Fish, high digestibility Purina feeds, such as Aquamax, and Pro Plan for dogs, are indeed 98% digestible and converted into flesh. In the case of Tilapia, Aquamax will create 1 pound of flesh for each 1.2 pounds of feed consumed. This is repeated and documented. The extra loss is due to calories expended. In the wild (pond) an Large mouth bass will consume about 10 pounds of food for each pound gained. Using Aquamax, LMB growth will be about 1 pound flesh to 4 pounds feed, again, with metabolic calories consuming the extra nutrition.
Not all feeds are the same, but the feeds Purina has for high growth are using highly digestible ingredients.
Some low-quality feeds use chicken feathers to "factually" claim a high protein content, yet animals cannot utilize that protein.
