Vibrio species are associated with numerous outbreaks of diseases in marine fishes. In such instances, Vibrio anguillarum, Vibrio alginolyticus, or Vibrio parahaemolyticus have been isolated from diseased species, In pond-cultivated brown shrimp (Penaeus aztecus) coryneform bacteria and Vibrio predominated. Although mortalities among brown shrimp caused by V. parahaemolyticus have been observed in laboratory aquaria, there is at present no firm indication that this organism is a major problem in pond-cultivated shrimp in-Texas.