The effect of Spirulina platensis on water quality factors, biofloc composition, growth efficiency, fatty acid and amino acid profile of fillets, carcass composition, antioxidant activities, bacterial population, and gene expersion in common carp (Cyprinus carpio) reared in a system without water exchange

Transcriptomic profiling reveals tetrabromobisphenol A-induced dysregulation of hepatic lipid homeostasis in common carp (Cyprinus carpio).

Optimizing Aeromonas hydrophila vaccine efficacy in common carp: The role of free vs. microencapsulated Lactiplantibacillus plantarum and Lactobacillus delbrueckii bulgaricus.

Microplastic and nanoparticles contaminated feed impairs common carp (Cyprinus carpio) growth performance and metabolic regulation

Heavy metals and metalloids (HMLs) are toxic, non-biodegradable pollutants that can accumulate in sediments and aquatic organisms, posing significant risks to ecosystems. Their persistence in the environment leads to long-term contamination, harming aquatic life, disrupting ecosystems, and threatening water quality. HMLs have not been extensively studied in Dukan Lake, Kurdistan region, northern Iraq; thus, their environmental fate remains largely unknown. To address this, we conducted a field monitoring study to examine the presence of HMLs in the lake, collecting samples from common carp, sediment, and water. HMLs were regularly measured during the sampling period, with median concentrations detected in common carp (Cyprinus carpio) tissues (0.01–2.9 × 102 µg/g), sediment (0.5–7.8 × 102 µg/g), and water (0.01−6.9 µg/L). Fe, Mg, and Zn were the dominant metals across all samples. Seasonal variations of the HMLs were observed, with higher concentrations found in summer and autumn seasons compared to winter and spring, indicating the impact of temperature and precipitation. Despite high concentrations in sediment and water, HMLs accumulation remained below the threshold. These results underscore the significance of lake monitoring in evaluating ecosystem health and surface water quality. The environmental impact and ecotoxicological significance of HMLs from places that are not monitored and still need further evaluation.

This study was conducted to evaluate the effects of chia seed oil (CSO; Salvia hispanica L.) on the growth performance, haematological-biochemical parameters, immune-related gene expression, and disease resistance to Aeromonas hydrophila in common carp (Cyprinus carpio). The fish were fed diets containing 0%, 0.5%, 1%, and 2% CSO for 60 days. The results showed a significant improvement in final weight, specific growth rate (SGR), and feed conversion ratio (FCR) in fish fed diets containing 1% and 2% CSO compared to the control group. Haematocrit (Hct) and haemoglobin (Hb) levels increased in the CSO groups, while serum triglyceride and cholesterol levels decreased significantly, particularly in the 1% CSO group. The observed decrease in liver enzyme activities (AST, ALT) suggested a hepatoprotective effect of CSO. In the stress test with A. hydrophila, the highest survival rate (80%) was recorded in the 2% CSO group. Furthermore, gene expression analyses performed on spleen tissue revealed an increase in the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-8 in the groups fed with CSO, particularly at the 1% level. These findings indicate that adding 1–2% CSO to carp feed promotes growth, improves lipid metabolism, strengthens immune status, and increases resistance to bacterial infection. Consequently, the use of CSO as a sustainable and functional additive to fish oil in fish feed is suggested.

Non-lethal diet sampling is essential where individual-level monitoring and welfare matter, yet evidence on season-long outcomes in agastric fishes is scarce. We tested syringe-based gut flushing in pond-reared common carp Cyprinus carpio over one growing season (April-September) using PIT-tagged fish assigned a priori to three handling histories: flushed (sedated, measured, flushed), handled-only (sedated, measured), and unhandled controls. At harvest, recapture (survival proxy) remained high and statistically similar among handled groups and growth to harvest did not differ across treatments (end-point mass: flushed 1857.3 ± 367.4 g; handled-only 1769.7 ± 311.8 g; unhandled 1731.9 ± 392.6 g). A mid-season divergence in July (handled-only > flushed in weight gain) was transient and absent at harvest. Operational performance scaled predictably: total water required to clear effluent increased with fish size (~20 mL in small carp to >90 mL in large individuals; occasional ~120 mL) and varied seasonally, rising from May to August and easing in September. Practical safeguards (rounded catheters guided between pharyngeal teeth; conservative advancement ≤2 cm beyond the teeth; controlled bolus infusions; standardised recovery) supported complete evacuations with low injury risk. Collectively, these results validate gut flushing as a field-ready, non-lethal method that can be integrated into routine dietary monitoring of agastric cyprinids without compromising survival or harvest growth, while providing simple, size- and season-based parameters to standardise protocols across studies.

