Search Results (70)

Siniperca chuatsi is an important high-quality freshwater aquaculture species in China. In nature, it feeds exclusively on live food. In this study, domesticated juvenile S. chuatsi were divided into three groups and fed live food (group L), compound feed (group C), or a mixed diet (group M) for three months to investigate the molecular mechanisms underlying adaptation to compound feed. Histopathological examination revealed that compound feed consumption induced looser liver cell arrangement, hepatocyte morphological irregularities, and vacuolization. A total of 1033 and 1428 differentially expressed genes (DEGs), and 187 and 184 differential metabolites (DMs), were identified in the C vs. L and C vs. M groups, respectively. Transcriptomic analysis revealed that the significantly and commonly enriched metabolic pathways shared by both comparison groups were predominantly involved in amino acid, carbohydrate, and lipid metabolisms. Metabolomic analysis demonstrated that the significantly and commonly enriched metabolic pathways shared by both comparison groups were the arachidonic acid metabolism, linoleic acid metabolism, oxidative phosphorylation, and PPAR signalling pathways. Integrated omics analysis showed that the PPAR signalling pathway was the only significantly co-enriched pathway across both omics datasets. This study provides new insights into the molecular mechanisms of compound feed adaptation and provides theoretical support for selecting feed traits in S. chuatsi. Full article

The transition from live bait (LF) feeding to compound feed (CF) feeding in aquaculture is of great production significance. In recent decades, cultivation with CF has become a focus for practitioners and researchers dealing with Siniperca chuatsi. This study focused on experimental subjects of S. chuatsi fed with CF and LF, using short-distance transportation as a stimulating factor. For the first time, the differences between S. chuatsi fed with CF and LF were analyzed from the perspective of stress response during transportation. This study found that after transportation stimulation, the activities of LZM and the contents of MDA, TGs, and glucose in the brain, liver, kidneys, muscles, stomach, pyloric caecum, intestines, and blood of S. chuatsi fed with CF were higher compared to S. chuatsi fed with LF (p < 0.05). Significant differences were observed in the impacts of various diets on the gastrointestinal tract, particularly in the intestine. In summary, this study found that S. chuatsi fed with CF could retain more energy after transport stimulation and exhibited stronger resistance to microbial stress, but they had a weaker antioxidant capacity. Therefore, in future research on CF for S. chuatsi, we need to focus on its ability to enhance antioxidant capacity. Full article

A 56-day trial was conducted to assess the effects of rice straw (RS) and bamboo flour (BF) on growth performance, water quality, gill histology, and the bacterial community of water and the intestine of mandarin fish (Siniperca chuatsi) in biofloc technology systems. The results showed that mandarin fish in the RS and BF groups had comparable survival rates of 100.00 ± 0.00 and 93.33 ± 3.85%; feed conversion ratios of 1.13 ± 0.02 and 1.40 ± 0.15; and weight gain rates of 112.21 ± 1.56 and 100.92 ± 6.45%, respectively. From days 11 to 56 of the farming period, the BF group was more effective than the RS group in removing total ammonia nitrogen (TAN) and NO₂⁻-N, maintaining TAN levels below 0.24 ± 0.05 mg/L. During the early stage of the experiment, the TAN level in the RS group was higher; however, with the supplementation of a carbon source, it gradually decreased and eventually stabilized at 0.13 ± 0.03 mg/L later in the farming period. The secondary gill lamella in the RS group was curved and showed hyperplasia, and the basal gill lamellae showed an increase in the volume of interlamellar cell mass in the BF group. Genes related to denitrification (narG, napA, nirS, nirK, and nosZ) and anammox showed higher expression levels in the BF group than in the RS group, although the differences were not statistically significant (p > 0.05). The results of 16S rRNA sequencing research showed that both treatment groups’ intestinal and water bacterial communities had comparable levels of richness and diversity. Pseudomonas mosselii was the dominant bacterial species in the water. In the BF group, the dominant intestinal species were Bacillus halodurans and Caldalkalibacillus thermarum, while in the RS group, the dominant species was Plesiomonas shigelloides. In conclusion, rice straw and bamboo flour are applicable in BFT systems for mandarin fish culture, with good growth performance and water quality. The BF group showed higher nitrogen removal efficiency and denitrification gene expression than the RS group. Full article

