The Chinese sturgeon (Acipenser sinensis) is a critically endangered aquatic species endemic to the Yangtze River. With the expansion of artificial conservation programs, health monitoring has become critical for effective management. However, research data remain limited due to the species' rarity. Blood collection is a commonly used method for health monitoring, offering small wounds and low infection risks, but mucus sampling presents a more effective, non-invasive, and non-lethal alternative, as fish skin mucus provides key health information. This study aimed to identify health biomarkers in Chinese sturgeon and evaluate the effects of different environments on their health by combining biochemical analysis with molecular ecological methods. Eleven biochemical parameters in serum and mucus were measured, and their correlations systematically analyzed. Investigating the effects of environmental differences on mucus indicators and microbial communities of Chinese sturgeon under indoor and outdoor environmental conditions. The results indicated that alanine aminotransferase, aspartate aminotransferase, cortisol, and lysozyme levels were significantly higher in mucus than in serum, whereas alkaline phosphatase, acid phosphatase, lactic acid, lactate dehydrogenase, creatine kinase, and total protein were higher in serum. Acid phosphatase, cortisol, and lysozyme showed strong positive correlations between serum and mucus. Mucus samples from indoor-raised sturgeon exhibited higher levels of total protein, cortisol, alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase, but lower levels of lysozyme compared to outdoor-raised sturgeon. Mucus microbiota composition significantly differed between environments: outdoor microbiota was associated with nutrient catabolism, while indoor microbiota was linked to pathogenesis and microbial antagonism. This study provides baseline data on the biochemical parameters and microbiota of Chinese sturgeon, highlights environmental impacts on their health, and offers a foundation for conservation and non-invasive monitoring of this endangered species.

Chinese sturgeon; Serum; Mucus; Biochemical parameters; Microbiota; Environmental factors