Bdellovibrio and like organisms (BALOs) are predatory bacteria and have potential for biocontrol of pathogenic bacteria. In order to provide scientific reference for study, application and market supervision of the BALOs preparations, this study was to evaluate the quality of commercial BALOs preparations used for aquaculture. Using double layer agar technique, the plaques contents of BALOs preparations manufactured by eight companies was counted with different bacteria as preys, and the prey range of plaque isolates were tested. The preparations and the plaque isolates were also identified by PCR with three pairs of taxonspecific primers targeting various BALOs groups. The 16S rRNA genes of two representative Bdellovibrionaceae isolates were sequenced and compared with that of related sequences, and the phylogenetic tree of Bdellovibrionaceae was constructed based on genetic distance analysis. The results showed that most of the BALOs preparations being examined were not qualified, only two of the eight preparations gained positive amplification by Bdellovibrionaceae primers, and showed visible plaques on the double layer agar. One of the two Bdellovibrionaceae positive preparations, JSF, had two kinds of plaque isolates with different morphologies and prey patterns, and significant differences were found when counted with different preys. About 1.4 kb 16S rRNA genes were sequenced and deposited in the GenBank with accession numbers EU884925 and EU884926 for the two kinds of plaque isolates, JSF1 and JSF2, respectively. Based on the phylogenetic analysis of 16S rRNA gene sequences, JSF1 and JSF2 were offiliated with cluster 1 (B. bacteriovorus) and cluster 5 (the species undefined) respectively in Bdellovibrionaceae. However, the plaque isolates of the other preparation contained no BALOs.