Brachionus plicatilis is the most common rotifer species that has been cultured for fish farming. However, all applicable studies of B. plicatilis have been concerned about its nutritional values in aquaculture; while there is little attempt to use it as a potential source for medical bioactive substances. Therefore, the study aimed to culture the rotifer B. plicatilis in sustainability with Cyclotella sp. (as feeds), to applying its extractions as antitumor, antimicrobial, and antioxidant. B. plicatilis crude had a significant impact on the cell growth inhibition of MCF-7 cells (breast cancer), where the maximum cell growth inhibition (91.53 %) was detected with 10 mg/ml of the extract. On the other hand, the Gram-positive organisms (Staphylococcus aureus, Streptococcus mutans and Methicillin-Resistant Staphylococcus aureus) were moderately sensitive for the B. plicatilis extract, and their inhibition zones (16, 13 and 11 mm, respectively) were smaller than that (24, 20, and 15 mm, respectively) produced by gentamycin (control). Otherwise, the activity of B. plicatilis extracts against Gram-negative organisms was zero except with Salmonella typhimurium, which produced a very small inhibition zone (8mm). Also, the rotifer B. plicatilis extract showed antioxidant activity, but their IC₅₀ value was larger than IC₅₀ that belongs to ascorbic acid, which means that the antioxidant ability of ascorbic acid is stronger than B. plicatilis crud extract sample. Therefore, B. plicatilis crud extract may have a promising future in the treatments of many diseases, including cancer, and bacterial infection.