CATDOLL : CATDOLL: Is the survival rate of 2-liang mandarin fish fry high?

Is the survival rate of 2-liang mandarin fish fry high?

Not high.

The survival rate of 2-liang mandarin fish fry is not high. This is because artificially cultivated fry cannot adapt well to the water environment of stocking, and there are many natural enemies and viruses of mandarin fish fry in wild rivers, resulting in a low survival rate.

Mandarin fish, also known as sweet-scented osmanthus fish and seasonal flower fish, is a freshwater fish of the genus Mandarin fish in the order Perciformes. Mandarin fish is about 28 cm long, spindle-shaped, relatively high, flattened laterally, with a raised back, a large head, an inclined mouth, a protruding lower jaw, which extends back to the rear edge of the eye, canine-like small teeth in the front of the upper and lower jaws, and a serrated rear edge of the preoperculum.

How much can mandarin fish grow in a year? Can it be raised in a reservoir of more than 100 mu?

Mandarin fish is scientifically known as Siniperca chuatsi, also known as Osmanthus fish, Seasonal flower fish, etc. It is a precious freshwater fish. There are many strains such as Siniperca chuatsi, Siniperca chuatsi, Siniperca chuatsi, and Siniperca chuatsi. Siniperca chuatsi grows the fastest, followed by Siniperca chuatsi. Siniperca chuatsi is a typical carnivorous fish that likes to eat live bait and often swallows live fish fry such as silver carp, grass carp, black carp, bighead bream, bream, and fine-scaled slender-jawed carp that are longer than itself.

Due to the scarcity of natural resources of mandarin fish, artificial breeding is restricted by technology and production development is quite slow. The market supply has been in short supply for a long time, so the breeding prospects are very promising.

Reproduction

The breeding season of mandarin fish is generally from mid-May to early July. Female fish reach sexual maturity in two years, while male fish reach sexual maturity in one year. Mature broodstock can reproduce naturally in rivers, lakes and reservoirs. They usually lay eggs on rainy days or in micro-flowing water environments, and the fertilized eggs drift with the water and hatch.

1. Broodstock cultivation Sexually mature broodstock must undergo intensive cultivation, which generally takes about half a year, with a focus on autumn and spring. Two points should be noted in intensive cultivation: first, there must be sufficient bait fish; second, good water quality must be ensured. It is best to flush the water regularly to create a micro-flowing water environment to ensure the good development of the broodstock. It should be particularly noted that before broodstock cultivation, the breeding object must be determined. Generally, the broodstock of Siniperca chuatsi should be selected for breeding to improve the economic benefits of breeding production.

2. Parent fish: Mandarin fish caught in natural waters or cultured in ponds. After artificial intensive cultivation, healthy individuals without disease or injury can be used as broodstock for artificial breeding. The weight of male fish is required to be 1-2 kg, and the weight of female fish is 2-3 kg. The difference between male and female mandarin fish is that the male fish has a long lower jaw that extends far beyond the upper jaw, with brighter body color and clear markings. When the abdomen is lightly pressed, semen flows out; the female fish has a short lower jaw that is almost the same length as the upper jaw. The characteristics of female fish with well-developed gonads are obvious ovarian contours on the abdomen, soft abdomen, prominent and swollen genital pores, and transparent yellow-green eggs. To judge whether the male fish is mature, it is mainly to press the abdomen lightly. If milky white semen flows out and disperses when it enters the water, it can prove that the gonads are well mature.

3. Artificial incubation The incubation method adopts loop water incubation. Since the fertilized eggs of mandarin fish are non-sticky semi-floating eggs and are larger than domestic fish eggs, the flow rate should be relatively large during the incubation to prevent the eggs from settling. The time for the fish eggs to hatch out of the membrane is closely related to the water temperature. In the loop water incubation, it takes about 28 hours when the water temperature is 24-28℃, and about 24 hours when the water temperature is 30℃.

Seedling cultivation

1. Pond cultivation

The fish fry pond should be thoroughly cleaned and 150 kg of quicklime should be used per mu to eliminate harmful organisms and pathogens. After the pond is cleaned, new water of 1 meter deep is added, and 200 mandarin fish fry are placed per square meter of water surface. Feeding mandarin fish fry with palatable feed according to different growth stages is the key to improving the survival rate of fry. Mandarin fish fry that have just hatched for 3-5 days are suitable for eating bream and bream fry of the same age. Mandarin fish fry of 6-8 days old can also eat fry of the four major carps of 3-5 days old. Mandarin fish fry of 9-15 days old can eat 1 cm long bait fish. According to production experience, when cultivating a 3 cm long mandarin fish fry (summer flower fish), the average daily intake of various fry is 40 fry in the first 10 days, and the average intake of fry slightly smaller than its own size is 15 fry in the last 10 days. If the number of bait fish is insufficient, the mandarin fish fry will kill each other. Therefore, while cultivating mandarin fish fry, the cultivation of bait fish fry should also be carried out. In actual production, the amount and type of feeding can be flexibly controlled to meet the feeding standard of mandarin fish fry.

