Two 16S rRNA gene-based PCR primer sets (Brod541F/Amx820R and A438f/A684r) for detecting anammox bacteria were compared using sediments from Mai Po wetlands (MP), the South China Sea (SCS), a freshwater reservoir (R2), and sludge granules from a wastewater treatment plant (A2). By comparing their ability in profiling anammox bacteria, the recovered diversity, community structure, and abundance of anammox bacteria among all these diverse samples indicated that A438f/A684r performed better than Brod541F/Amx820R in retrieving anammox bacteria from these different environmental samples. Five Scalindua subclusters (zhenghei-I, SCS-I, SCS-III, arabica, and brodae) dominated in SCS whereas two Scalindua subclusters (zhenghei-II and wagneri) and one cluster of Kuenenia dominated in MP. R2 showed a higher diversity of anammox bacteria with two new retrieved clusters (R2-New-1 and R2-New-2), which deserves further detailed study. The dominance of Brocadia in sample A2 was supported by both of the primer sets used. Results collectively indicate strongly niche-specific community structures of anammox bacteria in different environments, and A438f/A684r is highly recommended for screening anammox bacteria from various environments when dealing with a collection of samples with diverse physiochemical characteristics.