Mandarin fish (Siniperca chuatsi) are known to exhibit distinct physiological and immunological adaptations to environmental stressors, but the underlying molecular and microbial mechanisms remain unclear. In this study, we integrated transcriptome and microbiome analyses to investigate adaptations across three geographically distinct mandarin fish groups: Guangdong (G), Qiupu (Q), and native Taihu (T). Liver RNA sequencing revealed 5339 differentially expressed genes (DEGs) between T and G and 1531 DEGs between T and Q. Functional enrichment analysis revealed group-specific responses. Specifically, DEGs from T vs. G were linked to small-molecule metabolism and innate immunity whereas the DEGs from T vs. Q were related to immune regulation and chromatin organization. The concurrent 16S rRNA sequencing of the intestinal microbiota identified 2680 amplicon sequence variants, with principal coordinate analysis showing distinct clustering (31.77% variance). Group T had higher Firmicutes abundance whereas groups G and Q had a higher relative abundance of Fusobacteriota. Correlation networks revealed key microbe–gene interactions, including positive links between Lactobacillus and immune genes in group T and negative associations with Romboutsia. These findings suggest that enhanced immune homeostasis and metabolic flexibility in group T may result from coordinated host gene expression and Lactobacillus-driven microbiome modulation. We provide new insights into the mechanisms of adaptation in mandarin fish and identify potential biomarkers for enhancing aquaculture resilience. Full article

An 8-week trial was conducted to investigate the effects of choline on the growth of Chinese perch (85.57 ± 0.54 g) with dietary choline supplementation at 0 (P0), 400 (P1), 800 (P2), 1600 (P3), 3200 (P4), and 6400 mg/kg (P5). Protein efficiency ratio and protein retention value (PRV) were higher in the P1–P4 groups than in the P0 group (p < 0.05). Compared to the P0 group, weight gain rate and specific growth rate (SGR) increased in the P2 and P3 groups (p < 0.05). The orexigenic gene agrp expression level rose in the P2–P4 groups (p < 0.05). The expression level of the lipolysis-related gene hsl or pparα was elevated in the P2 and P4 groups (p < 0.05). Proteolysis-related gene (ampd, mafbx, and murf1) expressions decreased in the P1–P4 groups, while tor and gk gene expressions increased in the P2 and P3 groups (p < 0.05). Broken-line analysis indicated that the optimal choline supplementation level for Chinese perch is 788.38 mg/kg based on SGR and 851.04 mg/kg based on PRV. The results demonstrate that moderate dietary choline supplementation enhances growth performance by promoting glucose and lipid catabolism and inhibiting protein catabolism in Chinese perch. Full article

Chinese perch (Siniperca chuatsi), an economically important freshwater fish in China, faces ammonia nitrogen stress under high-density aquaculture. This study investigated chronic ammonia nitrogen exposure effects on juvenile fish (95 ± 5 g) to establish safe concentration. Acute toxicity tests revealed a 96 h-LC₅₀ of 12.91 mg/L ammonia nitrogen, with a safe concentration of 1.29 mg/L ammonia nitrogen (non-ionic ammonia: 0.097 mg/L). In 28-day chronic experiments with ammonia nitrogen levels at 0, 0.61, 1.29, and 2.58 mg/L, ammonia nitrogen induced hepatic oxidative stress, with total superoxide dismutase, catalase, and glutathione peroxidase activities and malondialdehyde content increasing proportionally to ammonia nitrogen concentration initially but declining over time. Concurrently, gill Na⁺-K⁺-ATPase activity was significantly suppressed, while the gene expression of ammonia transporters (rhag, rhbg, and rhcg) exhibited ammonia nitrogen concentration-dependent upregulation, inversely correlated with the exposure duration. Histological gill damage intensified at higher concentrations. Hepatic ammonia detoxification enzymes activities (asparagine synthase, glutamine synthetase, and glutamate dehydrogenase) and glutamine accumulation increased with ammonia nitrogen levels, aligning with gene expression trends, though enzyme activity diminished over time. Serum alanine aminotransferase and aspartate aminotransferase activities and their gene expressions rose with ammonia nitrogen levels, while total protein declined. These findings demonstrate that chronic ammonia nitrogen stress disrupts antioxidant capacity, osmoregulation, and nitrogen metabolism, compelling Chinese perch to mitigate toxicity via glutamine synthesis. To ensure sustainable aquaculture, ammonia nitrogen levels should remain below 1.29 mg/L under adequate dissolved oxygen conditions. Full article