Hydropeaking and invasive non-native fish species are among the most significant pressures to riverine ecosystems and freshwater biodiversity, yet, fish responses to hydropeaking and the effectiveness of mitigation measures remain largely uncharted. This study addressed this gap through an indoor flume experiment assessing how two flow events influenced the use of artificial habitats (flow refuges) by the invasive non-native common carp (Cyprinus carpio). Fish behaviour was evaluated for a base flow (continuous 7 L/s) and a peak flow (increase from 7 L/s to continuous 60 L/s). Refuge use was quantified within three regions of two flow refuges alongside physiological responses (glucose and lactate) to stress and fatigue. Results were compared with previous findings for the native Iberian barbel (Luciobarbus bocagei) tested under the same conditions. No significant differences in lactate or glucose levels were observed between flow events for either species. In contrast, both species showed significantly higher frequency and duration of refuge use during peak flow. The native Iberian barbel displayed more frequent and prolonged refuge use than common carp, suggesting a stronger dependence on these structures for hydrodynamic sheltering. These findings raise concerns that intensified competition for flow refuge use may impede native species’ access to these structures.

This study was conducted to test the effect of adding an insect powder mixture on the performance of common carp fry which had initial body weight attained (16.65±0.01) g. A total of 72 fish they were randomly distributed into 4 treatments with 3 replicates (6 fish per replicate). A commercial Ferdaneh diet with a crude protein content of 30% and a gross energy 412 kcal/g was used. A commercial insect powder mixture (grasshopper and mealworms) was added to the diets at the following experimental levels: T0 was the control treatment without any addition. And it was added to T1, T2, and T3 at levels of 1%, 2%, and 3%, respectively. Fish performance was tested after 60 days of the experiment, based on weight gain, daily growth rate, relative growth rate, specific growth rate, feed conversion ratio, feed conversion efficiency, and protein efficiency ratio. The results of the statistical analysis showed that all addition treatments significantly exceeded on the control treatment, in the following order: T3 then T2, followed by T1, for all studied parameters hence, we conclude that common carp fry showed the best growth performance after adding the insect powder mixture at the above-mentioned levels to their diet, particularly at 3%.

Distribution and risk assessments of 210Po in the body organs of common carp (Cyprinus carpio) and Barbel Chub (Squaliobarbus curriculus) within Red River, Vietnam.

Small RNA transcriptome profiling reveals an essential role for miR-133b-3p_3 and miR-146b_1 in spring viraemia of carp virus infection in common carp (Cyprinus carpio L.).

Genomic differentiation between wild Caspian Sea and Iranian farmed common carp (Cyprinus carpio) using 2bRAD-seq

Enzymatic responses in common carp (Cyprinus carpio) exposed to oxytetracycline medicated feed

Effects of enzymatic hydrolysate of black soldier fly (Hermetia illucens) in low protein diets for common carp (Cyprinus carpio): Promoting growth, enhancing antioxidant and immunity

Microbial dysbiosis induced in Cyprinus carpio by tetrabromobisphenol A exposure: Mediation through gut barrier impairment and oxidative stress.

Hypoxia and reoxygenation induced distinct patterns of response in antioxidant capacity between two cyprinid fish species.

Improving extracellular vesicle isolation from non-mammalian blood plasma: Enhancing efficiency through adjusted osmolarity.

