The objective of the research is to characterize the diversity of Aeromonas and verify the presence of ecotypes in an urban river of Northeast of Brazil along a salinity gradiente. 140 cultivable strains with morphological characteristics similar to Aeromonas species were isolated. Of the total, 59 strains (42%) were confirmed by biochemical tests, of which 28 were identified by gentotypic similarity to species and the remainder classified as Aeromonas spp, among them: A. hydrophila, A. cavie, A. veronii and A. media. According to the results obtained, the phenotypic identification key used in this work was very efficient for the identification of the genus Aeromonas, since it confirmed all the isolates tested as Aeromonas. Analysis of similarity among the isolated Aeromonas strains showed the presence of 29 Aeromonas ecotypes. However, the large number of ecotypes found suggests that the environment, over time, has caused substantial genotypic changes in the strains of the genus Aeromonas