Impact of Composite Regulation Technology on the Ecology, Growth, and Immunity of Litopenaeus vannamei in High-Position Pond Aquaculture

To explore the optimization effects of fixed aquatic water treatment materials combined with immunomodulatory agents on the ecosystem and farming efficiency of Litopenaeus vannamei in high-water-level ponds, this study established experimental ponds (with fixed aquatic water treatment materials and feed supplemented with chitosan oligosaccharides) and control ponds (no fixed water treatment materials applied, fed with basal feed only). Through a comparative trial over a complete farming cycle, the study systematically analyzed changes in plankton community structure and diversity, water physicochemical factors, shrimp growth performance, immune indicators, and muscle nutritional composition. The results showed that in the experimental group, diatoms (Ditylum brightwellii and Skeletonema) dominated the plankton community, while the density of harmful blue-green algae (Oscillatoria and Trichodesmium) significantly decreased, and planktonic animal diversity improved in the later stages. Among the water physicochemical indicators, the experimental group exhibited a 50% reduction in nitrite levels by the later stages, significantly higher than the 33.33% reduction in the control group. Total ammonia nitrogen levels remained lower than those in the control group, with a smaller increase in the later stages. Total phosphorus levels were significantly lower in the experimental group after 80 days, and the later-stage decline in chemical oxygen demand was 11.65% higher than that in the control group. Shrimp body weight increased significantly by 13.23%, while hepatosomatic index, musculosomatic index, and immune enzyme (acid phosphatase and total antioxidant substances) activity also improved markedly. The content of unsaturated fatty acids (linoleic acid and oleic acid) in the muscles significantly increased. The study demonstrated that the combined application of fixed aquatic water treatment materials and chitosan oligosaccharide preparations can optimize the farming water environment, enhance shrimp growth performance and quality, and provide technical support for the ecological cultivation of Litopenaeus vannamei.