This study aimed to analyze the cold stress effects (in terms of hematology, energy reserves, and oxidative stress) in Piaractus mesopotamicus (pacú) and their mitigation by a Pyropia columbina red seaweed-supplemented diet. For this purpose, juvenile fish were fed with a control (CD) or a red seaweed-supplemented diet (RD) for 60 days, and then, the animals were exposed to a low temperature (14 °C) and a control temperature (24 °C) for 24 h. The cold shock generated an increase of hemoglobin levels in fish fed with both diets. In CD-fed fish, plasmatic triglycerides, cholesterol, and hepatic glycogen decreased after the thermal shock; meanwhile, the animals fed with RD showed decreased hepatic proteins, but increased cholesterol and hepatic glycogen. Regarding oxidative stress, antioxidant enzymes augmented their activity in the liver, intestine, and gills; meanwhile, lipid oxidative damage was observed in the liver and intestine of fish exposed to 14 °C and fed with both diets. Pacú was sensitive to cold shock, but no mitigation effects were observed in fish fed with the supplemented diet. Further research should target higher concentrations of P. columbina in supplemented diets to take advantage of this valuable resource.

本研究旨在分析美索不达米亚梭鱼(Pacú)的冷应激效应（在血液学、能量储备和氧化应激方面）及其通过Pyropia columbina 的缓解红海藻补充饮食。为此，给幼鱼喂食对照 (CD) 或红海藻补充饲料 (RD) 60 天，然后将动物暴露在低温 (14 °C) 和控制温度 (24 °C) 24 小时。冷休克导致用两种饮食喂养的鱼的血红蛋白水平增加。在 CD 喂养的鱼中，热休克后血浆甘油三酯、胆固醇和肝糖原下降；同时，喂食 RD 的动物表现出肝脏蛋白质减少，但胆固醇和肝糖原增加。关于氧化应激，抗氧化酶增强了它们在肝脏、肠道和鳃中的活性；同时，在暴露于 14 °C 并喂食两种饮食的鱼的肝脏和肠道中观察到脂质氧化损伤。帕库对冷休克很敏感，但在用补充饲料喂养的鱼中没有观察到缓解作用。进一步的研究应该针对更高浓度的P. columbina在补充饮食中利用这一宝贵资源。