Selenium (Se) is an essential trace element for salmon, acting as a key component of antioxidant enzyme (glutathione oxidase, GPx), supporting immune function, growth and stress resistance. GPx acts along with Vitamin E to function as a biological antioxidant to protect polyunsaturated phospholipids in cellular and subcellular membranes from peroxidative damage. The function of GPx is complementary to that of Vitamin E, which is a lipid soluble antioxidant. Se also enhances T-cell proliferation and antibody production to reduce susceptibility to bacterial and viral infections.
Se levels in fish meal are generally high. However, due to the increase replacement of fish meal with plant ingredients, it may be necessary to supplement Se to meet the physiological requirement of salmon fish. A dietary deficiency of Se has been generally reported to resulted in muscle degeneration and increased mortality under stress.
Interestingly, the toxicity of Se was established well before its dietary essentiality. Therefore, U.S. FDA allows Se supplementation of up to 0.3 ppm from sodium selenite or sodium selenate. In salmon fish, supplemented yeast derived Se appears to have a higher bioavailability and tissue accumulation. Therefore, European Food Safety Authority limited supplemental yeast derived Se to 0.2 ppm.
Salmon feed pellets can be formulated with selenium to help support antioxidant defence, immunity, growth and stress resilience in modern aquaculture diets.
It is noticed that the dominant forms of Se in fish meal and plant ingredients are seleno-methionine and seleno-cysteine. Commercial organic forms of Se include seleno-methionine and yeast derived Se. In extrusion processing, yeast derived Se is more thermal stable. Redox is now providing 3000 ppm and 2000 ppm yeast derived Se containing seleno-methionine 55% and 75%, respectively.
In summary, selenium plays a vital role in supporting salmon health, particularly through its antioxidant, immune and stress-protection functions. As aquaculture diets continue to shift away from fish meal toward plant-based ingredients, targeted selenium supplementation becomes increasingly important to maintain optimal performance and reduce the risk of deficiency-related health issues.
Given the narrow margin between selenium requirement and toxicity, selecting a safe, stable and bioavailable source is critical. Yeast-derived selenium offers a practical solution in salmon nutrition, combining strong bioavailability with thermal stability during feed processing, making it a valuable option for modern feed formulations.
A study compiled by our Redox Animal Nutritionists.