This research project is to obtain data on fish diversity from streams of the southeastern U.S. in order to test predictions of local and regional historical hypotheses of diversity. Four week-long field trips across the southeast are planned over a 12-month period from June 1989 to May 1990. A standard protocol will be followed to sample fishes and collect habitat data from localities selected on the basis of stream size, accessibility, and proximity to U.S. Geological Survey flow-gauging stations. The fish and habitat data will be subjected to correlation analyses designed to test the dependency of local fish diversity on (1) habitat complexity, (2) environmental disturbance, and (3) regional fish diversity.