Raising rainbow trout to larger “steelhead” harvest sizes (e.g., 3-4 kg) is a niche production approach in the U.S. trout industry, where a much smaller harvest size has traditionally been the norm. Additionally, there is growing interest in land-based recirculating aquaculture system (RAS) production of steelhead trout, i.e., trout produced in a similar manner to the growing land-based Atlantic salmon RAS industry. To inform land-based RAS production of steelhead, baseline research is necessary, including the assessment of various commercially-available strains in an effort to identify the best performing strains in the novel RAS environment. To this end, we evaluated six separate groups of steelhead trout from three domestic sources: i) USDA-ARS growth & fillet yield-selected strain; ii) Producer #1, who provided both all-female diploid and triploid strains; and iii) Producer #2, who provided all-female diploids and two separate groups of triploids. All fish were initially received as eyed eggs from their respective sources, cultured and raised in flow-through tanks until approximately 150 g in weight, and then stocked into a semi-commercial scale RAS and raised to a target harvest size of 4 kg. Additionally, all strains received either constant photoperiod or a winter signal photoperiod (i.e., 6 weeks of 12h light, 12h dark, followed by a return to constant photoperiod) to induce smoltification, to determine whether this process might confer additional performance benefits during growout. A portion of each group was PIT-tagged, with repeated data collection on tagged individuals throughout the growout trial. Final data collection at 4 kg prior to harvest included length, weight, condition factor, coefficient of variation, gonadosomatic indices, deformities, fin condition, fillet yield, fillet color, and fillet proximate composition and fatty acid profiles. At the time of abstract submission, the steelhead strain assessment trial has just been completed, and data are currently being analyzed. Final analyses and recommendations will be presented at Aquaculture America 2023.