletic group with them supported by a high bootstrap. This study highlights the occurrence of a highly pathogenic myxozoan, M. lentisuturalis in Hungary as a new geographical location.

Düden Çayı'ndaki (Antalya, Türkiye) Endemik ve Tanıtılan Cyprinid Balıklarının Vücut Kondisyonu ve Büyüme Tiplerinin Mekansal Değişimi

In this study, we evaluated the parameters of the length-weight relationship and the relative condition factor of endemic Pseudophoxinus antalyae and introduced fish species, Carassius gibelio and Cyprinus carpio in the Kırkgöz Spring-Duden Stream basin. A total of 269 fish were captured from three different sites of the basin from May to September 2022. There were differences in mean length and weight were observed between populations from sites 1 to 3 for three fish species. Negative allometric growth was observed in site 2 population of P. antalyae, whilst site 1 and 3 showed positive allometric growth, and the condition factor (K) for only site 1 was above 1. The populations of C. carpio from sites 2 and 3 showed positive allometric growth, while C. giebelio was negative allometry. K >1 for C. carpio at site 3 and for C. gibelio at site 2. This study can inform both fisheries biology and environmental management for the development and conservation of endemic fish stock.

Intermittent hypoxia differentially affects metabolic and oxidative stress responses in two species of cyprinid fish.

Oxygen fluctuations are common in freshwater habitats and aquaculture and can impact ecologically and economically important species of fish like cyprinids. To gain insight into the physiological responses to oxygen fluctuations in two common cyprinid species, we evaluated the impact of short-term intermittent hypoxia on oxidative stress and metabolic parameters (including levels of prooxidants and oxidative lesions, antioxidants, mitochondrial enzyme activities, mitochondrial swelling, markers of apoptosis, autophagy and cytotoxicity) in silver carp Hypophthalmichthys molitrix and gibel carp Carassius gibelio. During hypoxia, gibel carp showed higher baseline levels of antioxidants and less pronounced changes in oxidative and metabolic biomarkers in the tissues than silver carp. Reoxygenation led to a strong shift in metabolic and redox-related parameters and tissue damage, indicating high cost of post-hypoxic recovery in both species. Species-specific differences were more strongly associated with oxidative stress status, whereas metabolic indices and nitrosative stress parameters were more relevant to the response to hypoxia-reoxygenation. Overall, regulation of energy metabolism appears more critical than the regulation of antioxidants in the response to oxygen deprivation in the studied species. Further research is needed to establish whether prioritizing metabolic over redox regulation during hypoxia-reoxygenation stress is common in freshwater cyprinids.