Types of fish feed：
1.pellet feed
The diameter of fish pellet feed is usually 2.5-8.0 mm and the length is 5-10 mm, which can be directly sprinkled and fed. If the feed is damp, do not feed it directly. It should be dried or sun-dried first, and then fed; if the feed deteriorates, it should not be fed again to prevent fish poisoning after eating.
2.cake feed
Cake feed should be crushed, soaked, and refined for small fish, and then macerated for medium to large fish.
3.grain feed
Large-grained grains such as corn should be processed and crushed before being fed to fish; small grains such as grains can be germinated and fed to fish. The young and tender grain white buds have high nutritional value, and fish are easy to digest, absorb quickly, and gain weight quick.
4.green fodder
For medium to large fish, the green feed can be directly fed after removing the soil; for small fish, it should be chopped or beaten, and then mixed with 0.2% salt, and then sprinkled and fed. Chop the green feed and cook it, add some bran and soda, the small fish prefer to eat it.
5.Bran feed
When feeding small fish, the dregs and bran feed should be soaked and refined; when feeding medium to large fish, it should be fermented until it smells like wine. Feed a small amount at the beginning of feeding, and gradually increase the amount later, but it should not exceed 30% of the total daily feeding.
6.protein feed
Earthworms, fly maggots, insects, etc. are all high-quality animal protein feeds for fish, which can be fed directly, or dried and processed into powder, and then combined with other feeds to feed fish. For lump animal feed, it should be chopped and finely ground, and then added with binder to form small balls for feeding.
Selection of feed ingredients：
The selection of raw materials should be based on the principle of high quality and low price, stable supply and convenient transportation. When conditions permit, the more types of raw materials, the better, so that the essential amino acids in the feed can be balanced as much as possible, and the needs of fish for various essential amino acids can be satisfied to the greatest extent. Moldy and deteriorating raw materials must not be used. Moldy and deteriorating raw materials contain a large number of germs and toxins. For example, moldy corn contains highly toxic aflatoxin. These feeds can easily cause fish diseases after feeding.
Although raw materials such as cottonseed meal and rapeseed meal are cheap and have high protein content, they contain anti-nutritional factors such as gossypol and glucosinolate respectively, excessive use will affect the growth of fish, so the amount should be limited , generally no more than 10%.
Many farmers like to use cheap oil residue and meat cakes, but such raw materials are mixed with a lot of animal fur, which affects the smooth progress of the crushing and granulation process, and fish are not easy to digest after eating. The fat contained in oil residue and meat pie is saturated fat, and the utilization rate of saturated fat by fish is low. Excessive intake of rancid fat will also cause fish to suffer from fatty liver and other diseases, so the amount of such raw materials should be Control it below 5%. In addition, when selecting raw materials, attention should also be paid to the moisture content of the raw materials. Excessive moisture will reduce the nutritional value of the feed, and may also lead to mildew of the feed and shorten the storage time of the feed.
Rational design of feed formula:
Before designing the formula, the species and growth stages of the fish must be clarified in order to determine the level of nutrients such as protein and energy in the feed. It is necessary to meet the protein needs of fish growth, but also to make the ratio of energy and protein moderate. Too high or too low energy protein ratio is not conducive to fish growth. When designing the formula, the relationship between feed nutrition level and bulk density should also be considered, so as to ensure that fish can take in sufficient nutrition and make them feel full. Fish mainly use protein as an energy source, and the utilization rate of fat and sugar is low, so the demand for protein is higher than that of livestock and poultry. Different stages of fish growth have different requirements for various nutrients. For example, the protein content in feed for juvenile carp is 41% to 43%, that of fingerlings is 37% to 42%, and that of adult fish is 28% to 32%.
