What Do Koi Fish Eat? Koi Food Selection and Feeding Guide
The carp originated in Central and Western Asia, later spread to China, and from China was introduced to other countries. It is gentle by nature, likes to swim in groups, is easy to keep, and has strong adaptability to water temperature. Moreover, koi are omnivorous fish with fairly undemanding food requirements, making them very suitable for hobbyists to keep. Let's take a look below at what koi fish eat!
Koi's Living Habits
Koi are suited to living in slightly alkaline water with low hardness. Like goldfish, they are not demanding about water temperature or water quality, and they adapt strongly to the environment. The most suitable water temperature is 20-25°C; within this temperature range, koi have a robust appetite, swim actively, and are strong in constitution with vivid colors. They can also survive within a water temperature range of 2-30°C, but they cannot tolerate sudden changes in water temperature. Under long-term artificial rearing conditions, koi can still endure a temperature difference of 2-3°C, but once this range is exceeded, it very easily triggers abnormal behavior and certain diseases in koi. For example, when the temperature difference is 7-8°C, the koi will lie at the bottom of the water without eating or moving, and if the temperature difference continues to suddenly increase, then all you can do is quietly wait for the koi to suddenly die.
What Do Koi Fish Eat
Koi are omnivorous fish. Generally speaking, mollusks, benthic animals, fragments of higher aquatic plants, and even tiny algae can all serve as koi food, and they can also dig out some food from the pond bottom mud. As the fish grows and the seasons change, their feeding situation also changes accordingly. In summer, koi feed most intensively, while in winter they hardly eat at all. For newly hatched fry, the food is basically mainly rotifers and small cladocerans; for juvenile fish over 3 cm, the food is benthic organisms, insect larvae, ostracods, river snails, and fragments of higher aquatic plants.
Koi have a very broad range of adaptability to fish food, and their requirements for living conditions are not very strict either, so they have strong vitality. Of course, artificially formulated fish food is now also the primary choice for feeding koi, and its nutritional composition is also very rich, making koi healthy, beautiful, and energetic.
Types of Koi Food
1. Plant-based feed: Of course, animal-based feed is the most ideal feed for koi, but when animal-based feed is lacking for various reasons, plant-based feed can serve as an emergency or life-sustaining supplementary feed. Common ones include duckweed and aquatic plants, among which duckweed is one of the smallest types of seed plants. The plant body has no roots or stems, is tiny like sand, and its nutritional composition is also fairly good. Another is small duckweed, which has a thin thread-like root. Koi will also eat it when hungry; generally it can only be fed to larger koi, but it should not be fed too much. Before feeding, carefully check for pests and insect eggs, or soak it briefly in a low-concentration potassium permanganate solution before feeding, otherwise it can easily introduce pathogens and pests.
2. Animal-based feed: Animal-based feed is one of the feeds that koi love most and that is richest in nutrition.
① Water fleas: Water fleas are commonly known as bloodworms, Daphnia, etc. They are zooplankton that breed in sewage pits, ponds, and rivers, and are the common name for various species of Daphnia.
② Cyclops: Cyclops are blue-gray in body and belong to the copepods among crustaceans. Their advantages are strong vitality and fast swimming, and they can be kept alive for several days without dying, but their disadvantage is their small body size. If used to feed old broodstock several years old, because they swim fast, they are even harder to catch and eat. Moreover, cyclops can also bite small fry, so when feeding cyclops, it is best to scald them with boiling water first.
③ Paramecium: Paramecium is commonly known as gray water, and is the common name for several protozoans among plankton. It can be cultured with rice straw, and is most suitable for feeding newly hatched fry.
④ Mosquito larvae: Called bloodworms in the south and "youbeng" in the north, these are the larvae of chironomid midges. Their body color is blood-red, hence the name bloodworm. They are rich in nutrition and relatively expensive, and are not easy to preserve, requiring refrigeration. Most hobbyists simply freeze them and then feed them.
⑤ Tubifex worms: There are many species of tubifex worms. Tubifex worms are what koi love most to eat, and they contain abundant protein, fat, and vitamins. They generally live in the surface layer of the sludge of fertile rivers or flowing ditches, with one end inserted into the sludge and the other end swaying with the water. They are small, soft, and bright red or dark red in body, and are easily swallowed by koi. However, before feeding, they must be rinsed repeatedly, and if conditions permit, they must be kept for a few days until the tubifex worms have spit out the mud before feeding.
3. Formulated feed: To develop koi farming on a large scale, relying only on catching natural bait such as water fleas cannot meet the demand. In addition to carrying out artificial culture of water fleas, the production of compound pellet feed must also be developed to supply the market. On one hand, this can solve the feed source problem for farms, and on the other hand, it can also meet the needs of koi hobbyists keeping koi at home. With artificial feed, keeping koi at home is much more convenient. Compound pellet feed is required to have a complete nutritional composition that meets the needs of koi growth and development. Its main components should include 5 major categories: protein, carbohydrates, fat, inorganic salts, and vitamins.
① Protein: Protein is the main component of the koi's body. Its role in the body is to grow new tissues, repair old tissues, and it is also a component of heat energy supply. The bait must contain enough protein to promote rapid growth of koi.
② Carbohydrates: Carbohydrates are the main substance of heat energy in the koi's body, and are the main feed component for koi.
③ Fat: Fat is the food that stores the highest heat energy. Its physiological function is the same as that of carbohydrates, supplying energy through oxidation in the body. Generally speaking, if the feed lacks fat, koi grow slowly and are small in size, and the fish body's endurance to low temperature and hypoxia will be reduced, easily causing death during overwintering. If there is too much fat, the fish body becomes too fat, which will hinder the development of the gonads.
④ Inorganic salts: Inorganic salts are the main elements that make up bones, such as calcium phosphate and calcium carbonate. Fish blood and muscle also contain a certain amount of calcium and phosphorus. A certain amount of calcium in the feed can also promote digestion and help the absorption of fat and phosphorus. In addition to obtaining calcium and phosphorus from feed, koi can also permeate calcium and phosphorus from water into the body through the skin and gills. Koi also need trace elements such as iron, copper, magnesium, sodium, potassium, and cobalt. Lack of these elements will cause slow growth and disease. To ensure the normal growth of koi, the feed should contain these elements.
⑤ Vitamins: Vitamins are also essential for koi growth. Long-term vitamin deficiency leads to poor development of the fish body, slow growth or complete cessation of growth, and may even produce deformities, with reduced resistance to adverse external environments and various fish diseases. Lack of vitamin A can cause splitting of the fish fins, disappearance of body pigments, and fading of body color so that it is not vivid. Lack of vitamin E will cause poor gonadal development or no development, and at the same time greatly reduce resistance to aquatic fungi. Adding a small amount of vitamin B12 to the feed can promote growth.