Technical Abstract: The efficient use of feed for growth and meat production is important for all animal production industries including aquaculture. Residual feed intake (RFI) is an alternative measure of feed efficiency that has been widely used in livestock production. RFI was calculated as the difference between intake observed and intake predicted on the basis of a bioenergetics model; a low RFI indicates greater efficiency. RFI offers some advantages as a selection criterion for improving production efficiency over traditional feed efficiency statistics because it is not a ratio, and it typically has a larger coefficient of variation. The RFI of individually reared rainbow trout progeny from six different genetic cross-types was examined for genetic variation. Proximate analysis and nitrogen retention were also evaluated to determine if differences in RFI correlate to differences in body composition and nutrient retention and varied by cross-type. Differences between cross-types indicated a genetic component for RFI, with the most efficient fish of approximately 160g consuming 0.99g less and inefficient fish consuming 0.05g more feed per day than expected. Lower RFI was associated with higher growth rates (r=-0.38, P<0.05) and greater nitrogen retention (r=-0.82 P<0.001).