There are fish species in the Chattahoochee River that do not occur in tributaries. For example, trout inhabit the Chattahoochee River where they find the cool water necessary for their survival. This cool water originates as deep-water releases from Buford Dam at Lake Lanier north of Atlanta. The water temperatures of tributaries in Metropolitan Atlanta are too warm to support trout. The group with the largest number of species is the minnow family.
Minnows are small fish that can be seen darting around in streams that are only a few feet wide.
Other families with large numbers of species are the sunfish and bass family, the catfish family, and the sucker family. Species that have the largest numbers of individuals living in streams typically are minnows and suckers. These species are often not well known because unlike sunfish, bass, and catfish, people do not fish for them, although certain minnows may be used as bait. Minnows have an important role in the aquatic food chain as prey for larger fish, aquatic snakes, turtles, and wading birds such as herons. Although suckers are not popular game fish, they are ecologically important because they often account for the largest fish biomass in streams.