The present study aimed to systematically investigate the underlying differences in flesh quality between wild and farmed Monopterus albus. Fifteen healthy M. albus per group with an average body weight of 45 g were sampled to analyze muscle parameters by biochemical indicators, histomorphology, and molecular biology. Compared with the wild fish, the farmed M. albus in flesh had lower crude protein, collagen, lysine, histidine, total amino acids, SFA, n-3 PUFA contents, and n-3/n-6 ratio (p < 0.05), and higher moisture, crude lipid, crude ash, MUFA, n-6PUFA, and total PUFA contents (p < 0.05). The thawing loss, drip loss, steaming loss, and boiling loss in the farmed group were significantly higher, and hardness, springiness, cohesiveness, gumminess, chewiness, and resilience were significantly lower than those in the wild group (p < 0.05). In addition, higher muscle fiber density and lower muscle fiber diameter were observed in wild M. albus (p < 0.05). In muscle transcriptome profiling, differentially expressed genes and enriched pathways are primarily associated with muscle development, protein synthesis, catabolism, lipid metabolism, and immunity. To the best of our knowledge, this is the first investigation that compares the flesh quality between wild and farmed M. albus in terms of biochemistry, histology, and molecular biology levels. Overall, wild M. albus had a higher nutritional value and texture quality than farmed M. albus.

As consumer demand for quality fish products continues to rise, quality has become a key factor in market competition. Ecological aquaculture research is exploring various farming methods to balance high-quality demand with environmental protection. This study compared three aquaculture models—cage culture (CG), recirculating aquaculture (RAG), and rice–fish co-culture (RG)—by analyzing muscle quality (AOAC, GC-MS), intestinal microbiota (16S rRNA), and liver metabolism (LC-MS) to assess their effects on M. albus. In terms of muscle quality, the RG group showed increased levels of EPA and DHA, reduced muscle moisture and crude lipid content, and enhanced crude protein accumulation. The crude protein content was significantly higher in the RAG group than in the CG group (p < 0.05). The RG group also had the highest levels of total, essential, and umami amino acids, followed by the RAG and CG groups. In terms of intestinal microbiota, the RG group had the highest microbial diversity and stability, with increased abundance of Firmicutes and Bacteroidetes and decreased levels of Proteobacteria. Compared to the CG, the RAG group also showed increased microbial diversity and a reduction in pathogenic genera. Liver metabolomics analysis demonstrated that the RG group had significant advantages over the CG group in amino acid, lipid, and energy metabolism. The RAG group exhibited upregulation of glycerophospholipid metabolism and a decrease in oxidative stress marker levels. Overall, the RG group enhanced muscle quality and optimized intestinal and liver metabolism in M. albus.

This study aimed to evaluate the impact of substituting a portion of feed with Tenebrio molitor (TM) and Elodea nuttallii (EN) on crayfish culture. A total of 270 crayfish (5.1 ± 0.4 g) were fed three different diet combinations (A: 100% feed; B: 80% feed + 10% TM + 10% EN; C: 75% feed + 15% TM + 10% EN) for 12 weeks. The findings demonstrated that group C had an important beneficial impact on the growth performance of crayfish. This was evidenced by a rise in digestive enzyme activity (trypsin, lipase, and cellulase) in the intestinal and hepatopancreas, as well as an upregulation in the expression of growth-related genes (ghsr, igfbp7, mhc, mlc1, mef2, and pax7) in the muscle. Furthermore, the assessment of the flesh quality of crayfish muscle in group C was conducted. The findings indicated a significant increase (p < 0.05) in the energy value (moisture, crude protein, and crude lipid) within the muscle. The levels of delicious amino acids (Glu, Ala, Ser, Gly, and Tyr) and polyunsaturated fatty acids (ARA, DHA) were enhanced, resulting in an improved nutritional profile and flavor of the muscle while maintaining the Σn-3/Σn-6 ratio. The remodeling of the intestinal microbiota (abundance of Proteobacteria and ratio of Firmicutes/Bacteroidota bacteria) also revealed improved growth performance. Additional research is necessary to ascertain whether excessive use of TM or EN feed substitution can have negative effects on crayfish culture.

To investigate the dietary effects of chlorogenic acid (CGA) on the growth performance, lipid metabolism, antioxidant activity, and non-specific immunity of Asian swamp eel (Monopterus albus) during the domestication stage, a 28-day feeding experiment was conducted to supplement with CGA at levels of 0 (Cont.), 250 (CGA 0.50%), 500 (CGA 1.00%), and 750 (CGA 1.50%) mg/kg·bw by feeding with yellow mealworm (Tenebrio molitor). Compared with the control group, the addition of 250–750 mg/kg of CGA significantly increased the weight-gain rate (WG) of M. albus, and the CGA 1.0% group displayed the highest value. The content of hemoglobin and high-density lipoprotein in all CGA groups was markedly elevated (p < 0.05), while the triglyceride, glucose, low-density lipoprotein, and glycosylated serum protein levels were lowered (p < 0.05). Among the antioxidant enzymes, the glutathione peroxidase and catalase activity was significantly higher in all experimental groups than that of the control group, whereas the malondialdehyde activity was significantly reduced (p < 0.05). For a non-specific immune enzyme system, the lysozyme and alkaline phosphatase activity in all treatments and the superoxide dismutase and acid phosphatase activity in the CGA 0.5% group was markedly increased (p < 0.05). In conclusion, supplementation with CGA can enhance the growth performance and improve the lipid metabolism, antioxidant capacity, and non-specific immunity of M. albus during the domestication stage, and the optimal CGA supplementation for T. molitor as biocarrier bait is 500 mg/kg, corresponding to 405 mg/kg.

The Asian eel, a medicinal and edible species, lacks systematic research on age-related nutritional and flavor dynamics. To optimize breeding strategies and product differentiation, this study systematically investigated the nutritional composition, flavor profiles, and physical properties of Asian eel muscles across five distinct growth stages (1, 3, 7, 11, and 22 years). Results showed that unsaturated fatty acids increased with age, while ω-3/ω-6 ratios peaked in 1-year-old eels. The levels of hydrolyzed essential amino acids were higher in the 3–11-year-old groups, contrasting with higher free amino acids in 1- and 22-year-old eels. Texture declined in hardness/chewiness but improved in resilience with age, linked to muscle fiber density and diameter. One–three-year-old eels exhibited compact muscle fibers and superior texture, while 7–22-year groups demonstrated functional lipid profiles (high docosahexaenoic acid and γ-aminobutyric acid, low cholesterol). These findings highlight age-specific quality traits: 1–3-year-old eels are suitable for fresh consumption, 3–11-year groups offer bioactive benefits, and 22-year-old eels serve as premium functional ingredients. The study provides a scientific basis for targeted breeding and market segmentation to enhance the value of eel aquaculture.