1. Plant feed: Of course, the most ideal feed in koi fish is animal feed. However, in the absence of animal feed for various reasons, plant feed can be used as emergency or life-sustaining auxiliary feed. Weeds and aquatic plants are common, among which weeds are one of the smallest species of seed plants. Plants are as small as sand and have no roots, so they are more nutritious. The other is duckweed, which has filamentous roots. Koi fish eats when he is hungry. Generally, he can only feed the older koi fish, not more. Before feeding, carefully check whether there are pests and eggs, or soak in low-concentration potassium permanganate solution for a while before feeding, otherwise it is easy to bring in germs and pests.

2. Animal feed: Animal feed is one of the most popular and nutritious feeds for fish in koi fish.

① Fish worms: Fish worms, commonly known as red worms and water fleas, are zooplankton that breed in sewage pits, ponds and rivers, commonly known as various water fleas.

② Cyclops: Cyclops are blue-gray and belong to copepods in crustaceans. Its advantages are strong vitality, fast swimming speed and being able to live for several days. However, its disadvantage is its small size. If it is used to feed old parents, it will be more difficult to hunt because of its fast swimming speed, and Cyclops can also bite their young. Therefore, it is best to scald it with boiling water when feeding cyclops.

③ paramecium: paramecium, commonly known as grey water, is a general term for several protozoa in plankton. It can be cultivated with straw, which is most suitable for feeding newly hatched fry.

(4) Dragonfly: the south is called blood worm, and the north is called oil jump. They are chironomid larvae, and their body color is red, so they are named blood worms. They are nutritious, expensive, difficult to preserve and need to be refrigerated. So ordinary couples can just freeze it and feed it.

⑤ Water earthworm: There are many kinds of water earthworm, which is koi fish's favorite. It is rich in protein, fat and vitamins. Generally living on the surface of sewage sludge in fertile rivers or flowing water, one end pierces the sludge and the other end swings with the water. It is small, soft, bright red or crimson and easy to be swallowed by koi fish, but it must be washed repeatedly before feeding. If you can, you must keep it for a few days.

3. Synthetic feed: It is not enough to catch natural bait fish and worms to develop the scale of koi fish's aquaculture. In addition to the artificial breeding of fish and insects, it is also necessary to develop the production of compound pellet feed and supply it to the market, which can not only solve the feed source of farms, but also meet the needs of koi fish fans for family rearing and frolicking in koi fish. With artificial feed, it is much more convenient to raise koi fish at home. The compound pellet feed has comprehensive nutrition and meets the needs of growth and development in koi fish. The main ingredients should include sugar, fat, inorganic salts and vitamins.

① protein: protein is the main component of koi fish's body. Its function in the body is to grow new tissues and repair old tissues, and it is also a component of heating. There must be enough protein in the bait to promote the rapid growth of koi fish.

② Sugar: Sugar is the main substance of heat energy in koi fish and the main feed component in koi fish.

③ Fat: Fat is the food with the highest thermal energy storage. Its physiological function is the same as sugar, and it is oxidized in the body to supply energy. Generally speaking, the lack of fat in feed, slow growth and small size of koi fish will reduce the tolerance of fish to low temperature and hypoxia, which will easily lead to overwintering death. Too much fat and overweight fish will hinder the development of gonads.

4 inorganic salts: inorganic salts are the main elements that constitute the color skeleton, such as calcium phosphate and calcium carbonate. Fish blood and muscle leaves also contain a certain amount of calcium and phosphorus. A certain amount of calcium in feed can promote digestion and help absorb fat and phosphorus. Koi fish can not only get calcium and phosphorus from feed, but also permeate calcium and phosphorus from water through skin and gills. Koi fish also needs trace elements such as iron, copper, magnesium, sodium, potassium and diamonds. Without these elements, it will grow slowly and cause diseases. In order to ensure the normal growth of koi fish, feed should contain these elements.

⑤ Vitamins: Vitamins are also necessary for the growth of koi fish. Long-term lack of vitamins, fish body dysplasia, slow growth or complete stop, or even deformity, the resistance to adverse external environment and various fish diseases decreased. Lack of vitamin A will lead to fin cracking, fish pigment disappearance and pale body color. Lack of vitamin E will make gonads underdeveloped or underdeveloped, and at the same time reduce the resistance to aquatic fungi. Adding a small amount of vitamin B 12 to feed can promote growth.