Protein Content Experiments
Of course, fish need food too!  You'll find that the more protein you include in the diet of these fish, the faster they will grow.  This may allow you to make higher profits.  As many low-carb/high-protein human dieters have discovered, protein helps keep you lean, but it doesn't necessarily keep you healthy.  As a result, a fish farmer will want to find a feed mixture with optimum protein content.  Protein content is measured in percentage (%), from 0 to 100.  Since fish need some nutrients that are not found in protein-only feed, you will want to try a range that tops out below 100%, probably closer to 65%.  You'll always want to include some protein, probably not less than 10%.  Working with that initial range, you might see some reasonable profits, but you will need to decide what part of the range to focus on more narrowly in order to find an optimum value.