Search Results (33)

Zinc (Zn) is an essential trace element that plays important roles in growth, digestion, antioxidant defense, immunity, and inflammation regulation in fish. This study investigated the effects of graded dietary Zn levels on growth performance, serum biochemistry, digestive enzyme activity, zinc transporter expression, antioxidant capacity, immune responses, and inflammatory regulation in juvenile black carp (Mylopharyngodon piceus). Six isonitrogenous and isoenergetic diets were formulated to contain 27.95, 34.38, 44.90, 66.52, 116.14, and 199.56 mg/kg Zn by supplementing ZnSO₄·7H₂O. Juvenile fish with an initial weight of 2.88 ± 0.12 g were fed the experimental diets for 60 days in triplicate tanks. Growth performance increased with dietary Zn and then plateaued at 44.90–199.56 mg/kg; broken-line regression estimated the optimal dietary Zn requirement at 44.6 mg/kg. Adequate Zn supplementation also reduced whole-body lipid content, increased digestive enzyme activities, improved serum HDL-C and ALP levels, and decreased AST and ALT activities. In addition, adequate dietary Zn (44.90 mg/kg) significantly modulated the expression of zinc transporter genes in the liver and intestine. Adequate dietary Zn supplementation enhanced antioxidant capacity by activating the Nrf2/Keap1 signaling pathway, improved intestinal immunity, and strengthened barrier function by increasing the expression of tight junction proteins and mucins. Moreover, adequate dietary Zn could alleviate inflammatory responses by upregulating anti-inflammatory factors and downregulating pro-inflammatory cytokines via the MAPK14 signaling pathway. These findings suggest that dietary zinc at 44.60 mg/kg is sufficient to promote growth, antioxidant status, immune function, and intestinal health in juvenile black carp. Full article

Background: Dietary protein optimization is an important nutritional strategy for improving growth and physiological responses, and antioxidant homeostasis in fish. Methods: In this study, 540 black carp (initial body weight: 10.50 ± 1.00 g) were randomly assigned into recirculating tanks (500 L) fed with six dietary protein levels (30–44% crude protein) for an 8-week feeding trial with triplicates per treatment and 30 fish per replicate. After the trial, fish body, blood, hepatopancreas, and intestinal samples were collected for body composition, serum biochemical parameters, metabolism, and antioxidant indices’ analyses. Results: Results showed fish fed 38% protein (PT38) exhibited the highest weight gain (p < 0.05), with no further improvement at higher protein levels. Compared with PT30 group, PT38 group significantly promoted protein deposition by upregulating transcript levels of insulin-like growth factors (IGFs) via activating mechanistic target of rapamycin (mTOR) signaling pathway. PT38 could improve fatty acid oxidation by heightening levels of carnitine palmitoyl transferase 1α (CPT1α), peroxisome proliferator-activated receptor α (PPARα) and PPARδ. Meanwhile, PT38-PT41 significantly inhibit expression of fatty acid synthesis and lipid droplet deposition-related genes, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and perilipin 2 (p < 0.05). PT38 significantly enhanced antioxidant homeostasis by increasing levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) via activating nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Conclusions: Overall, Under the current experimental conditions, 38% dietary protein is suitable for promoting growth performance, improving protein and lipid metabolism, and enhancing antioxidant homeostasis in black carp. Full article

A new species of shoveljaw carp, Scaphesthes zhejiangensis, is described from the Qiantang River basin and three independent rivers in Zhejiang Province, Southeast China. It is distinguished from other Scaphesthes species by the following combination of characteristics: a long, slender body (depth 19.9–22.2% SL); 46–49 lateral-line scales; 15–17 pre-dorsal scales; a short head (depth 66.8–73.3% HL); a wide mouth (width 36.2–45.3% HL); elongated maxillary barbels shorter than one-third of the eye diameter; reduced but visible rostral barbels; a slender, smooth last simple dorsal ray; and the absence of a longitudinal black stripe along the lateral line. Molecular phylogenetic analysis based on the mitochondrial cytochrome b (cyt b) gene supported the monophyly of S. zhejiangensis sp. nov., which formed a clade with S. virgulatum, S. macrolepis, and the S. barbatum species complex. Full article

