Giant clam marine culture is commonly influenced by a wide variety of pathogenic bacteria including Vibrio species, resulting in high losses. The current study was organized to investigate the bacterial infections, in the Hurghada area, between the culture of Tridacna maxima and Tridacna gigas in indoor aquaria and offshore cages. Eighty samples of T. maxima and T. gigas in both indoor aquaria and offshore cages were collected for bacteriological analysis. Samples were taken from gills, gut, mantels, and gonads of Tridacna. The results showed reduced motion followed by loss of attractive color pattern with 25 % and 20 % mortality rate among indoor cultured T. maxima and T. gigas, respectively. About forty-six bacterial isolates were identified, using phenotypic and biochemical testing.  Most of those isolates were Vibrio logei, V. harveyi, and unidentified Vibrio. The pathogenicity and virulence of V. logei seem high with a 30% mortality rate. The current study would provide useful information for better management of bacterial infections in T. maxima and T. gigas.