Hypoxia, a major issue in aquatic ecosystems, in special reference to climate change, and exacerbated by anthropogenic activities. It is causing slow growth, disease outbreaks, and mortality in finfish and shellfish. Therefore, adaptation to lowering oxygen levels through supplementation of herbs or their extracts in diets is imperative. In this study, hypoxia was simulated in controlled conditions with quercetin-enriched diets. Quercetin is a plant pigment (flavonol) possessing anti-oxidant property and is present in vegetables, leaves, seeds, pulses, and fruits. The experiment was conducted on rohu Labeo rohita, which is most widely cultured in India. There were four treatments including T1 (Normoxia: > 5 ppm dissolved oxygen; DO₂), T2 (hypoxia: 3–4 ppm DO₂), T3 (hypoxia + 50 mg quercetin/kg diet), and T4 (hypoxia + 100 mg quercetin/kg diet). The study was conducted for 30 days, and water quality was measured regularly. The results revealed that the hematological parameters were negatively affected. The tissue micro-architecture illustrated the impairment through degeneration of neurons in the brain, increased pigmentation as melanosis in the kidney, increased thickness of primary lamellae in the gills, and dilatations of sinusoids in the liver in hypoxia groups, while quercetin-enriched diets improved the hematological and histomorphological parameters. The results confirm the utility of hematological and histopathological tools as biomarkers and reflect the possible threats of hypoxia on fish. In conclusion, quercetin in diets appeared to show resistance towards chronic hypoxia by restoring the structure and functions of the vital organs towards normalcy and could be recommended as a potential ameliorative agent.

缺氧是水生生态系统的一个主要问题，特别是气候变化，并因人类活动而加剧。它导致有鳍鱼类和贝类生长缓慢、疾病爆发和死亡。因此，通过在饮食中补充草药或其提取物来适应降低氧气水平势在必行。在这项研究中，在受控条件下用富含槲皮素的饮食模拟缺氧。槲皮素是一种具有抗氧化特性的植物色素（黄酮醇），存在于蔬菜、叶子、种子、豆类和水果中。该实验是在印度饲养最广泛的南亚野鲮（Labeo rohita）上进行的。有四种治疗方法，包括 T1（常氧：> 5 ppm 溶解氧；DO ₂）、T2（缺氧：3–4 ppm DO ₂）、T3（缺氧 + 50 mg 槲皮素/kg 饮食）和 T4（缺氧 + 100 mg）槲皮素/公斤饮食）。研究进行了30天，并定期测量水质。结果显示血液学参数受到负面影响。组织微结构表明，缺氧组的大脑神经元退化、肾脏黑变病等色素沉着增加、鳃初级板层厚度增加以及肝脏血窦扩张而造成损害，而富含槲皮素的饮食则改善了这一情况。血液学和组织形态学参数。结果证实了血液学和组织病理学工具作为生物标志物的效用，并反映了缺氧对鱼类可能的威胁。总之，饮食中的槲皮素似乎可以通过将重要器官的结构和功能恢复正常来表现出对慢性缺氧的抵抗力，可以推荐作为潜在的改善剂。