infects a number of cultured fish species, causing heavy economic loss in Guangdong province. We evaluated the prevalence of infection with in tilapia ( ( ( using a standard microbiological assay and specific PCR. Using PCR, we detected in all three species (30.21%, 23.53%, and 14.55% of individuals, respectively). However, was only isolated from using the traditional microbiological assay. was detected in all tissues, includingmuscle were more susceptible to than the other tissues in tilapia (infection rate: 20.65%bass (infection rate: 12.1% , respectively). There was no difference in the susceptibility of the tissues in . Moreover, our results suggested that body length was inversely correlated with the infection rate by