The physical microhabitat of stream-dwelling fishes is relatively unknown. Work done with albino brook trout suggests the operation of a previously unreported scheme of fish habitation, the focal point concept. This concept is expressed in focal point residency and in movements away from the focal point. Both focal point and movements have quantitative parameters. Each focal point is a relatively small area representing less than 3% of the area over which the fish ranged. During a 50 day study period, an average of 15% of each study section was utilized 95% of the time. Most focal points had a slow water area (0.33 ft./sec. average) overlain by a swift water mass (0.86 ft./sec. average). Study fish occupied the slow water area almost exclusively with the exception of occasional, short (time) trips into the swifter layer. All focal points show a high spatial correlation with cover. A high percentage of time (94%) was spent in shaded areas. Movements are characterized by the occupation of small amounts of time (6% of all observational time) and relatively large areas of the stream (up to 25% of the available stream area). A large percentage of the movements (66%) go away from and directly back to a focal point. Results from a number of one-way analysis of variance computations indicate important relationships between overlying physical factors and the microhabitat chosen by study fishes.