Curcumin Supplementation Mitigates Oxytetracycline-Induced Hematological, Immunological, and Oxidative Stress in Rainbow Trout (Oncorhynchus mykiss)

Abstract

Simple Summary Oxytetracycline is an antibiotic commonly used to treat bacterial diseases in farmed fish, but its use may also cause unwanted effects on fish health. Curcumin, a natural compound obtained from turmeric, has antioxidant and immune-supporting properties and may help reduce these adverse effects. This study investigated whether adding curcumin to the diet could protect rainbow trout against physiological disturbances caused by oxytetracycline. Fish were fed diets containing different levels of curcumin for eight weeks and were subsequently exposed to different concentrations of oxytetracycline. Oxytetracycline adversely affected blood characteristics, immune responses, and the balance between oxidative damage and antioxidant defenses. Dietary curcumin generally reduced these changes, and higher dietary levels tended to provide greater protection, although the degree of improvement varied among the parameters and tissues examined. The highest tested curcumin level generally produced the most favorable overall response. These findings suggest that dietary curcumin may be a useful natural feed additive for supporting fish health during antibiotic-associated stress. Further studies are needed to determine its long-term effectiveness, safety, and practical application under commercial aquaculture conditions.