en aquaculture aquaculture پژوهشي Orginal research papers Because of the importance of rotifers as an adequate live food in larviculture, this study was conducted to evaluate probiotic potency of four microorganisms, <em>Candida parapsilosis</em>, <em>Pseudoalteromonas flavipulchra</em>, <em>Lactobacillus sakei</em> and <em>Bacillus natto</em> on suppression of <em>Vibrio</em> species and increasing population growth, enzymes activity and nutrients retention in the rotifer, <em>Brachionus plicatilis</em>. Four experimental and a control treatment, each with four replicates, with the concentration of 10⁸CFU/mL^-1 for each strain were applied. The results demonstrated that <em>L. sakei</em> and <em>B. natto</em> successfully suppressed <em>Vibrio</em> in experimental treatments and increased population growth and nutrients retention. The longevity of <em>B. natto</em> was recorded as the best in long-term inoculation than other treatments and the control in a way that after 8 days of rotifers starvation, the count of <em>B. natto</em> increased. The findings showed that the two bacteria, <em>B. natto</em> and <em>L. sakei</em>, appear to be a promising probiotic for rotifers in suppressing <em>Vibrio</em> and also in increasing population growth, nutrients retention, enzymes activity and long-term inoculation in rotifers. Rotifer, Suppression, Vibrio, Enzyme, Brachionus, Probiotic. 3018 3033 http://jifro.ir/browse.php?a_code=A-10-317-2&slc_lang=en&sid=1 J. Sahandi sahandijavad@gmail.com 100319475328460038346 100319475328460038346 No College of Marine Life Science, Ocean University of China, Qingdao, China P. Sorgeloos Patrick.Sorgeloos@ugent.be 100319475328460038347 100319475328460038347 No Lab of Aquaculture and Artemia Reference Center, Ghent University, Ghent, Belgium H. Xiao xiaoh28@163.com 100319475328460038348 100319475328460038348 No College of Marine Life Science, Ocean University of China, Qingdao, China H. Wang xhwang@ouc.ed.cn 100319475328460038349 100319475328460038349 No College of Marine Life Science, Ocean University of China, Qingdao, China Z. Qi zizonqi@ouc.edu.cn 100319475328460038350 100319475328460038350 No College of Marine Life Science, Ocean University of China, Qingdao, China Y. Zheng sahandi_javad@yahoo.com 100319475328460038351 100319475328460038351 No College of Marine Life Science, Ocean University of China, Qingdao, China X. Tang tangxx@ouc.edu.cn 100319475328460038352 100319475328460038352 Yes College of Marine Life Science, Ocean University of China, Qingdao, China