Creel returns of stocked rainbow trout Oncorhynchus mykiss are often below management objectives. In the Hoover Dam tailwater, Colorado River, predation by striped bass Morone saxatilis limits creel returns of stocked rainbow trout. On two occasions, we stocked large (33‐em) and small (21–25‐cm) rainbow trout into the tailwater to compare returns to the creel. Angler return rates for the two stockings were 47% and 22% for the large fish and 1 % and 2% for the small fish. Costs of large fish returned to the creel were US$6.02 and $12.86 per fish for the two stockings. Costs of small fish returned to the creel were $59.00 and $29.50 per fish for the two stockings. Annual survival of large rainbow trout did not increase compared with small fish. Stocking large rainbow trout is a cost‐effective option for the Hoover Dam tailwater and may improve creel returns in other waters where predation limits survival of stocked fish.