Technical Abstract: For the predicted continual growth of aquaculture to continue it will be necessary to develop diets with protein and oil from sustainable sources. In North America there are a number of crops that possess desirable qualities for either protein or oil replacement in aquaculture feeds. In Idaho, a significant producer of rainbow trout, barley and oats are being studied for protein replacement. Cultivars of these cereal grains enhanced for high levels of protein and oil and reduced in phytic acid have been incorporated into trout feeds and studied for their effects in the diet and the fish. To date over 45 different cultivars have been examined demonstrating slight to dramatic changes in effects depending upon the characteristic differences between the cultivars. Findings indicate that fish utilize the protein from these grains quite well, but in order to increase the protein replacement potential of these grains in aquaculture diets will require cultivars with greatly augmented protein levels or improved methods for the isolation and concentration of protein from these grains. To further augment our research, studies have begun using molecular assays to determine how slight changes in diets affect the growth and health of the animals on the feed. This presentation will present our cumulative findings to present.