The aim of this study was to evaluate the effects of incorporating Black Soldier Fly Meal (BSFLM) into the diet of two-year-old carp on growth and health status. Four concentrations of BSFLM were tested, T1-0% (control), T2-10%, T3-20%, and T4-30%, in common carp with an initial body weight of 112.06 ± 3.86 g over a 12-week feeding period. The results showed that final weight and weight gain were 17.3% (349.15 g) and 23% (233.6 g) higher in the T4 group compared to the control (298.63 g and 189.79 g, respectively). Flesh composition showed no significant changes. Hematological variations were insignificant. Oxidative stress assessment revealed increased activities of antioxidant enzymes (SOD, CAT, and GPx) alongside reduced lipid peroxidation. The counts of anaerobic microorganisms and Enterobacteriaceae in intestine increased linearly in BSFLM groups. Histological examination showed normal intestinal and hepatopancreatic morphology in the 10% and 20% BSFLM groups (T2 and T3). In contrast, the 30% inclusion level (T4) was associated with hepatocellular vacuolization and alterations in villus architecture. In two-year-old carp, dietary BSFLM induced dose-dependent responses, whereby higher inclusion levels supported weight gain but adversely affected the morphological integrity of the intestine and hepatopancreas. Full article

The black carp (Mylopharyngodon piceus) is an ecologically and economically important freshwater fish native to China and neighbouring regions, but its wild stocks have declined sharply in recent decades. We analysed mitochondrial cytochrome b (Cyt b) sequences from 100 individuals collected in 2008–2009 from four Yangtze River, two Pearl River and one Red River populations to assess genetic diversity and structure as a pre-ban baseline for maternal lineages. Sixteen polymorphic sites defined 17 haplotypes, with a single dominant haplotype (Hap2) shared across all populations. Haplotype diversity was high but nucleotide diversity low, and neutrality tests together with mismatch-distribution analyses were consistent with a recent Late Pleistocene demographic expansion. Pairwise FST values ranged from negligible differentiation among middle–lower Yangtze populations to pronounced differentiation between the upstream Yangtze population (SS) and middle–lower populations and between the Yangtze and the combined Pearl–Red basins, whereas Pearl and Red River populations showed no significant divergence and high mitochondrial homogeneity, consistent with substantial historical connectivity. Overall, the Cyt b data indicate low mitochondrial diversity and shallow but significant inter-basin structuring, providing preliminary mtDNA-based evidence that Yangtze and Pearl–Red populations represent candidate conservation and management units, and highlighting the need for nuclear genomic markers and contemporary sampling to refine drainage-scale units and evaluate recent management effects. Full article

Frass is the by-product of the larval meal industry and consists of leftover feed materials, exoskeleton shedding, and larval excrement of black soldier fly larvae (BSFL). To assess the impact of dietary frass (BSFLF) on the growth, feed consumption, biochemical indices, whole-body proximate composition, serum biochemical indices, and fatty acid composition (hepatopancreas) of common carp (Cyprinus carpio), an 8-week study was carried out. Juveniles were fed diets with different inclusion of BSFLF levels (0%, 10%, and 20%) in a recirculating aquaculture system, with each diet randomly assigned to a triplicate group of 90 fish (10 fish per tank), with an initial weight of 119.35 ± 30.97 g stocked into 250 L tanks. The study found that increasing dietary frass led to increased growth rates, relative growth rate, weight gain, and protein efficiency ratios, and to decreased feed conversion ratios. Within both total phospholipid and triglyceride fatty acid compositions, the 20% dietary frass increased proportions of saturated and omega-3 fatty acids while decreased the oleic acid (C18:1n9) proportion. To sum up, the use of BSFLF, notably at a 20% inclusion level, as a source of dietary protein has the potential to significantly improve the overall productivity of common carp. Full article

