Photoperiod and temperature often change concomitantly in nature and regulate physiological responses that ultimately determine the health of species. However, the impact of these changes is poorly investigated from the perspective of optimal conditions for the management of fish, and the association of these variables. In this study, we evaluated the levels of oxidative stress, antioxidant response and the numbers of leukocytes in specimens of Colossoma macropomum submitted to the combination of three photoperiods (0L:24D, 12L:12D, and 18L:6D) and three temperatures (26, 29 and 32 °C) during 60 days. Our main findings showed an increase in oxidative damage of up to 141% and an antioxidant response of up to 167% in animals under 18L:6D – 32 °C. The results showed an interaction between photoperiod and temperature on immunity, with an increase in the number of lymphocytes (37%), monocytes (60%) and eosinophils (226%) between 26 and 32 °C. Thrombocytopenia (−96%) occurred with the rise in temperatures and thrombocytosis (139%) occurred with a simultaneous decrease in photoperiod and a temperature of 26 °C. A reduction in neutrophils was observed in animals exposed to 18L:6D – 32 °C in relation to the group 12L:12D – 32 °C (−67%). The data suggested that, due to increased oxidative damage, the farming of tambaqui in an extended photoperiod under high temperatures makes the animal more susceptible to inflammation and alters its ability to deal with infections. In addition, variations in the profile of thrombocytes suggested that the increase in the photoperiod at lower temperatures requires physiological adjustments to support changes in the farming conditions.

光周期和温度通常在自然界中随之变化，并调节最终决定物种健康的生理反应。但是，从鱼类管理的最佳条件以及这些变量的关联的角度出发，对这些变化的影响的研究很少。在这项研究中，我们评估了巨像的标本中氧化应激，抗氧化反应的水平和白细胞的数量在60天内经受了三个光周期（0L：24D，12L：12D和18L：6D）和三个温度（26、29和32°C）的共同作用。我们的主要发现表明，在18L：6D – 32°C下的动物中，氧化损伤最多可增加141％，抗氧化反应最多可增加167％。结果显示，光周期和温度之间存在相互作用，在26至32°C之间，淋巴细胞（37％），单核细胞（60％）和嗜酸性粒细胞（226％）数量增加。血小板减少症（−96％）随着温度升高而发生，而血小板减少症（139％）随着光周期和26°C的温度同时降低而发生。相对于组12L：12D – 32°C（−67％），在暴露于18L：6D – 32°C的动物中嗜中性粒细胞减少。数据表明，由于氧化损伤增加，在高温下在延长的光周期内养殖坦巴基，使该动物更容易发炎，并改变了其应对感染的能力。另外，血小板分布的变化表明在较低温度下光周期的增加需要生理调节以支持耕作条件的变化。