Increasing environmental variability and fishing pressure in the Danube raise concerns about the status of common carp populations. Between 2019 and 2024, we assessed the population structure, growth, and mortality of common carp in the Romanian sector of the Danube River to evaluate its status and support sustainable management. A total of 2646 specimens (8658.29 kg) were collected using fixed and floating gillnets from representative sites along the river, and morphometric data were recorded annually, including total length, weight, and sex. Length distributions showed stable recruitment in younger classes (35–44 cm) and dominance of medium-size classes (45–64 cm), with large individuals (>70 cm) peaking in 2021. Growth and mortality parameters (L∞ = 78.75–99.75 cm, K = 0.41–1.50 year−1, Z = 1.11–2.43 year−1) represent model-derived annual estimates, obtained through standard length–frequency methods, with ranges reflecting interannual variation. Sex ratios ranged from 0.77 to 0.94 (F/M), with significant male bias in 2019 and 2021, while other years were near-balanced. Comparison with Total Allowable Catch data revealed that reported catches were often below permitted limits, exceeding 50% only in 2021 and 2023. Overall, results may suggest a resilient and moderately exploited carp population in the Romanian Danube.

Abstract Recreational fishing is a prominent leisure activity worldwide. With over 1 million participants in Hungary—approximately 10% of the total population—this widespread engagement may exert significant economic and ecological effects on aquatic ecosystems. Despite this, the potential environmental impacts associated with recreational angling had not been previously studied. Therefore, the objective of our research was to conduct a countrywide questionnaire-based survey (including 1242 angling clubs) of current management practices for angling purposes and to assess their potential environmental consequences. Responses arrived from 278 organizations, which manage 316 waterbodies (app. 25% of all). Most of them (83%) are small (< 50 hectares) artificial waterbodies, which are out of the scope of European Union level regulations. Standardized monitoring activities—i.e. fish assemblage, macroinvertebrates, etc.—were carried out only in 10–23% of them. Contrary to the low level of monitoring, 78% of fishery managers stated that they have complete knowledge of the fish assemblage composition. Although existing regulations aimed to prevent the spreading of non-indigenous species, their mean number was 4.6 ± 3. The most frequent four non-indigenous taxa occur in more than 80% of the waterbodies. Stocking is the most common (applied by 95%) management tool for prevention of overexploitation, however the number of stocked species is low (2.2 ± 1). Different age groups of Common carp ( Cyprinus carpio L., 1758) are stocked in 93% of the waterbodies, regardless of their type and natural assemblage composition. Our analyses shows that the angling club leaders’ education level significantly influences their understanding of threats to fish stocks. Those with higher, specialized education demonstrated broader knowledge of these risks, whereas leaders with less education showed limited awareness. Our study highlighted that most Hungarian angling club leaders do not have enough reliable data about the state of their waterbody. Without these, adaptive and sustainable management is impossible, especially under the pressure of global climate change and biodiversity crisis. There is an urgent need of a paradigm shift in the management practices to establish a long-term sustainable framework of recreational fishery management. Should these measures be neglected, the ecological status of angling waterbodies will degrade. leading to an increase in harmful algal blooms and fish mortalities and the expansion of non-native fish species will continue.

BackgroundSpecies belonging to the genus Argulus are globally distributed fish parasites. Their veterinary significance primarily lies in their disruptive presence and their role as mechanical vectors. Although Argulus japonicus Thiele, 1900 is a widely distributed representative of this genus that feeds on freshwater fish, only Argulus foliaceus (Linnaeus, 1758) had previously been reported in Hungary. The aim of this study was to investigate the fish louse fauna in a local common carp (Cyprinus carpio Linnaeus, 1758) population. To the best of our knowledge, this is the first study to report the occurrence of A. japonicus in Hungary.Methods and resultsOur detailed molecular analyses, including the complete mitochondrial genome, revealed for the first time that the A. japonicus specimens found in Hungary differ significantly from their Far Eastern counterparts. Furthermore, cytochrome c oxidase subunit I (cox1) sequence analysis—a region known to be stable within the species—showed that while our sequences were nearly identical to those of other European specimens, they differed markedly from the available Asian isolates. The phylogenetic analysis also confirmed this divergence. The European A. japonicus sequences form a clearly distinct sister group to the Asian lineages.ConclusionsIn light of these findings, and on the basis of thorough morphological examinations, the authors propose that the specimens found in Hungary represent a new subspecies, Argulus japonicuseuropaeus subsp. nov. Keve, 2025.Graphical