Prepared (artificial) Diets
Prepared or artificial diets may be either complete or supplemental.
Complete diets supply all the ingredients (protein,
carbohydrates, fats, vitamins, and minerals) necessary
for the optimal growth and health of the fish. Most fish
farmers use complete diets, those containing all the
required protein (18-50%), lipid (10-25%), carbohydrate
(15-20%), ash (< 8.5%), phosphorus (< 1.5%), water (<
10%), and trace amounts of vitamins, and minerals. When
fish are reared in high density indoor systems or confined
in cages and cannot forage freely on natural feeds, they
must be provided a complete diet.
In contrast, supplemental (incomplete, partial) diets are
intended only to help support the natural food (insects,
algae, small fish) normally available to fish in ponds or
outdoor raceways. Supplemental diets do not contain a full
complement of vitamins or minerals, but are used to help
fortify the naturally available diet with extra protein, carbohydrate
and/or lipid.
Fish, especially when reared in high densities, require a
high-quality, nutritionally complete, balanced diet to grow
rapidly and remain healthy.