Abstract. The study was conducted in three black tiger shrimp (Penaeus monodon Fabricius, 1798) ponds and three whiteleg shrimp (Litopenaeus vannamei Boone, 1931) ponds in the Bac Lieu province, Vietnam. The results showed that the environmental parameters in shrimp ponds, such as temperature, pH, salinity, total ammonia nitrogen (TAN), nitrate (NO3 - ), phosphate (PO4 3- ), total nitrogen (TN), total phosphorus (TP), and chlorophyll-a, were relatively high and suitable for the growth of shrimp. A total of seven and six species of Rotifera were recorded in black tiger shrimp and whiteleg shrimp ponds, respectively. The Rotifera species number varied from 6-7 species (27-31%) in shrimp ponds. The Brachionus plicatilis species had the highest frequency (100%) during the sampling periods. Rotifera abundance tended to decrease considerably after 1-7 days of shrimp stocking. The mean density of Rotifera in whiteleg shrimp ponds tended to be higher than that in black tiger shrimp ponds. The development of Rotifera was significantly affected by TN concentrations (p0.05) with levels of temperature, pH, salinity, TAN, PO4 3- , TP, and chlorophyll-a in the brackish shrimp ponds. The Rotifera composition included Brachionus angularis, Brachionus plicatilis, Hexarthra mira, Philodina sp., Synchaeta sp., Ploesoma sp., Synchaeta sp1., Trichocerca sp., and Colurella adriatica. Key Words: abundance, Brachionus plicatilis, natural food.