Energy is not a nutrient, and insufficient or excessive energy will affect the growth of tilapia. When designing the formula of tilapia, the balance between energy and protein in feed must be considered. When the energy in the feed is insufficient, protein in the feed will be consumed as energy; However, when the energy in the feed is too high, the food intake of tilapia decreases, and the intake of protein or other important nutrients decreases, thus affecting the growth of tilapia. In addition, the cost of energy is relatively high. ?

2. What is the demand of tilapia for protein?

Protein is a necessary nutrient for maintaining fish life and activities, and its content determines the cost of feed. It is generally believed that the content of protein in feed for tilapia fry and fingerling stage should be 25%-35%, and not less than 25% in adult stage. ?

3. What is the amino acid requirement of tilapia?

The demand of tilapia for protein is essentially the demand for amino acids, especially the demand for essential amino acids. Kanazawa (1987) used isotope C 14 to find that tilapia, like other fish, also needs ten essential amino acids. The experiment of Yang Qingsong et al. (1987) showed that tilapia obtained the best weight gain effect when the amino acid composition ratio of protein in feed was consistent with that of tilapia fish protein. ?

4. What are the requirements of tilapia for fat and essential fatty acids?

Fat in feed is the source of energy and essential fatty acids, which can promote the absorption of fat-soluble vitamins, so it plays an important role in feed formula. Huang Zhongzhi's research shows that tilapia needs higher fat than herbivorous fish, which is 3.6% for grass carp and 6.2% for tilapia. Sato et al. (198 1) think that tilapia needs about 10% fat. It is generally believed that the fat content of tilapia feed should be 4%-6%. ?

5. What is the carbohydrate requirement of tilapia?

Carbohydrate is a cheap energy source in feed. If carbohydrates can be reasonably and fully utilized, the feed cost can be greatly reduced. It should be pointed out that the utilization of carbohydrates by aquatic animals is far less than that of terrestrial animals, and too much carbohydrates in feed will lead to liver injury and fatty liver in aquatic animals. It is generally believed that the suitable carbohydrate content in tilapia feed is 30%-50%. ?

6. What is the vitamin requirement of tilapia?

Vitamin is an essential nutrient for maintaining fish health, promoting growth and regulating physiological functions. Vitamins cannot be synthesized in tilapia and must be obtained from feed. Long-term vitamin deficiency in feed will lead to metabolic disorder of tilapia, and vitamin deficiency will occur in severe cases. Therefore, vitamins must be added to feed. ?

7. What is the mineral requirement of tilapia?

Minerals are essential substances to maintain fish life, including macro elements and trace elements. Because fish can absorb some mineral elements from water, many formulators ignore the importance of minerals. In recent years, due to the lack of inorganic salts, the growth of tilapia is slow, even lacking, which repeatedly shows that minerals still need to be added to tilapia feed.