Hatchery-reared Atlantic salmon (Salmo salar), wild Atlantic salmon and brook trout (Salvelinus fontinalis) (O+ year-class fish) were observed in allopatric or paired sympatric populations using stream tanks at the Matamek Research Station, Quebec. Hatchery-reared salmon maintained a position just off the substrate, a position intermediate to that occupied by wild salmon (bottom) and trout (midwater). Growth rates of hatchery-reared and wild salmon were not statistically different. Neither type had an interactive advantage. It is concluded that the behavioral pattern of hatchery-reared salmon was intermediate to that of wild salmon and trout. This behavioral shift may account for poor survival of planted Atlantic salmon juveniles, a phenomenon suggesting the need for a reexamination of present live release programs using juvenile hatchery-reared salmon.