2.2. Analytical methods
Initial and final proximate composition of diets and fish carcass were analyzed for
protein, lipid, fiber, ash, and moisture following methods of AOAC (1984). Defatted whole body fish carcass and bone samples were analyzed for calcium and phosphorus
content. Vertebrae bone was separated from adhering tissue by subjecting to pulsed
microwave in a Philips Cooktronic M718 microwave oven. Calcium was determined by
a dry ash method with potassium permanganate titration (AOAC, 1984). Phosphorus
was determined by a mixed acid digestion followed by addition of molybdovanadate
(Yoshida et al., 1976).