2. Cultivation of mandarin fish fry in micro-flow water in fish ponds requires high dissolved oxygen. Therefore, small cement pools with micro-flow water can be used for cultivation where conditions permit, or spawning pools, loops and other equipment used in artificial breeding of domestic fish can be used. Generally, the area of ​​a small pond is about 20 square meters, and about 1,000 mandarin fish fry can be placed per square meter. It is necessary to ensure that the water quality is fresh and there is micro-flow water to keep the water in a state of regular exchange. When using artificial breeding loops to cultivate mandarin fish fry, the stocking density can be increased to 30,000 to 50,000 per cubic meter of water because of the large water exchange volume and rich dissolved oxygen. Because the water quality of the loop water is fresh and pollution-free, the operation and management are convenient, and there are few diseases, the survival rate of fish fry cultivated in this way of flowing water is relatively high.

3. Cage cultivation In water bodies with good water quality, cages can be set up for graded cultivation to improve the survival rate of mandarin fish fry. Generally, for the convenience of operation, a three-level cage cultivation method can be adopted: the mesh size of the first-level cage is 50 mesh, and the specification is 2m×1m×1m; the mesh size of the second-level cage is 0.2cm, and the specification is 5m×1m×1m; the mesh size of the third-level cage is 0.5cm, and the specification is 10m×1m×1m. The cage cloth is made of nylon or vinylon mesh, and the cage frame adopts a floating frame device. The density of mandarin fish fry stocked in the first-level cage is 10,000-15,000 per box; after about 15 days of feeding, the body length can reach about 1.8cm, and it can be transferred to the second-level cage for cultivation, and 1,000-2,000 can be stocked per box; after 7-10 days of feeding, the body length can reach about 3cm, and then it is transferred to the third-level cage, and the density is 500-1,000 per box. After another 15 days of cultivation, it will become a fish of about 10 cm. The key to cultivating mandarin fish in cages is to maintain clean water quality and sufficient palatable feed fish.

Pond culture

1. Fish Pond

Mandarin fish is suitable for breeding in small ponds. The area of ​​the fish pond is generally 1-3 mu, and the depth of the pond is about 1.5 meters. Before the mandarin fish fry are planted in the pond, the pond must be thoroughly cleaned. The commonly used drug is quicklime, 50 kg per mu; the amount of bleaching powder is 20 mg/L in the pond water. Generally, the drug properties disappear 10 days after the pond is cleaned. After filling the pond water in a bucket, put a few fish in. If there is no abnormality in 24 hours, you can release it. The stocking depends on the quality of the breeding conditions and the level of technology. Generally, 1000-1500 3.3 cm mandarin fish summer flower fingerlings are released per mu.

2. Bait fish: The natural diet of mandarin fish is live fish. There are generally three ways to get bait fish: one is to buy domestic fish and raise them intensively, and feed them at any time; the second is to cultivate and collect wild fish fry. Every acre of mandarin fish pond should be equipped with a bait fish cultivation pond of about 3 acres. Carp, crucian carp or some wild fish with early reproduction time and large reproduction amount can be put in to breed a large number of fish fry for mandarin fish to eat; third, in order to save fish ponds, some small fish such as wheat ear fish and silver carp can be directly put into the mandarin fish pond. The reproduction times are relatively large to meet the needs of mandarin fish.

3. Feeding To raise a 0.5 gram (3 cm long) mandarin fish fry to a 500 gram commercial fish, you need to consume about 5,000 bait fish (about 3 kg). Feed fish should be released in time according to the growth of the fish and weather conditions. It is best to release them once every 3-5 days to keep a certain density of bait fish in the pond. When there is sufficient bait source, you should try to add some bait fish so that the mandarin fish has enough food. The uneaten feed fish should be caught and sold together with the mandarin fish when fishing.

Fourth, management mainly involves patrolling the pond in the morning and evening to observe the feeding, growth and water quality of the mandarin fish. To maintain good water quality, keep the dissolved oxygen in the water above 5 mg/L. Generally, change the water once every two weeks, and flush the water in time when the water becomes concentrated. In the hot summer weather, an aerator must be used to increase oxygen. In order to avoid excessive water, certain aquatic plants can be cultivated in the water to purify the water quality, which is conducive to the growth of mandarin fish.

In addition, attention should be paid to preventing fish from escaping and theft. The inlet and outlet should be covered with silk mesh to prevent the fry from escaping with the water. During the adult stage and when the fish are about to be caught, someone should be on duty to prevent the theft of fish.

