CATDOLL : CATDOLL: How to raise fish fry?

1. Feeding the newly hatched fry, which is 0.2-0.3 cm long, lives by absorbing nutrients from the yolk sac in the body. 2-3 days after hatching, the nutrients in the yolk sac are absorbed and transported away, the fish's digestive system has initially developed and the swim bladder is filled with gas, and the fry begin to swim in all directions to find food. For these newly started fry, rotifers and ciliates should be fed with appropriate amounts of zooplankton, i.e. "water return". If there is no "water return", you can feed cooked egg yolks. The method is to wrap the egg yolk with 1-2 layers of gauze, squeeze it, and then place the gauze bag on the water surface and pat it gently, moving it while patting, so that the egg yolk is evenly suspended in the water for the fish to eat. Feed twice a day, and the feeding amount should be eaten within 1 hour. After 7-10 days of feeding in this way, the fry will gradually grow larger, and you can stop feeding egg yolks and feed live water fleas instead. When the fry grows to more than 1 cm, you can feed various types of rotifers.

2. Change the water After the fry are hatched, the leftover food accumulates in the water. If it rots over time, it will affect the life of the fry, so the water needs to be changed. The water should be changed by dehydration, that is, when changing the water, pour the fish and the relatively clear old water into the new water. The first dehydration is carried out about 10 days to half a month after hatching, and then every half a month. After three dehydration, the fry has reached a total length of about 2 cm, and the water should be changed. Because the resistance of fish is weak, the temperature difference of water change should be kept within 4℃.

3. Fish selection and pond division During the growth of fry, the best and the worst should be continuously selected according to the characteristics of various farmed fish to ensure the cultivation of excellent Kushiliang varieties. Generally, one broodstock for breeding needs about 4 to 5 selections before it can meet the requirements. The selection standards and methods are as follows: The first selection of fish, after 10 days to half a month of incubation, when the fry is about 1.5 cm long, you can start selecting, mainly eliminating those with single tails, deformed tails and irregular tail handles. After the selection of fish, the remaining good fish are stocked in ponds at a density of about 150 per square meter. The second selection of fish, when the fry grows to more than 2 cm, the tail fin has been formed. All fish that do not have 3 or 4 tails will be eliminated. The third selection of fish, eliminate fish with incomplete dorsal fins. The remaining good fish are stocked in ponds at a density of about 120 per square meter. The fourth and fifth selections of fish, when the fry have grown into young fish, can be combined with the characteristics of the variety, mainly based on morphology. For example, in dragon eyes, the left and right eyeballs should be the same size; the bubbles in blister eyes should be large and symmetrical on both sides, and so on.

Introduction to Practical Grass Carp Breeding Technology

1. Living habits

1. Food habits

Grass carp is a typical herbivorous fish. In the natural state, adult fish mainly eat aquatic plants. The species they like to eat include Vallisneria, Hydrilla verticillata, duckweed, etc. Under artificial breeding conditions, they are fed with various aquatic plants, terrestrial grasses and various concentrated feeds. In the early stage of fry cultivation, the young fish eat small protozoa such as rotifers, and in the summer flowering stage, they eat large zooplankton such as cladocerans and then transform to eating duckweed, sedge and tender aquatic and terrestrial grasses. They like to eat artificial concentrated feeds at all growth index stages. 2. Growth

Grass carp is a large economic fish that grows fast. It grows fastest at 2-3 years old. Under pond conditions, the group growth rate of 1-year-old fish is generally 50-60g, 2-year-old fish can reach 500-750g, and 3-year-old fish can reach 2-3kg, so the grass carp breeding cycle is 2.5-3 years. Sexual maturity is 4-5 years old, and the growth rate slows down significantly after 5 years old. Male and female individuals have similar growth rates from 1 to 3 years old. After 4 years old, females grow faster than males. 3. Reproduction

Grass carp is a fish of large rivers. Under natural conditions, there are spawning grounds in the main main rivers of my country. Parent fish can swim to the spawning grounds to lay eggs and reproduce during the spawning season, but this is not possible under artificial pond conditions.

The sexual maturity age and individual size of grass carp are closely related to latitude (heat). In southern my country, sexual maturity age is 3-4 years old and weight is about 14kg; in central China, sexual maturity age is 4-5 years old and weight is about 5kg; in northeast China, sexual maturity age is 6-7 years old and weight is about 6kg. In addition, sexual maturity is also related to nutritional conditions. Different nutrition will result in different sexual maturity age and weight. Males are generally one year earlier than females and are smaller than females. 2. Artificial breeding 1. Broodstock selection

Selecting qualified broodstock with good germplasm and physique is one of the basic conditions for artificial breeding of grass carp. The so-called good germplasm means that according to the investigation and research on the germplasm of the "Four Major Carps" in my country's "Three Rivers" (Yangtze River, Pearl River, Heilongjiang River), the germplasm of the Yangtze River is the best, so it is ideal to choose the original grass carp of the Yangtze River. The so-called good physique means that the fish is strong, with normal body color, complete scales, and no injuries or diseases. Individuals that have not reached sexual maturity are used as reserve broodstock, and mature individuals are used as broodstock for production that year. When selecting broodstock, attention should also be paid to the matching of males and females. Generally, there are slightly more males than females. 2. Broodstock breeding

(1) Broodstock rearing pond. The area of ​​the broodstock rearing pond is 2/15-4/15hm2 (2-4 mu), and the water depth is 1.5-2.5m. It is located near the spawning pond, with convenient drainage and a quiet environment. Use quicklime to clean the pond before stocking.

(2) Stocking density. About 2,250 kg of broodstock are stocked per hectare of pond. The male-female ratio is 1:1 or 1:1.25. In order to make full use of bait and regulate water quality, on the premise of mainly raising grass carp broodstock, 50-60 silver carp or bighead carp broodstock can also be mixed per hectare.

(3) Feed. The feed for broodstock mainly consists of artificially planted grasses and terrestrial grasses such as ryegrass, Sudan grass, and elephant grass, as well as aquatic Vallisneria and Hydrilla verticillata. Other feeds include various cereals and artificial compound feeds.

(1) Time and water temperature for inducing labor: In the middle and lower reaches of the Yangtze River, the time for inducing labor is mid-to-late May, and the most suitable water temperature is 25-28 degrees.

(2) Selection of broodstock: The maturity of broodstock directly affects the effect of induced spawning. The identification criteria are that when the abdomen of the male fish is gently squeezed, semen flows out and immediately disperses when it comes into contact with water. The abdomen of the female fish is swollen, soft and elastic, and the scales on the abdomen are sparse. In order to improve the maturity of the group, a net can be pulled in mid-April for inspection. For those with poor maturity, LRH-A3~5 micrograms/tail can be injected according to individual size and maturity. 4. Estrus and artificial insemination

There is chlorine in the water, which causes the seedlings to die.

The water for stocking must be treated with water stabilizer before it can be used to raise fish. If there is no water stabilizer, you can only turn on the oxygen pump to assist. At this time, do not add salt. Adding salt will cause the fish's protective film to fall off, reduce the resistance of the fry, the water surface will be filled with bubbles, and the dissolved oxygen content in the water will decrease, which is not conducive to the survival of the fry.

I agree with the above statement. There are chemical components in tap water, such as chlorine and some heavy metals. Fish feel oppressed. Another reason is that the oxygen content is too low. The fish density is too high, which leads to low oxygen content.

There are some cheap fish treasures on the market. Put them in and it will be fine. Add some coarse salt to sterilize and disinfect. Putting an air pump will make things better.

Best wishes.