Nutrient Requirements in Fish

Aquatic farming, especially fish farming, has increased dramatically in the last few decades. The aquaculture industry is the fastest growing food production industry in the world. From this sector people get about 50% of the fish production. Significant progress has been made in fish nutrition in recent years. A balanced commercial diet has been developed for the moderate growth and health of fish by studying the nutritional status of fish. The components of a balanced diet are protein, carbohydrates, vitamins, lipids, mineral salts and water. Therefore, for proper growth and proper health of fish, 18-50% protein, 10-25% lipids, 15-20% carbohydrates, <8.5% ash, <1.5% phosphorus, <10% water and a small amount in the supplementary diet ‍are essential.

The presence of vitamins and minerals is essential. When fish are farmed in a high concentration in a culture system, a nutritious whole diet should be used. Satisfactory production of fish cannot be expected without nutritious food. The plankton that is produced in the pond by natural rules is not at all sufficient to meet the overall nutritional needs of the fish. In addition, the shortage of fish food remains irreplaceable in the fertilizers applied to the natural food in the pond. As a result, the fish does not grow. In addition to natural foods, supplements play a significant role in increasing fish production. In case of commercial fish farming, the natural food of the reservoir cannot provide the required nutrients to the fish and shrimp. So in order to get more production, it is necessary to ensure a balanced supply of food for fish.

The nutritional needs of a fish depend on the growth rate of the fish, the nature of the food, the environment of the reservoir, the variation in temperature, and so on. Dissolved nutrients are not present in water in sufficient quantity for rapid physical growth of the organism. Therefore, in order to increase the production, it is necessary to provide additional balanced food to eliminate the malnutrition of the farmed fish. The basic elements of a balanced diet play an important role in intensive and semi-intensive farming for the growth of fish and the activation of various physiological functions of the body.

Plankton as a natural food for fish farming in ponds, the abundance of subterranean organisms such as benthos provide the basic nutrients for fish. However, in order to get higher yields, the basic dietary ingredients such as proteins, carbohydrates, lipids, vitamins and minerals can be easily added to the diet to meet the fish needs.

Nutrients of Fish

Nutrients of Fish is divided into two main types  such as (a) Macro nutrients and (b) Micro nutrients                       

image of Fish nutrients types

Fish Nutrient Types

Macronutrients

The macronutrients are those nutrients that provide calories or energy. Such nutrients are essential for metabolism and other bodily functions. Greek macro means large, so macronutrients are used in large quantities. There are 3 main nutrients namely Protein, carbohydrates and lipids. Among the macronutrients, carbohydrates produce 4 calories per gram, protein 4 calories and fat 4 calories per gram.

In addition to carbohydrates, proteins and fats, there are other elements that provide energy. Such as alcohol. Alcohol produces 8 calories per gram of energy. Alcohol is not called a macronutrient because it is not needed for survival. There is a role for body maintenance and taste and food intake which makes food more characteristic and enjoyable.

Micronutrients

Micronutrients are those nutrients that are needed in small amounts. Although the main nutrients play an important role, not only are they sufficient to survive, but micronutrients are also required. Micronutrients or secondary nutrients are vitamins and minerals.

Protein

The word protein comes from the Greek word β€˜proteios’ which means first. It is an important biological molecule (biomolecule) that is made up of smaller units called amino acids. The amino acids are connected to each other by peptide chains and the chains are joined by sulfhydrol bonds, hydrogen bonds with energy.

The chemical composition of proteins varies greatly from the compounds of any biologically active group. Protein consists of 50% carbon, 16% nitrogen, 21.5% oxygen and 8.5% hydrogen. Proteins vary in size or shape. Some polypeptides carry only 20-30 amino acids, others carry a few thousand amino acids. In every living cell, skin, hair, bonemarrow, muscles, tendons and ligaments contain proteins.

Proteins combine with each other to form body structures and participate in defense. Enzymes, hormones, antibodies and globulins affect, control and protect the body's chemical reactions. Important organic molecules such as hemoglobin, myogenesis and various lipoproteins carry oxygen and other elements in the body and provide energy to the body.

