Aquatic hypoxia is a frequent event and a complex set of physiological and biochemical alterations are employed to cope with this environmental stress in fish. This study aimed at evaluating the protective effects of Sargassum horneri on hypoxia stress in black sea bream Acanthopagrus schlegelii. Four hundred and eighty fingerlings with approximate mean body weight of 12.0 ± 0.1 g were randomly distributed into four experimental groups in triplicate. Each group was stocked with 40 fish and fed with isonitrogenous (42% crude protein) and isolipidic (12% crude lipid) experimental diets containing either 0% (control), 3%, 6%, or 9% S. horneri in the feed. At the end of 8 weeks of experimental feeding, fish were exposed to hypoxia (dissolved oxygen 2.5 mg L⁻¹) conditions for 12 h and subsequent recovery to normoxia (dissolved oxygen 7.2 mg L⁻¹). Fish samples were collected after hypoxia stress at 0, 6, 12 h, and 12 h recovery to normoxia, respectively. Hypoxia stress caused a significant increase in the serum concentrations of cortisol, glucose, and lactate at 6 h after hypoxia, as well as the activities of hepatic superoxide dismutase (SOD) and MDA content at 12 h after hypoxia compared with 0 h after hypoxia. Moreover, the fish exhibited a significantly higher level in the mRNA expressions of hepatic Cu/Zn-SOD, HSP70, and HSP90 at 12 h after hypoxia. However, dietary S. horneri supplementation could significantly improve antioxidant capacity and resistance against hypoxia stress, particularly in the 6% S. horneri group. Therefore, the optimal dietary S. horneri level based on increasing the resistance of hypoxia for juvenile black sea bream in the present study was estimated to be approximately 6% dry diet.

水生缺氧是一个经常发生的事件，需要采用一系列复杂的生理和生化改变来应对鱼类的这种环境压力。本研究旨在评估羊栖藻对黑鲷刺A（Acanthopagrus schlegelii）的低氧胁迫的保护作用。将四百八十只平均体重为12.0±0.1克的鱼种随机分为四个实验组。每组饲养40条鱼，并饲喂含氮0％（对照），3％，6％或9％的角。的等氮（42％粗蛋白）和异脂（12％粗脂质）实验饲料。 。在实验喂养的8周结束时，鱼暴露于缺氧状态（溶解氧2.5 mg L^-1）条件下保持12小时，随后恢复至常氧状态（溶解氧7.2 mg L ^-1）。缺氧应激分别在0、6、12 h和12 h恢复至常氧后收集鱼样品。缺氧应激导致缺氧后6 h的血清皮质醇，葡萄糖和乳酸盐的浓度显着增加，缺氧后12 h的肝脏超氧化物歧化酶（SOD）和MDA含量高于缺氧后0 h。此外，在缺氧后12 h，该鱼肝Cu / Zn-SOD，HSP70和HSP90的mRNA表达水平显着升高。然而，日粮中添加霍尼酵母可以显着提高抗氧化能力和对缺氧应激的抵抗力，尤其是在6％S. horneri组。因此，在本研究中，基于增加对幼年黑鲷的低氧抵抗力的最佳日粮S. horneri估计约为干饮食的6％。