The result of showed that the total phenol content of the ethyl acetate extract of Sargassum was 127.5 mg GAE/g extract, while the total flavonoid content was 107.66 mg QE/g extract. The ethanol extract showed the highest antioxidant activity, with an IC50 of 29.84 ppm.

Meanwhile, in the observation of fish blood test, the use of extract Sargassum in diets with doses 5, 10 and 15 g/Kg during 21 days gave an impact on the number of erythrocytes and percentage of lymphocytes. The highest value of erythrocytes was found in treatment with dose 15 g/Kg on 21st day, 16.57 ± 1.43 x 105 cells/mm3. In case of differential leucocytes test, there was not indicated the influence of the Sargassum extract in diets to the percentage of neutrophils and monocytes of the blood fish. It can be concluded that 15 g/Kg additional extract of Sargassum in diets, which contains the bioactive compound, give the effectiveness of the optimal response immune system in catfish.