CATDOLL : CATDOLL: How to raise Koi seedlings

1. How to raise koi seedlings

1. Fish fry cultivation

There are two ways to raise fish fry: small cement pool raising and pond raising.

1. Cement pool cultivation

(1) Cement pool preparation: The size is generally 4m×2m×0.8m or 4m×4m×0.8m, and equipped with oxygenation facilities. The cement pool for cultivating fry should be soaked in 15ppm potassium permanganate solution for about 7 days before the fry are put into the pool. The spawning pool can also be used for on-site cultivation.

The first selection: It is carried out within 20-30 days after the fry are hatched, starting when the fish grows to about 3 cm. The main purpose is to select individuals with strong physique, active swimming and obvious species characteristics, and eliminate other individuals, or cultivate and sell them separately. However, the growth rate and the time when the stripes form are different due to different species. For example: Showa three-color koi starts to be selected about 15 days after hatching, golden koi starts from about 50 days after hatching, and red and white series and Taisho three-color series koi start from about 60 days after hatching.

Second selection: Starts about 20 days after the first selection. The selection criteria are the shape of the fins, the brightness of the colors, the clarity of the patterns, the obvious characteristics of the breed, etc.

The third and fourth selections thereafter were basically the same as the second selection.

(2) Stocking density: 250 to 400 fry per square meter. The fry released into each cement pond should be from the same batch of breeding.

(3) Water quality management: The dissolved oxygen level should be above 4 ppm, and the water should be changed once a day, about 1/3 each time.

(4) Feed: Before the fish reaches 3 cm in length, they are generally fed with plankton such as bloodworms and chlorella, soy milk, etc. After the fish grows to 3 cm, they can be fed with artificial compound feed, generally 3 to 4 times a day.

(5) Pond division: When the fish grow to about 3 cm, the fry need to be selected, which is the time for pond division. After pond division, they enter the commercial fish breeding stage.

(6) Disease prevention and control: The stocking density in cement ponds is relatively high. During the breeding process, it is important to observe the fish's activities, find out the causes of any abnormalities, and treat any diseases promptly.

2. Pond cultivation

(1) Pond preparation: The pond for breeding koi fry is generally 1 to 2 mu in size and 1.5 meters deep, with convenient water inlet and outlet. About 15 days before the fry are released into the pond, 75 to 100 kg of quicklime per mu should be used for pond cleaning and disinfection. Three days later, add 70 cm of new water. When adding water, filter it thoroughly to prevent harmful organisms and wild fish from entering.

After adding water, apply 300~400kg of fertilizer per mu to cultivate palatable bait for the fry after they are released into the pond.

(2) Stocking density: about 100,000 water lilies per acre. Before stocking, test the water and check the toxicity of the water.

(3) Feeding: Feed soybean milk 3 to 4 times a day, about 3 kg of soybeans per mu per day. The weight will increase by 5 kg after 5 days, and the amount will gradually increase as the fish grows.

(4) Feeding and management: As the fish grow, gradually deepen the water level to about 1.2 meters, maintain the water transparency at 30 cm, and remove debris from the pond in a timely manner. When the fry grow to more than 3 cm, divide the pond in time for commercial fish breeding.

2. Breeding of commercial fish

1. Cement pool breeding: The so-called cement pool breeding is to separate the fry cultivated in the cement pool into ponds for breeding and fattening, and then raise commercial fish.

(1) The size of the cement pond is 4m×2m×0.8m or 4m×4m×0.8m. Before stocking the fry, it is soaked in 15ppm potassium permanganate solution for about 7 days and equipped with oxygen supply facilities.

(2) Stocking density: 100 to 150 summer flowers per square meter.

(3) Feeding: Mainly artificial expanded pellet feed, sinking pellet feed and bloodworms, feeding at 3-5% of the fish body weight.

(4) Feeding and management: Change the water in time, once a day, 1/3 of the water each time, and pay attention to the activities of the fish to prevent them from getting sick.

2. Pond breeding:

(1) Pond preparation: The pond should be 3 to 5 mu in size, 1.5 m deep, and have convenient water inlet and outlet. 15 days before stocking the fish, the pond should be cleaned, disinfected, and filled with new water.

(2) Stocking density: Generally, 5,000 to 8,000 summer flower fish are stocked per mu. Usually a single species is raised, but different species can be mixed according to needs.

(3) Feeding: mainly extruded feed or sinking pellet feed, with a crude protein content of more than 28%. Feed once every day at 9-10 am and 3-4 pm. The extruded feed should be eaten up within 10-15 minutes after feeding. The sinking pellet feed is fed by a feeding machine, and the amount is based on 3-5% of the number of fish in the pond, and is adjusted appropriately according to climate changes and fish growth. Appropriately adding additives rich in color-enhancing substances to the bait, such as spirulina, Antarctic krill, alfalfa powder, shrimp skin or artificial pigments, can make the commercial fish bright and colorful and increase sales value.

(4) Feeding and management: Regularly patrol the pond, pay attention to the growth and activity of fish, pay attention to changes in water quality, keep the water fresh, detect and treat fish diseases in a timely manner, and keep the pond clean.

(III) Fish disease prevention and control

Koi likes to swim, is strong and has few diseases, so prevention is the main treatment for koi diseases, supplemented by treatment. Koi diseases mainly include gill rot, enteritis, trichodina, ichthyosis, spore worm disease, etc. The prevention and treatment methods can refer to the prevention and treatment methods of the four major carps.

It depends on how big your fry are, how many there are, and what kind of shape you want to grow them into. Generally, it is very troublesome to raise them at home, because if the fry are too small and the density is too high, the water quality will deteriorate very quickly, which requires powerful filtration assistance. In the fry stage, ordinary pumping methods can easily pump out the fry, especially when feeding, which is generally fed with brine shrimp larvae and egg yolks, but these two things are very detrimental to water, so it is not recommended to raise them at home. If the density is small or there is a large body of water, it is another matter.

0.2% urea plus 0.1% potassium dihydrogen phosphate mixture for watering.

2. How to raise small fish fry

Just water and oxygen

The amount of water does not matter

Any oxygen supply will do.

Can't raise small fish

You can raise big fish

3. How should we raise and care for newly born fish fry?

1. Separate the fish by size and leave the small fish in the original tank. Add appropriate amount of duckweed for the small fish to attach to. Remove the small fish when they can swim parallel to the water and hover in the water.

2. Turn off the oxygen pump and water pump for 10 days, then turn on the oxygen pump in a very small amount, enough to allow small fish to escape.

3. No feeding is required for the first two days, and egg yolks are fed on the third day. Put the cooked egg yolks into a small cup, add a small amount of water, knead it into a paste, and then add water to make egg yolk water. Use a water gun for children to spray the egg yolk water in a mist form. The amount should not be too much.

Additional information:

Things to note when overwintering fry:

1. Increase dissolved oxygen. Hypoxia in water is also a major cause of death of pond fish during winter. It is necessary to keep the number of phytoplankton and dissolved oxygen in the water of the wintering pond relatively stable, increase the light in the water layer, control phytoplankton, prevent excessive organic matter, and increase dissolved oxygen.

2. Prevention of low temperature. Low temperature in winter pond water is a major cause of large-scale fish deaths during the winter. Because farmed fish cannot survive in water temperatures below 0.5°C for a long time, and fish introduced from warm areas and raised at high densities are even less tolerant to low temperatures, so in the winter management of fish, we must control and reduce the occurrence of low temperatures as much as possible, especially to prevent mechanical stirring of water from causing a sharp drop in water temperature, and do not let the bottom water temperature drop below 2°C.