To explore a safe and effective approach for producing strontium-enriched fish, in this study, we modified the feed for juvenile hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂) and set three different levels of strontium chloride content in their diet (0 mg/kg (Sr0, control), 80 mg/kg (Sr80), and 160 mg/kg (Sr160)) for a period of 8 weeks, analyzing their growth performance, strontium enrichment, muscle nutrition, and hepatic physiological, biochemical, and transcriptomic characteristics. The results show that dietary strontium had no significant impact on sturgeon growth or survival rate (p > 0.05). The strontium content in tissues increased with dietary strontium levels, with the highest enrichment in bone plates (p < 0.05). However, muscle crude fat in the strontium-supplemented groups decreased significantly; the Sr160 group had higher glutamic acid, valine, docosahexaenoic acid methyl ester, lower myristic acid, palmitic acid, etc. (p < 0.05). In addition, strontium treatment alleviated hepatic lipid accumulation and mitochondrial swelling. Biochemical analyses revealed reduced plasma levels of Triglyceride (TG), Total Cholesterol (TC), Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST), as well as decreased hepatic Malondialdehyde (MDA) content, while hepatic Glutathione (GSH) levels increased (p < 0.05). Transcriptomic data further showed that strontium downregulated the expression of fasn and tfrc and upregulated the expression of cpt1a, apoa1, cyp7a1, and slc3a2 (p < 0.05). In conclusion, dietary supplementation with 80–160 mg/kg strontium enables safe strontium enrichment in hybrid sturgeon, improves muscle nutritional quality, and protects liver function by regulating the genes related to lipid metabolism and antioxidant defense, providing a scientific basis for the development of strontium-enriched fish products.

Sichuan bream (Sinibrama taeniatu), an endemic small economic fish in the upper Yangtze River, has achieved captive breeding breakthroughs. To advance standardized and large-scale aquaculture, this study investigated intestinal development, enzyme activities, gut microbiota, and its interactions with rearing water microbiota across six developmental stages (G1–G6) from hatching to sexual maturity of Sichuan bream. Results showed its progressive refinement of external morphology and intestinal developing into multiple flexures. Histology examination revealed four foregut layers with continuously increasing villus height. Digestive enzyme analysis revealed significantly higher activity of trypsin compared to that of amylase and lipase (p < 0.05). 16S rRNA sequencing identified Proteobacteria, Firmicutes, Bacteroidota, Actinobacteriota, and Fusobacteria as the dominant phyla in both gut and rearing water microbiota. Gut communities shifted from Proteobacteria-dominance (C₁–C₅) to Firmicutes-dominance (C6). The microbial source tracking analysis indicated water contributed to gut microbiota of Sichuan bream, particularly during G3. This study clarified the intestinal development patterns and gut microbiota colonization dynamics of Sichuan bream. The findings provide reference materials for the research on the growth patterns and host–microbe interaction of Sichuan bream. They lay a theoretical foundation for the protection and utilization of Sichuan bream resources, ultimately aiding in their proliferation and release.

Sperm cryopreservation is pivotal for conserving fish germplasm, yet cryodamage-induced quality decline limits its application. This study focused on Sichuan bream (Sinibrama taeniatus), an endemic and economically important fish species in the upper Yangtze River. Based on an established cryopreservation protocol, we evaluated sperm quality using computer-assisted sperm analysis (CASA) and fertility assays, followed by a systematic assessment of structural and functional damage via flow cytometry (membrane integrity, mitochondrial potential, reactive oxygen species, and DNA fragmentation), enzymatic assays (energy metabolism and antioxidant enzymes), Western blotting, and ultrastructural observation. Finally, integrated proteomic and metabolomic analyses were employed to elucidate the underlying physiological mechanisms. The results demonstrated that freeze–thawing significantly impaired sperm motility, fertility, and ultrastructure, concurrently disrupting energy metabolism and the antioxidant system. Crucially, multi-omics revealed that these functional declines were linked to dysregulation in key pathways involving cytoskeleton organization, lipid metabolism, energy homeostasis, and oxidative stress, forming a coherent network from initial molecular perturbation to phenotypic dysfunction. This study provides a comprehensive characterization of sperm cryodamage in Sichuan bream, advancing the understanding of fish sperm cryobiology and informing targeted cryoprotection strategy development.