Cooperative Fish and Wildlife Research Units Program: South Dakota
Education, Research and Technical Assistance for Managing Our Natural Resources

Carnivorous fish species, like rainbow trout, Oncorhynchus mykiss, require high levels of dietary protein. Historically, fish meal has been the primary protein source, but supply can be variable and relatively expensive. Alternative protein sources are needed to meet the dietary protein demand for ever-increasing aquaculture production. In addition to specific dietary requirements, salmonids may react positively to exercise during hatchery rearing, with increased growth and feed conversion. While fishmeal alternatives have received considerable research focus, no studies have examined the use of plant-based diets in conjunction with exercise. In this study, we examined the replacement of fishmeal with fermented soybean meal product in salmonid diets during typical hatchery rearing practices, and evaluated the utility of this alternative protein source in the diets of salmonids subjected to rigorous exercise during hatchery rearing. Based on the results of these experiments, bioprocessed soybean meal can replace 100% of the fishmeal in diets of Brown Trout during normal rearing, and at least 60% of the fishmeal during continual exercise. Bioprocessed soybean meal can replace at least 80% of Rainbow Trout diets, regardless of the exercise regimen.