Synergistic efficacy of astragalus polysaccharides and chitosan in treating Aeromonas veronii infections in saline-alkaline water-cultured nile tilapia (Oreochromis niloticus): integrating early bactericidal and long-term immunoregulatory effects - Huijie Chen; He Kang; Yanhua Liu; Xinyuan Ye; Yaya Chen; Daoquan Ren; Zhulan Nie; Wentao Zhu (Fish & Shellfish Immunology, 2026)