The middle reaches of the Yangtze River are a crucial breeding habitat for four major Chinese carps. The ecohydrological characteristics of their spawning grounds are crucial factors influencing spawning for these species: black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Aristichthys nobilis). To investigate the impact of ecohydrological processes within the Three Gorges Reservoir on spawning, this study focused on the spawning grounds of the four major Chinese carps in the Yichang–Yidu section of the Yangtze River. By identifying key ecohydrological indicators and leveraging hydrological and spawning monitoring data from 2013 to 2024, the response characteristics of the four major Chinese carps’ spawning to these hydrological processes were analyzed. The results showed that the key ecohydrological indicators currently stimulating spawning for the four major Chinese carps are the fish-perceived daily flow rate increase, the fish-perceived cumulative flow rate increase, and the daily flow rate increase. These three indicators are significantly positively correlated with the scale of spawning for the four major Chinese carps. The thresholds for spawning at least 20% of the annual spawning total are: a perceived daily flow increase (P_da) of 4.52–36.05%; a perceived cumulative flow increase (P_cu) of 36.15–180.23%; and a daily flow increase (Q_av) of 588–2825 m³/s. The optimal water temperature for the reproduction of the four major Chinese carps is 21–23 °C. Overall, since the Three Gorges Reservoir’s normal operation, the frequency and scale of spawning for the four major Chinese carps have been highest during periods of rising water. It is recommended that, within the corresponding thresholds, ecological operation be conducted twice a year, once in mid-June and once in early July or late June. Daily flow increases can be controlled within the range of 588–2000 m³/s. This study analyzed the correlation between eco-hydrological indicators and the stimulation of spawning of the four major Chinese carps, providing optimized flow ranges and habitat conditions for ecological operation, which is conducive to promoting the reproduction and spawning of the four major Chinese carps in the Yichang–Yidu spawning grounds in the middle reaches of the Yangtze River. Full article

The use of insects for feed has a significant impact on aquaculture, contributing to the achievement of the Sustainable Development Goal of Zero Hunger and Sustainable Agriculture (SDG 2), among others. This study mapped the intermediate Technology Readiness Levels (TRLs), encompassing scientific knowledge (TRL 3) through 971 scientific articles (Scopus) and technological development (TRLs 4–5) through 218 patents (Espacenet). The highest conversions from TRL 3 to TRLs 4–5 were observed for fish, mollusks, crustaceans, and annelids. Key technological targets include carp and black soldier flies (BSF). Most technologies follow circular economy principles. Emerging themes include immunity, cloning, molecular techniques, metabolomics, and genetics. China leads in TRLs 3–5, followed by the United States. Only France, the United States, and five additional countries hold export-oriented patents targeting 26 markets, primarily involving BSF-based feed formulations. Future growth trends are exponential for scientific articles, logarithmic for total patents, and linear for export patents. Collaboration at TRLs 4–5 remains limited, underscoring the need for greater international cooperation to expand access to sustainable insect-based aquaculture feed technologies. Full article

Oujiang color common carp display four striking varieties of pigmentation, but their epigenetic basis is unclear. We integrated genome-wide DNA methylation (MBD-seq) and transcriptomes (RNA-seq) from dorsal skin of four Oujiang color common carp varieties with three biological replicates. Black-spotted groups (RB, WB) showed approximately 6% higher global methylation than non-black-spotted groups (WR, WW), with differential methylation enriched in introns (>23%) and intergenic regions (>47%). Integrative analyses revealed a strong inverse association between promoter methylation and gene expression; 96 pigmentation-related genes were identified, spotlighting genes such as ASIP and frmA as key epigenetically silenced regulators in black-spotted carp. RT-qPCR confirmed directional concordance with RNA-seq for ASIP, frmA, DGAT2, SCARB1, and FOSB. Pathway enrichment implicated melanogenesis metabolism, tyrosine metabolism, lipid metabolism, and fatty acid metabolism, suggesting an interplay between pigment deposition and metabolic regulation. Collectively, the findings present an exploratory view of epigenetic control of coloration and underscore promoter methylation as a core layer influencing color diversity in Oujiang color common carp. Full article

