Aeromonas is a Gram-negative, facultative anaerobic, rod-shaped bacterium that morphologically resembles members of the family Enterobacteriaceae. Most of the 14 described species have been associated with human diseases. The most important pathogens are A. hydrophila, A. caviae, and A. veronii biovar sobria. The organisms are ubiquitous in fresh and brackish water. [1]
They group with the gamma subclass of the Proteobacteria