In the central Columbia River, southeastern Washington, bridgelip suckers (Catostomus columbianus) were common in deep water with strong currents during daylight and moved into slower shallow water at night. Mean calculated fork lengths (FL) in millimeters at annulus formation were age I, 63; II, 148; III, 224; IV, 291; V, 335; VI, 36I; VII, 387; VIII, 401; IX, 408. Back-calculated lengths approximated lengths at capture for respective ages. The length-weight (W) relationship for both sexes was logeW = - 12.65 + 3.25 logeFL. Both sexes reached maturity at about 350 mm FL and age VI. Peak spawning in all years occurred during May in water temperatures of 8–13 C. Breeding males and females both exhibited a narrow red lateral line stripe. Estimated egg numbers per mature female ranged frown 9,955 to 21,040. Bridgelip sucker diet was almost entirely periphyton, except fish smaller than 150 mm FL utilized mainly aquatic insect larvae and zooplankton. Variability of taxonomic characters caused some difficulty in distinguishing bridgelip suckers from sympatric largescale suckers (C. macrocheilus).