Network breeding

1. Free-range

The cage area for breeding mandarin fish is generally about 20 square meters. If it is too large, it will be inconvenient to manage, and if it is too small, the water quality will deteriorate easily. The mesh size is 2.5-3 cm. The cage should be set up in an environment with micro-flowing water, and the water quality of the reservoir is the best. The stocked mandarin fish are generally about 10 cm, and the stocking specifications should be uniform, otherwise the big ones will eat the small ones. Generally, they are stocked in April. About 15 fish are stocked per square meter, and they are caught in November. Each fish weighing more than 0.5 kg can be obtained.

Second, feeding. The most important thing for caged mandarin fish is to solve the problem of bait fish. The types of bait fish can be fed according to local conditions, such as bream, crucian carp, tilapia fry, etc., and a small amount of live earthworms can also be mixed in. The bait fish should be fed in small and frequent meals, and fed three times a day (once in the morning, noon and evening).

3. Management The density of cages for raising mandarin fish is high, so management must be strengthened. The cages must be cleaned and disinfected frequently, at least once a week. When cleaning the cages, first transfer the mandarin fish to the spare cages, thoroughly remove the debris and leftover bait in the cages, and brush off the moss on the cages to prevent clogging of the mesh. Disinfect the cages with quicklime once a month. In terms of management, you should also pay attention to whether there are holes in the mesh at any time, and if there are any, you should sew them up in time. In order to prevent water rats and other enemies from biting the mesh, you can hang a rubber wire mesh outside the cage to block the passage of the enemies.

Disease prevention

1. Saprolegniasis

During the breeding process of mandarin fish, if the hatching water of fertilized eggs is mixed with dirt, the eggs will be damaged and infected with water mold. The infected eggs have fluffy things growing on the outside of the egg membrane, which is similar to the water mold disease of "domestic fish". In severe cases, it will cause a large number of deaths. During the breeding process of mandarin fish fry, fingerlings and adult fish, the fish body is injured due to improper operation and transportation, which is easy to occur. The body surface and abrasions of the diseased fish are observed with the naked eye. There are white floccules. Once infected with this disease, the sick fish swims slowly, loses appetite, and finally dies of weight loss.

Prevention and control methods: (1) Use a 60-mesh nylon gauze screen to filter the water used to hatch mandarin fish to prevent foreign matter from entering. (2) Do not select injured fish as broodstock. (3) During the fry, fingerling and adult stages, soak the fish in 3% salt water for 5-10 minutes, or soak the diseased fish in 1% salt water with a few drops of vinegar for 5 minutes. In addition, prevent the fish from being scratched during fishing and transportation.

2. Ciliate disease This is one of the main diseases in the cultivation of summer flowers of mandarin fish. It is mainly caused by wheelworms and other parasites on the body surface, fins and head of mandarin fish. The disease spreads rapidly. When the number of parasites is small, it has little effect on the activity of the fish; when the number of parasites is large, the fish will not eat. White spots can be seen on the fish body with the naked eye, the mouth cannot be closed, the fish loses balance when swimming, and then dies. The disease is extremely harmful.

Prevention and treatment methods: (1) Pour 3% salt water into the pond once a day and stop the water for 3-5 minutes. This can play a preventive and therapeutic role. (2) When the summer flowers are put into the pond, soak the diseased fish in 2% salt water for 2 minutes.

3. Anchorhead and Chinese mullet diseases Anchorhead mullet mainly parasitizes on the surface of mandarin fish, causing the fish to lose weight and lose the ability to swim and hunt. Chinese mullet mainly parasitizes on the gills, destroying the gill tissue and affecting the breathing ability. This type of mullet mainly harms mandarin fish species, and the harm is relatively large. If two anchorhead mullets parasitize on the body of a 5-cm young fish, it can cause the young fish to die, so prevention should be carried out early in breeding.

Prevention and control methods: (1) Before stocking the pond, use quicklime and water to clean the pond to kill the mites in the water. Attention should be paid to the cleaning of water sources and feed at all times to reduce the source of infection. (2) The bait fish for mandarin fish can be soaked in 15 mg/L potassium permanganate for 2 hours to kill the mites on the fish body.

4. Gill rot and enteritis often occur in high temperature seasons. The gill filaments rot and have white spots, and dirt and mucus are attached.

Gill rot can be treated by soaking in 2 mg/L mercuric nitrate solution for 10 minutes, which can gradually alleviate the condition. The main symptoms of enteritis are congestion and swelling from the rectum to the anus, and light yellow feces. In severe cases, the entire intestine swells and turns purple, and the excrement is a thick liquid. The main cause of the disease is that the bait fish carries bacteria and is swallowed by the mandarin fish.