Farm A, found the most have infected with Steptococcus spp as 77.7%. As well Farm c and d have infected with s.iniae as 11.11% by the prevalence of nile tilapia have infected with s.agalactiae and s.iniae as 33.33% which s.agalactiae all as 14.81% and the prevalence of all S. iniae infection as 18.51%.The sampling nile tilapia in cages at Tapi river. Nakhon si Thammarat. During the period November 2556 - February 2557 from a comparison of MSD Animal health authorities have found that the prevalence of S.agalactiae is equal to 82% and the prevalence of S. iniae is equal to 18%.