Fish-derived collagen can reduce the risk of disease transmission and has no religious or cultural restrictions. However, it has limited applications due to its poor thermal stability. In this study, black carp swim bladder collagen (BBC), classified as a type I collagen, was extracted. Amino acid composition analysis revealed that BBC had a higher proline hydroxylation rate of 39.57%. Fourier transform infrared spectroscopy revealed that BBC exhibited a complete triple-helix structure. The fractional viscosity curve and differential scanning calorimetry curves revealed that the thermal denaturation temperature (Td) and the melting temperature (Tm) were 30.85 °C and 107.19 °C, respectively. The dynamic rheological analysis showed that as the concentration increased from 5 mg/mL to 20 mg/mL at 0.01 Hz, the storage modulus increased from 0.979 Pa to 84.2 Pa. When the temperature exceeded the Td, the BBC solution exhibited viscous behaviour as the frequency increased. The steady-shear analysis showed that the BBC was a shear-thinning fluid. Functional properties analysis revealed that BBC exhibited better emulsification properties, foaming properties, water absorption capacity and oil absorption capacity than land-derived collagen, making it suitable for emulsifiers, bubbling beverages, and frozen meat preservation. Additionally, BBC promoted the growth of MT3C3-E1 cells and maintained the normal morphology of the cells. These results showed that BBC is a promising substitute for terrestrial collagen in functional foods, cosmetics, and biofunctional materials. Full article

This research investigated the growth, serum biochemistry, antioxidant capability, and immunity impact of black carp fed degossypolled cottonseed protein replacing fishmeal at the levels of 0%, 10%, 20%, 30%, 40%, and 50% (DCP0, DCP10, DCP20, DCP30, DCP40, and DCP50), respectively. The results showed there were no significant changes in growth among these test groups. The activities and mRNA expression levels of amylase and trypsin were heightened in conjunction with 30–40% DCP. Although the insulin contents were reduced with a rise in DCP content, 5-hydroxytryptamino was increased in the DCP40 and DCP50 groups. DCP40 could heighten the levels of low-density lipoprotein cholesterol, triglycerides, total cholesterol, and urea nitrogen. Although lower levels of DCP (≤20%) could increase the total antioxidant capacity compared with the DCP50 group, DCP50 could markedly heighten levels of catalase, glutathione S-transferase, H₂O₂, and malondialdehyde. Meanwhile, the mRNA levels of Mn-superoxide dismutase, glutathione reductase, glutathione peroxidase, glutamate–cysteine ligase regulatory subunit, and nuclear factor E2-related factor 2 were heightened in the DCP30 group compared with the DCP50 group. The levels of alkaline phosphatase, immunoglobulin M, and liver-expressed antimicrobial peptide 2 were markedly heightened in the liver of the DCP20 group compared with the DCP50 group. In conclusion, a suitable level of DCP (20%) could improve serum biochemical indices and hormone variation, enhance antioxidant capability, and increase immunity in black carp. Full article

Flow velocity is a critical factor in determining the suitability of fish habitats. Understanding the preference patterns of the four major Chinese carps (FMCCs) for different flow velocities is crucial for their habitat conservation and restoration. In this study, the preference of individual fish species, approximately 15 cm in length, for flow velocity was investigated at flow velocity gradients of 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0 times their body length. Additionally, a deep learning algorithm based on convolutional neural networks (CNNs) was employed for fish target detection. The results showed that, at this length, black carp (Mylopharyngodon piceus) preferred fast currents when the inlet flow velocity was between 0.4 and 1.6 times their body length, while grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Hypophthalmichthys nobilis) preferred fast currents when the inlet flow velocity of the test flume was between 0.4 and 2.0 times their body length. However, this preference for fast currents decreased as the overall flow velocity increased to a specific threshold, eventually leading to their avoidance. The highest preference for fast currents among the four species was observed at inlet flow velocities of 1.2, 0.4, 0.8, and 0.8 times their body length, respectively. The findings of this study provide important insights into habitat conservation and restoration for the FMCCs in projects focused on the construction of navigation channels and water conservancy. Full article

