Suzhou Creek is an urban river across Shanghai City and its adjacent areas. In the present study the river environmental quality was assessed based on fish communities. The specimens sampled in the year 2001 were compared with those collected in Shanghai Science and Technology Museum (formerly Shanghai Museum of Natural History) in the 1960s. The number of species decreased from 62 in the 1960s to 44 in 2001, with the most prominent decrease in the species of Gobioninae that are benthos and insectivores. Marked change was also seen in trophic dominance. Percentage of species as piscivores decreased from 27.4% in the 1960s to 22.7% in 2001, and insectivores from 24.2% in the 1960s to 11.4% in 2001. On the other hand, the percentage of species as omnivores increased from 25.8% in the 1960s to 38.6% in 2001 and turned to be prominent dominance. The diversity of species in the upper stream is higher than that in the downstream. Such changes indicate that the food web was simplified and the biological integrity was decreased. It is inferred that the creek substrate degrading has caused the changes in the habitats of the aquatic creatures in Suzhou Creek.