Mandarin fish (Siniperca chuatsi), golden mandarin fish (Siniperca scherzeri), and Coreoperca whiteheadi are three important aquaculture species in China facing several threats to their production. Genetic diversity was assessed by sequencing the mitochondrial D-loop and cox1 regions in 207 individuals across nine populations. The genetic diversity analysis, based on the concatenated sequences, revealed that the total haplotype diversity was high across all sinipercine fish populations. Population differentiation analysis revealed that most genetic variation was within populations: 74.5% in S. chuatsi (p < 0.001) and 83.0% in S. scherzeri (p < 0.001). All five S. chuatsi populations showed moderate and significant genetic differentiation, and moderate genetic differentiation was observed between the Beijiang and Wujiang populations in S. scherzeri. Phylogenetic and nested clade analysis indicated that artificially bred and wild S. chuatsi populations shared haplotypes, and close phylogenetic relationships were observed between the Beijiang and Dongjiang populations in S. scherzeri. These findings could be useful for the conservation management, artificial breeding, and hybridization of these three sinipercine fish species. Full article

Background: Birnaviruses infect a wide range of aquatic and terrestrial hosts, including several economically important fish species. This study aimed to isolate and characterize a novel birnavirus strain from mandarin fish (Siniperca chuatsi), a high-value freshwater species in Chinese aquaculture. Methods: A novel strain, designated mandarin fish birnavirus (MFBV), was isolated from diseased fish and propagated in SCK cells. The complete genome was determined using high-throughput sequencing and RACE. Viral replication kinetics, tissue distribution, and pathogenicity were assessed through in vitro infection, RT-qPCR, histopathology, and experimental challenges. In addition, disinfectant sensitivity and environmental stability were evaluated. Results: The MFBV genome comprises two segments (A: 3539 bp; B: 2719 bp), and phylogenetic analysis revealed close relatedness to largemouth bass birnavirus (LBBV) and Lates calcarifer birnavirus (LCBV). MFBV displayed rapid replication in SCK cells, completing a replication cycle in 8–10 h. In juvenile and fry fish, an experimental infection caused acute disease with cumulative mortality ranging from 41.8% to 83.6%, with fry showing higher susceptibility. Viral RNA was detected in multiple tissues (7.9 × 10⁶–7.9 × 10⁷ copies/μg RNA), and histopathological lesions were observed in the intestine, spleen, and kidney. MFBV was highly sensitive to glutaraldehyde (20 ppm), while other disinfectants showed reduced efficacy. Viral half-life ranged from 36.5 to 144.5 h at room temperature. Conclusions: These findings demonstrate that MFBV can induce acute systemic infection in mandarin fish. The results offer new insights into the genomic and biological features of birnaviruses, contributing to improved disease management and viral taxonomy. Full article

This study investigated the effects of dietary carbohydrate levels (control 8.13%, HG1 12.03%, and HG2 14.15%) on growth performance and glutamate metabolism in Chinese perch (S. chuatsi) (initial weight: 39.12 ± 0.25 g) reared at 12–15 °C. Diets were isonitrogenous (49% protein). After 8 weeks, the HG1 group optimized weight gain rate (WGR), specific growth rate (SGR), and protein efficiency ratio (PER), while reducing feed conversion ratio (FCR). HG1 and HG2 groups reduced liver glutamate/glutamine levels while downregulating the expression of key ammonia-metabolizing genes (gs, gdh, and ampd), collectively suppressing glutamate-mediated ammonia excretion. HG1 and HG2 groups enhanced glycolysis (upregulated gk and pk) coupled with suppressed gluconeogenesis (decreased PEPCK and G6Pase activities) in the liver. Concurrent downregulation of proteolytic markers (mafbx and murf1) in the muscle indicated improved protein conservation efficiency in the HG1 and HG2 groups. The HG1 diet optimally enhances growth by promoting glycolysis, reducing ammonia excretion, and improving feed efficiency. The insights gained from this research will be used to refine the low-temperature culture feed for Chinese perch, aiming to decrease ammonia and nitrogen emissions, thereby advancing the practice of low-ammonia emission culture for this species. Full article

