Effects of the dietary therapeutic dose of oxytetracycline (OTC) at 80 mg/kg biomass/day for consecutive 10 days on the behaviour, feed intake, mortality, residue accumulation and depletion, antioxidant capacity and immune-related genes expression in juvenile Nile tilapia Oreochromis niloticus were evaluated. OTC-dosing caused mortalities, reduced feed intake, and biomass reduction at 24.5–28.5 °C. OTC residues recorded on day 10 (161.40 ± 11.10 ng/g) were within the maximum residue limits of the Codex Alimentarius. The withdrawal period was 7 days as per the European Commission's regulation. Traces of residues were present even on day 42 post-OTC-dosing. Dietary OTC reduced the antioxidant capacity of the liver and muscle tissues and down-regulated the expression of tumour necrosis factor-α, interleukin-1β, and heat shock protein-70 genes in the liver significantly during the dosing period. The data generated on the biosafety of OTC-dosing may offer inputs for the development of management strategies in maintaining fish health and food safety.

土霉素（OTC）的日粮治疗剂量为 80 mg/kg 生物量/天，连续 10 天对尼罗罗非鱼Oreochromis幼鱼的行为、采食量、死亡率、残留积累和消耗、抗氧化能力和免疫相关基因表达的影响尼罗罗非鱼被评估。在 24.5–28.5 °C 时，OTC 给药会导致死亡率、采食量减少和生物量减少。第 10 天记录的 OTC 残留量 (161.40 ± 11.10 ng/g) 在食品法典的最大残留限度内。根据欧盟委员会的规定，退出期为 7 天。即使在 OTC 给药后第 42 天，仍存在痕量残留。膳食OTC降低肝脏和肌肉组织的抗氧化能力，并在给药期间显着下调肝脏中肿瘤坏死因子-α、白细胞介素-1β和热休克蛋白-70基因的表达。产生的 OTC 给药生物安全性数据可为制定维护鱼类健康和食品安全的管理策略提供投入。