Examination of the intestinal contents of 130 striped bass (Morone suxattlis) collected from the Hudson River and Long Island Sound during May to October 1981 showed that opportunistic fish pathogens-especially Aeromonas hydrophtla-predominated in samples from both locations. Other isolates from both groups of striped bass included Vibrio, pseudomonads, flavobacteria, Alcaligenes, and enterics. Small numbers of Micrococcus, Bucillus, Corynebacterium, and Acinetobacter were also isolated. Total numbers of bacteria in the intestines were 100 to 1,O00 times higher in striped bass from the Hudson River than in those from Long Island Sound.