Background: Amoxicillin (AMOX) is widely used in aquaculture for bacterial infections due to its efficacy and safety. Despite official approval for select species, off-label use is common. This study evaluated the antibacterial efficacy and residue depletion of AMOX in five aquaculture species: olive flounder (Paralichthys olivaceus), rainbow trout (Oncorhynchus mykiss), Japanese eel (Anguilla japonica), black rockfish (Sebastes schlegelii), and Israeli carp (Cyprinus carpio). Methods: Fish were administered AMOX orally at 40 mg/kg and 80 mg/kg for seven days. Antibacterial efficacy was assessed by bacterial load reduction and survival rates following artificial infection. Residue depletion was analyzed using HPLC–MS/MS to determine the time required for AMOX levels to fall below the maximum residue limit (MRL, 0.05 mg/kg). Results: AMOX, at 40 mg/kg, significantly reduced bacterial loads in olive flounder, rainbow trout, and Japanese eel (p < 0.05), while Israeli carp exhibited a limited response (p = 0.54). Black rockfish showed moderate efficacy (RPS 72.7%) but increased mortality at 80 mg/kg. Residue levels fell below the MRL within 10 days for all species except Israeli carp (~30 days). Conclusions: These findings highlight species-specific differences in AMOX efficacy and residue depletion rates, emphasizing the necessity of tailored dosing regimens and withdrawal periods to ensure optimal therapeutic outcomes and food safety compliance in aquaculture. Further pharmacokinetic studies are needed to refine dosing strategies, particularly for species with extended residue retention and potential dose-dependent adverse effects. Full article

Fish need to make different responses to different water flow conditions, as a variety of fish utilize or overcome the water flow while fish are in the water. This study aims to analyze the response of two types of carp (black carp and silver carp) to water flow in different body lengths (2.0–10.0 cm) in early developmental stages in an open channel. By analyzing the water velocity and fish swimming behavior, swimming against the water flow was the most frequent swimming behavior, and the frequencies of this behavior increased with the increased body length of fish. The results demonstrated that the detectable water velocity of two carp species of different body lengths remained in a certain range (0.020–0.060 m/s). Black carp and silver carp can swim against the water flow of 0.295–0.790 m/s and 0.245–0.825 m/s, respectively. The results of this study can provide invaluable data for engineers and biologists to protect fish in the early developmental stage and restore the ecological habitats in the regulated river systems. Full article

This study investigated the effects of dietary erucic acid (EA) on growth, lipid accumulation, antioxidant and immune abilities, and lipid metabolism in black carp fed six diets containing varying levels of EA (0.00%, 0.44%, 0.81%, 1.83%, 2.74%, and 3.49%), for 8 weeks. Results showed that fish fed the 3.49% EA diet exhibited lower weight gain, compared to those fed the 0.81% EA diet. In a dose-dependent manner, the serum triglycerides and total cholesterol were significantly elevated in the EA groups. The 1.83%, 2.74%, and 3.49% levels of EA increased alanine aminotransferase and aspartate aminotransferase activities, as well as decreased acid phosphatase and alkaline phosphatase values compared to the EA-deficient group. The hepatic catalase activity and transcriptional level were notably reduced, accompanied by increased hydrogen peroxide contents in the EA groups. Furthermore, dietary EA primarily increased the C22:1n-9 and C20:1n-9 levels, while decreasing the C18:0 and C18:1n-9 contents. In the EA groups, expressions of genes, including hsl, cpt1a, cpt1b, and ppara were downregulated, whereas the fas and gpat expressions were enhanced. Additionally, dietary EA elevated the mRNA level of il-1β and reduced the expression of il-10. Collectively, high levels of EA (2.74% and 3.49%) induced lipid accumulation, reduced antioxidative and immune abilities in black carp by inhibiting lipid catabolism and increasing lipogenesis. These findings provide valuable insights for optimizing the use of rapeseed oil rich in EA for black carp and other carnivorous fish species. Full article