Protein is a complex molecule. It breaks down when the body needs it. That is why they are the slowest and longest source of energy from carbohydrates. During digestion, proteases break down proteins under the influence of enzymes to produce amino acids. Some absorbed amino acids are converted into carbohydrates through glucogenesis. When hungry, the organism can produce and use glucose from its own body proteins. This condition is especially seen in muscles.

Lipid

Lipids are high energy nutrients used in fish farming as a partial alternative to protein. It provides almost twice as much energy as protein and carbohydrates. It is an important component of the diet because it is rich in fat-soluble vitamins and essential fatty acids. Along with lipid, proteins act as important components of the cell membrane and mitochondria. It is a naturally occurring organic compound commonly known as oil and fat. It manages cell structure, energy storage and various biological functions.

Carbohydrates

Carbohydrates are a large organic group that contains glucose, starch and cellulose. Its common feature is that it contains only carbon, hydrogen, and oxygen, and their combustion produces carbon dioxide and one or more molecules of water.

The simplest carbohydrates are the three carbons that play an important role in metabolism at the secondary level. Polysaccharides are more complex carbohydrates that exist naturally. It is primarily plant-based components. Two types of polysaccharides are very important in the diet of animals and fish.

(A) Structural Polysaccharides: These carbohydrates can be digested by herbivorous fish species. The polysaccharides included in this class are cellulose, lignin, dextran, manganese, inulin, pectic acid, algic acid, agar and chitin.

(B) Universally Digestible Polysaccharides: This type of polysaccharide is mainly starch. 3/4 of the plant is made up of such carbohydrates. However, glycogen, sugars and a small amount of carbohydrates are present in animals. Glycogen is called animal starch because it is not found in plants. Monosaccharide constituents such as carbohydrates, amino sugars and D-oxy sugars are the constituent elements of all organisms.

Minerals

Minerals are a type of basic substance. Mineral elements are the inorganic elements that are required for the management and maintenance of important physiological processes in the organism such as Calcium, Phosphorus, Sodium, Sulfur etc. Minerals act as organic catalysts for enzymes, hormones and protein in the body. About 23 types of inorganic minerals perform the necessary functions in the organism. Of these, 6 are the minerals that the body needs in moderation and such minerals are referred to as macro-elements. On the other hand, 18 minerals are required in very small amounts in the body of the organism, such minerals are called micro-elements or Trace Minerals. Secondary elements, along with other minerals, play a major role in the nutrition and production of fish.

Supplemental food and water serve as a source of fish minerals. Fish can take these elements as ions with the help of gills and skin. Rui fish (Labeo rohita) get essential minerals from plankton and pond bottom animals and decomposed organic matter. In the absence of such elements, just as the growth of fish is reduced or diseases are caused by pests, their high presence also hinders the growth rate of fish. Fish not only absorb such inorganic nutrients through food but also from the external aquatic environment. Inorganic elements are inextricably linked with the way fish live.

Table: Nutrient Requirements in Carnivorous Fishes

Nutrients

Fish Size


Fry

Fingerling

Grower

Broodstock

Crude Protein (%)

45-50

40-45

35-40

40-45

Amino acids(%)





Arginine

2.24

2.11

1.94

2.02

Histidine

0.96

0.89

0.82

0.85

Isoleucine

1.46

1.37

1.26

1.32

Leucine

2.66

2.50

2.30

2.40

Lysine

3.08

2.90

2.66

2.78

Methionine1

1.36

1.28

1.18

1.23

Phenylalaline2

2.71

2.55

2.35

2.46

Threonine

1.67

1.58

1.45

1.51

Tryptophan

0.31

0.29

0.27

0.28

Valine

1.73

1.63

1.50

1.56

Crude Lipid(%)

14-16

12-14

10-12

8-10

Fish oi l:  plants oil

7 : 1

7 : 1

7 : 1

7 : 1

Carbohydrate(%)

15

20

25

25

Crude Fibre(%)

