Nitrogen accumulation is a serious concern in aquaculture. Among otherforms of nitrogen nitrite is more harmful because of its low transformation rate and high toxicity. In this study, 27 strains, which can reduce nitrate to nitrite, were isolated from a shrimp pond by using selective enrichment cultures under alternating oxic-anoxic denitrifying conditions. Among these strains, 24 strains effectively decreased nitrate and nitrite concentrations during a 7-day test. The strains LZX21, LZX22, LZX23, LZX27 deceased nitrate concentrations from 422.25mg/L to lower than 4.00mg/L, and deceased nitrite concentrations to lower than 0.40mg/L. Sequence analysis of 16S rDNA indicated that the 27 strains belonged to five separate groups of α-proteobacteria (1), γ-proteobacteria (10), Actinobacteria (12), Firmicutes (3), and bacteroides (1). Moreover, these strains were classified into or showed close relationship to 11 genera including Pseudomonas, Halomonas, Acinetobacter, Paracoccus, Arthrobacter, Microbacterium, Cellulosimicrobium, Bacillus, Stenotrophom, and Sphingobacterium. These data suggest that a high diversity of bacteria capable of removing nitrate/nitrite was present in the shrimp pond. Several species were reported for the first time to have capability of nitrate/nitrite removal. These strains provide a plentiful resource for further selecting nitrite cleaners.