Proteins are the most amazing group of
molecules in the human body. They are
incredibly complex chains of smaller molecules called amino acids. These strings of amino acids are then folded
into complicated shapes to create millions of critical body components. The DNA
double helix is a familiar example of a protein.
The protein requirements for different fish
species range from 28 to 56 percent of dry diets. Apparently marine and
freshwater carnivore’s species require 40 to 55 percent dietary protein, while
most freshwater omnivore’s species require 30 to 40 percent of their dry diet
to be made up of protein. Like finfish, most crustaceans studied to date have
rather high protein requirements, ranging from 30 to 60 percent of the dry
diet. Proteins consist of various amino acids, the composition of which gives
individual proteins their unique characteristics. Many of the biochemical
required for normal bodily functions are proteins, such as enzymes, hormones
and immunoglobulin’s. Fish, like other animals, synthesize body proteins from
amino acids in the diet and from some other sources. Amino acids that must be
provided in the diet are called “essential” or “indispensable” amino acids.
Meeting a fish’s minimum dietary requirement for protein, or a balanced mixture
of amino acids, is critical for adequate growth and health. However, providing
excessive levels of dietary protein is both economically and environmentally
unsound because protein is the most expensive dietary component and excess
protein increases the excretion of nitrogenous waste.