Twist2 plays a pivotal regulatory role in the growth of skeletal muscle across various organisms. Nonetheless, the specific mechanism by which Twist2 governs skeletal muscle function in fish, particularly in the economically significant Chinese perch (Siniperca chuatsi), remains unclear. Within the muscle injury model in Chinese perch, we observed that Twist2 expression was upregulated during the repair phase of fast muscle tissue, exhibiting an expression pattern analogous to that of Pax7. Following the knockdown of Twist2 using Twist2-specific in vivo-siRNA in fast muscle tissues, the expression of myogenic regulatory factors (MRFs) and Myomaker was significantly reduced in the Twist2-siRNA-treated group compared with the control group, whereas no significant differences were observed for Pax3 and Pax7. Furthermore, the diameter of myofibers and the number of nuclei in single myofibers were reduced, and concurrently, the number of BrdU-positive cells (proliferating cells) was significantly reduced in the Twist2-siRNA-treated group. Taken together, this study demonstrates that Twist2 promotes myoblast proliferation and fusion, thereby regulating fast muscle growth in juvenile Chinese perch. These findings provide a clear direction for further exploration of molecular mechanisms underlying skeletal muscle growth in economic fish species. Full article

Proteins for elongation of very long-chain fatty acids (ELOVLs) are critical for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), and they are one group of the rate-limiting enzymes responsible for the initial condensation reaction within the fatty acid elongation. Elovl8 is a newly identified member of the ELOVL protein family, and its evolutionary and functional characterizations are still rarely reported. Here, we identified two elovl8 paralogues (named Scelovl8 and Scelovl8b) from Chinese perch (Siniperca chuatsi), and then their molecular and evolutionary characteristics, as well as potential roles involved in LC-PUFA biosynthesis, were examined. The ORFs of both Scelovl8a and Scelovl8b genes were 810 bp and 789 bp in length, encoding proteins of 270 and 263 amino acids, respectively. Multiple protein sequence comparisons indicated that elovl8 genes were highly conserved in teleosts, showing similar structural function domains. Meanwhile, phylogenetic analysis showed that the elovl8 gene family was clustered into two subclades of elovl8a and elovl8b, and Scelovl8a and Scelovl8b shared close relationships with banded archerfish elovl8a and striped bass elovl8b, respectively. Genetic synteny and gene structure analyses further confirmed that elovl8b is more conserved in comparison to elovl8a in teleosts. In addition, Scelovl8a was found to be highly expressed in the liver, while Scelovl8b was most abundant in the gills. Long-term food deprivation and refeeding are verified to regulate the transcription of Scelovl8a and Scelovl8b, and intraperitoneal injection of fish oil (FO) and vegetable oil (VO) significantly modified their gene expression as well. In summary, our results in this study indicate that elovl8 genes were conservatively unique to teleosts, and both elovl8 genes might be involved in the endogenous biosynthesis of LC-PUFAs in Chinese perch. These findings not only expand our knowledge on the evolutionary and functional characteristics of both elovl8 genes but also lay a solid basis for investigating regulatory mechanisms of LC-PUFA biosynthesis in various teleosts. Full article

Two typical fish products—fermented mandarin fish and semi-dried yellow croaker—are associated with biogenic amines (BAs), which are harmful to human health. The objective of this study was to investigate the bacterial ecology of the two fish products and to determine their capacity for producing BAs. Putrescine and cadaverine were major BAs detected in the fish products. Concentrations of BAs were significantly corrected with microbial count (p < 0.05). BA-producing isolates (33) in the two fish products were all multiple BA producers. Several of them, including Lactobacillus sakei, Bacillus cereus and Hafnia alvei isolated from fermented mandarin fish, as well as Shewanella baltica, Aeromonas veronii, and Photobacterium phosphoreum isolated from semi-dried yellow croaker, showed remarkable BA-producing capacity. Hafnia alvei produced the greatest abundance of putrescine, cadaverine, tyramine and 2-phenylethylamine. Lactobacillus sakei mainly produced tryptamine and putrescine. Photobacterium phosphoreum showed the strongest histamine-producing capacity. Full article

