We constructed energetic models of habitat use for 82ยฑ322 g rainbow trout (Oncorhynchus mykiss) in a large regulated river, and 8ยฑ28 g Colorado River cutthroat trout (O. clarki pleuriticus) in a small headwater stream, to determine if observed summer habitat use by these species could be attributed to net energy acquisition, and to develop habitat suitability criteria based on net energy gain. Metabolic models of energy expenditure were derived from literature sources, but measurements of energy availability were site-speciยฎc. From the energy models, we assigned a suitability value of 1.0 to the entire range of velocities where positive net energy gains were predicted, and a suitability value of zero to velocities where negative net energy gains were predicted. Predicted net energy gain velocities were compared with observed velocities used by each species. For rainbow trout, the energetic model predicted energetically proยฎtable velocities ranging from 5 to 45 cm s ร1 . Predicted velocities were similar to velocities used by rainbow trout. This indicated that rainbow trout, as a group, were using energetically proยฎtable stream locations, but some rainbow trout used non-proยฎtable velocities. For Colorado River cutthroat trout, the energetic model predicted energetically proยฎtable velocities ranging from 5 to 45 cm s ร1 ; however, Colorado River cutthroat trout used signiยฎcantly lower velocities than predicted. The dissimilarity between velocities predicted and used by Colorado River cutthroat trout may be attributed to their inability to utilize energetically proยฎtable velocities available in the stream because of depth restrictions. The results suggest that the predictive abilities of energetic models vary between streams because of differences in depth and velocity availability.