Fish Nutrient Requirements

NUTRIENT REQUIREMENT OF FISH

The major dietary nutrient requirement of aquaculture species to promote growth and body maintenance are proteins and amino acids, carbohydrates, lipids and fatty acids, minerals and vitamins.

8.2.1 Proteins and amino acids:

Proteins are large complex organic compounds which perform an essential role in the structure and functioning of plants and animals. They comprises of about 70% of the dry weight of fish muscle. Proteins are the polymerized units of amino acids linked with peptide bonds and cross-linked between chains with sulphydryl and hydrogen bonds. The protein requirement of aquaculture species are influenced by various factors such as, water temperature, fish size, feed allowance, protein quality,

Nutritionally, amino acids may be classified as either indispensable (essential) or dispensable (non-essential). An indispensable amino acid is one that the animal cannot synthesize in quantities sufficient for body needs; thus must be supplied in the diet. A dispensable amino acid is one that can be synthesized by the animal in quantities sufficient for maximal growth. The essential amino acids are Arginine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Cystine, Phenylalanine, Tyrosine and Valine.

The major protein sources for aquaculture feed are fish meal, soybean powder, groundnut cake, cotton seed meal, zooplanktons and

They are required in small amounts in the diet for normal growth, health, reproduction and general metabolism. Vitamin requirements in aquatic animals are affected by the size of the animal, growth rate, stage of sexual maturity, diet formulation, disease and environmental conditions. Vitamins are classified into two groups:

1) Water soluble vitamins example: B complex, B and C.

2) Fat soluble vitamins example: A, D, E and K.

Sources of vitamins include; Fish, ensiled yeast and vitamin premix.

8.2.6 Feed Additives:

Feed additives are usually added in small quantities to feed ingredients during feed formulation. They are added to feed: To prevent spoilage, improve digestibility of the feed and aids in the binding property of the feed.

8.3 TYPES OF FEED

8.3.1 Natural food: These are live food produced by nature used in feeding aquatic organisms. Natural live foods are both from plants and animal origin. Many of these organisms are rich in protein and other essential nutrients. Live natural foods include phytoplankton, zooplankton and invertebrates such as crustaceans and insects. Plankton is large microscopic organisms which are suspended in water. They are made up