Bacterial sepsis caused by Aeromonas hydrophila (A. hydrophila) and infectious spleen and kidney necrosis virus disease (ISKNVD) caused by infectious spleen and kidney necrosis virus (ISKNV) frequently result in significant mortality among Chinese perch (Siniperca chuatsi). Co-infection of mandarin fish with A. hydrophila and ISKNV occurs from time to time. In this study, a visual detection method for ISKNV and A. hydrophila was developed, using loop-mediated isothermal amplification (LAMP) and pre-addition of hydroxynaphthol blue. Primers for amplifying LAMP in the same system were designed based on the conserved regions of the MCP gene of infectious spleen and kidney necrosis virus, as well as the hlyA gene of A. hydrophila. The results showed that this method amplified bright trapezoidal bands in the presence of only A. hydrophila or ISKNV and both, with sky blue for positive amplification and violet for negative amplification. There was no cross-reactivity with other pathogens, and fragments of 182 bp, 171 bp and 163 bp appeared after digestion of the A. hydrophila LAMP product and 136 bp, 117 bp and 96 bp appeared after digestion of the ISKNV LAMP product. This holds true even when both positive products are present simultaneously. The minimum detection limit of this method was 100 fg for A. hydrophila and 100 fg for ISKNV, and the minimum detection limit for the mixed template was 1 pg. Overall, this method has high sensitivity and specificity to rapidly detect and distinguish between the two pathogens. Full article

Fish meal (FM) replacement is essential for sustainable aquaculture development. This study investigated the effects of FM replacement with poultry by-product meal (PBM) on growth performance, hepatic and intestinal health and ammonia nitrogen stress resistance in mandarin fish (Siniperca chuatsi). A 52-day feeding trial was conducted using PBM to replace fish meal at levels of 0%, 17.5%, 35.0%, 52.5% and 70.0%. The results showed that FM replacement with PBM did not influence growth performance in mandarin fish. Moderate PBM replacement (≤35.0%) did not harm liver health and enhanced the intestinal structure. However, excessive replacement (≥52.5%) caused hepatocyte damage, reduced antioxidant capacity and decreased survival under ammonia nitrogen stress. Notably, 70% PBM replacement led to severe hepatic lipid accumulation, inhibiting fatty acid β-oxidation and triglyceride hydrolysis pathways. Furthermore, high PBM levels (≥52.5%) also reduced intestinal muscularis thickness, downregulated tight junction proteins and induced inflammation. In conclusion, while PBM replacement does not hinder growth, maintaining levels below 35.0% (PBM ≤ 28.5%) is essential for preserving hepatic lipid metabolism, intestinal health and antioxidant defense in mandarin fish. Full article

This study evaluated the habitat coloration preferences of Siniperca chuatsi and Cirrhinus molitorella in both solitary (n = 1) and group (n = 3) settings across six colors. The results indicated that both individual and group S. chuatsi spent the majority of their time in and made frequent visits to the black area, followed by the blue area. While individual C. molitorella spent the majority of their time and visits in the blue region, groups showed a preference for the blue and white regions. These findings highlight the distinct habitat coloration preferences of S. chuatsi and C. molitorella in different group states, suggesting that habitat coloration has an important effect on fish behavior and environmental adaptation. From a behavioral ecology perspective, these preferences may be closely related to the survival strategies of fish. Notably, C. molitorella’s strong preference for blue and white backgrounds may reflect anti-predator behavior, helping C. molitorella avoid predators, such as S. chuatsi, in natural environments, thereby improving its chances of survival. This study provides a scientific basis for optimizing aquaculture environments, emphasizing the importance of considering habitat coloration and substrate type in designing environments to enhance fish welfare. Full article