The growth of global aquaculture has put intense pressure on sources of fish oil and fishmeal for aquafeeds. GM soybeans could provide substitutes in high Omega-3 soybean oil (STA oil), as well as soy protein concentrate (SPC). This paper examines the technological and economic feasibility of substituting STA oil for one-half the fish oil in the diet of S. rivoliana. We find that the two feed technologies are essentially identical, with respect to growth pattern, feed consumption, and flesh quality. Economic feasibility depends upon the price of STA oil being lower than the price of fish oil. We estimate that it will be when it becomes available. The estimated production cost savings is small (about 1%). However, the potential global market for STA oil could be as much as 250 thousand metric tons annually; which would require soybean production equivalent to that from 1.6% of current U.S. soybean area.