Ten experimental diets and one control diet were fed to 720 tilapia (20 fish × 12 cages × three replicates) in a recirculating aquaculture system to determine the economic significance of replacing fishmeal with fishmeal analogs if the fishmeal analogs were processed on-site by the producer. All experimental diets were produced at Illinois State University using an Insta-Pro Model 600 Jr. extruder plus grinding, weighing and mixing equipment commonly found on commercial livestock operations. Primary diet protein sources included corn gluten meal, corn gluten feed and distillers dried grains. All diets were balanced for amino acid requirements of the fish, and both 32 and 36% crude protein diets were fed. There was no significant difference in feed conversion ratio (FCR) between diets with fishmeal and diets without fishmeal. There was no significant difference in FCR between 32 and 36% crude protein diets. An economic engineering model which included all equipment necessary for extruding and handling pelleted feed on-site was developed. Annualized investment and operating costs were estimated to determine the total cost of processing each of the 10 experimental diets. There was a significant difference in cost of gain among the 10 experimental diets and the control diet. Cost of production was highly sensitive to volume of feed extruded.