I believe we've found what this fish is. It appears to be a spotted bullhead. The largest recorded appears to be 9 inches.
Here is some documentation we found on it:
spotted bullhead
It is mainly found in the Apalochicola, Ochlockonee, and Suwannee river systems in Florida, Alabama and Georgia. It is classified as Rare in Florida and Georgia, and of Special Concern in Alabama.
It is usually found in larger streams and rivers with moderate current, and shows a preference for rock bottoms. Snails have been found to be the dominant food type by volume, and another common name for this fish is "snail cat".