1.0

1.5

2.5

2.5

Minerals





Calcium(%)

2.50

2.50

2.00

2.00

Phosphorous(%)

1.00

0.80

0.70

0.80

Vitamin Primix(%)

0.5-1.0

0.5-1.0

0.5-1.0

0.5-1.0

Source: NRC (1993); Jauncey(1998); Lovel(1998); Ali(2001); Ali and Jauncey(2003). 1Total methionine+Cystine; 2Total phenylalaline+tyrosine

Table: Nutrient Requirements in Omnivorous Fishes

Nutrients

Fish Size


Fry

Fingerling

Grower

Broodstock

Crude Protein (%)

40-45

35-40

30-35

30-35

Amino acids(%)





Arginine

1.81

1.68

1.51

1.59

Histidine

0.76

0.71

0.64

0.67

Isoleucine

1.18

1.09

0.98

1.04

Leucine

2.15

1.99

1.97

1.89

Lysine

2.48

2.31

2.07

2.19

Methionine1

1.10

1.02

0.91

0.97

Phenylalaline2

2.19

2.03

1.83

1.92

Threonine

1.35

1.26

1.13

1.19

Tryptophan

0.25

0.23

0.21

0.22

Valine

1.40

1.30

1.16

1.23

Crude Lipid(%)

8-10

7-10

6-8

5-7

Fish oi l:  plants oil

1 : 1

1 : 1

1 : 1

1 : 1

Carbohydrate(%)

30.00

35.00

40.00

40.00

Crude Fibre(%)

1.50

2.00

4.00

4.00

Minerals





Calcium(%)

2.50

2.50

2.00

2.00

Phosphorous(%)

1.00

0.80

0.70

0.80

Vitamin Primix(%)

0.5-1.0

0.5-1.0

0.5-1.0

0.5-1.0

Source: Mazid et al.(01979); NRC (1993); Jauncey(1998); Lovel(1998); Hossain and Fruichi(2000);  Ali(2001); Ali and Jauncey(2003). 1Total methionine+Cystine; 2Total phenylalaline+tyrosine

Table: Nutrient Requirements in Prawn/shrimps

Nutrients

Prawn/shrimp  Size


PL

 (1-2.5 mg)

PL

 2.5 mg-1.0 g)

Juvenile

Grower

Broodstock

Crude Protein (%)

40-45

40-45

35-40

30-35

35-40

Amino acids(%)






Arginine

2.71

2.44

2.17

1.90

2.44

Histidine

0.77

0.69

0.62

0.54

0.69

Isoleucine

1.19

1.07

0.95

0.83

1.07

Leucine

2.45

2.20

1.96

1.71

2.20

Lysine

2.57

2.31

2.06

2.80

2.31

Methionine1

1.42

1.27

1.14

0.99

1.27

Phenylalaline2

2.72

2.44

2.17

1.90

2.44

Threonine

1.68

1.51

1.34

1.18

1.51

Tryptophan

0.47

0.42

0.38

0.33

0.42

Valine

1.49

1.34

1.19

1.04

1.34

Crude Lipid(%)

11-13

10-12

9-11

8-10

10-12

Fish oi l:  plants oil

5 : 1

5 : 1

5 : 1

5 : 1

5 : 1

Carbohydrate(%)

20.00

25.00

30.00

35.00

25.00

Crude Fibre(%)

1.50

2.00

2.00

3.00

2.00

Minerals






Calcium(%)

3.00

2.50

2.50

2.00

2.50

Phosphorous(%)

1.60

1.40

1.20

1.20

1.40

Vitamin Primix(%)

0.5-1.0

0.5-1.0

0.5-1.0

0.5-1.0

0.5-1.0

Cholesterol(%)

1.50

1.50

1.00

1.00

1.50

Source: Mazid et al.(01979); NRC (1993); Jauncey(1998); Lovel(1998); Hossain and Fruichi(2000);  Ali(2001); Ali and Jauncey(2003).  1Total methionine+Cystine; 2Total phenylalaline+tyrosine

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