CATDOLL : CATDOLL: The most suitable growth environment for blackmouth carp

According to my understanding, it is relatively easy to develop blackmouth silver carp farming now. On the one hand, the technical requirements are relatively low and it only requires daily management. On the other hand, it is favored by farmers because of its low investment, quick results and high profits. Against the backdrop of the general downturn in my country's traditional aquaculture industry, the production and sales market is booming, making it a popular investment industry at present.

1. Silver carp is a pelagic fish. In spring, summer and autumn, it spends most of its time swimming in the pelagic layer of the water for food, and in winter it dives to deep water to hibernate.

2. It is a typical filter-feeding fish. Main food: Silver carp feeds on plankton throughout its life. In the fry stage, it mainly eats zooplankton. When it grows to more than 1.5 cm, it gradually turns to eating phytoplankton. It also likes to eat grass carp feces and chicken and cow dung. It also eats soy milk,

They prefer bean dregs powder, bran and rice bran, and prefer artificial micro-granular compound feed. They are very interested in sour food and have a strong appetite for rotten food. Silver carp's food has obvious seasonality. In spring and autumn, in addition to plankton, they also eat a lot of rotten bait; in summer, the lower the water level, the greater their food intake; in winter, they eat less and move less. It is suitable for breeding in fertile water. The length of the intestine is about 6-10 times the body length.

3. Appetite is proportional to water temperature. Silver carp likes high temperature, and the most suitable water temperature is 23℃~32℃. Silver carp has the strongest appetite in the hot summer. July to August in the north is a good time to fish for silver carp. After the autumnal equinox, the weather gradually cools down, and the appetite of silver carp decreases, making it difficult to catch.

4. They are lively, like to jump, and have the habit of swimming upstream, but they are not very agile and are rather clumsy. Silver carp likes fertile water, and similar individuals often gather in groups and swim to the middle and upper layers of the water, especially in clear water areas with fertile water.

5. They are timid and afraid of being disturbed. When disturbed or touched by the net wire, they will jump out of the water and escape over the net.

6. Fast growth and high yield. Silver carp reaches sexual maturity 1-2 years earlier than grass carp. Mature individuals are also smaller, and female fish over 3 kg can generally reach maturity. Female fish weighing about 5 kg can carry about 40,000 to 50,000 eggs per kg of body weight. They lay eggs in April and May every year, and the absolute egg carrying capacity is 200,000 to 250,000 eggs. The eggs are buoyant. The spawning period is similar to that of grass carp. Under pond conditions, if there is sufficient bait, the fish can grow to 500-800 grams in the same year, and the weight of three-year-old fish can reach 3-4 kilograms. In natural rivers, they can weigh up to 30-40 kilograms.

7. They have very poor tolerance to low oxygen levels. They will float to the surface immediately due to lack of oxygen in water, and some will die soon.

Farming

Edit this paragraph

Pond Selection

Silver carp is a type of fish that is cultured in conjunction with ponds that mainly culture carp, crucian carp, grass carp and bighead carp. It is in a subordinate position and the pond it is selected for is exactly the same as the main fish species for which certification is applied.

Water quality requirements

The water quality requirements for silver carp are exactly the same as those for the main carp for which certification is applied.

Seedling requirements

Before stocking, the seedlings must be inspected and quarantined to select those with pure quality, healthy and disease-free, and uniform specifications. The stocking time is mid-to-late May.

Pond breeding

1. Fish breeding

Stocking of fish fry: In mid-to-late May, when the water temperature in the pond is stable above 18°C, it is the appropriate time to stock. Stock silver carp and black carp at a density of 3-5 per square meter.

Feeding and management: After the fry are put into the pond, they mainly filter-feed on planktonic plants and animals and also eat feed debris.

Adult fish farming: fish stocking specifications and density. The specifications for overwintering fish are 100-200 grams per fish, and the stocking density is 0.4-0.5 fish per square meter.

Silver carp is a cultured fish and the time of catching is based on the time when the carp leaves the pond.

2. Winter management

Overwintering density: The overwintering density of adult fish and fingerlings in the pond is generally 0.3-0.6 kg/㎡, which can be adjusted appropriately according to the pond conditions.

Requirements for overwintering fish: The fish should be free of disease and injury, and be plump and strong.

Wintering method: Wintering ponds should be relatively clean, with good water retention, and the water depth under ice should be kept at about 1.5 meters. Pools should be divided into different specifications: Before freezing, 1.5-3.0 kg of 90% crystal trichlorfon per hectare should be used to spray the entire pond. The amount of phytoplankton in the pond water should be kept at 25-50 mg/l. To maintain the light transmittance of the water surface, the snow on the ice surface should be cleared in time, and ice holes should be drilled to observe the water quality and the activities of the fish. Fish disease prevention and control 1. Careful operation should be carried out during the process of pulling nets, screening, and transporting fry and fingerlings to prevent fish from being injured;

2. Before the fry and fingerlings are put into the pond, they should be disinfected by soaking them in 2.0% salt water for 5-10 minutes;

3. In hot seasons, disinfect the food court every month using bleaching powder or a mixture of copper sulfate and ferrous sulfate in hanging bags;

4. Regularly use microbial preparations to regulate water quality and improve fish immunity;

5. Dead fish should be fished out promptly and buried deeply;

6. Fish disease treatment. Prevention and control technology of silver carp diplodiasis Edit this section Diplodiasis belongs to the class Cestoda, family Schizocephala, genus Diplodia. The first intermediate host is copepods, the second intermediate host is fish, and the final host is fish-eating birds. In the past, some large and medium-sized reservoirs occasionally found it in crucian carp and wild fish, often concentrated infection, with a tendency to spread. It mainly causes great harm to one-year-old silver carp species, with the highest pond infection rate reaching 92%. When the infection intensity is the highest, there are 13 schizocephala in the body cavity of each silver carp. The highest mortality rate of diseased fish species during wintering is 84%. However, the infection is not consistent in each year, which is mainly related to changes in the water environment (reduction of water area due to drought) and the activities of water birds. This article analyzes the causes of the disease and proposes prevention and control measures.

1. Symptoms of sick fish

The diseased silver carp have a swollen abdomen with a bulge in some parts. After the ice melts in early spring, they become noticeably thinner, with a more swollen abdomen. The abdominal muscles are extremely thin, and if you squeeze the abdomen hard, the sparganum can come out from the pectoral fins. Most of the diseased fish die during the process of netting and transportation, and only a few survive. The main susceptible host of the two-line tapeworm is the silver carp, while the common carp species are mostly infected with the sparganum of the tongue-shaped tapeworm.

2. Cause Analysis

1. Ponds near reservoirs, swamps, or ponds with open water and few people in a secluded environment. From spring to autumn, many water birds such as herons, red-billed gulls, and kingfishers often stay and roost here, swimming between reservoirs and fish ponds. The high infection rate of sparganosis often occurs in large wintering ponds. When the ice on these ponds melts in spring every year, sick or weak fish often swim on the water surface, attracting a large number of water birds to prey on them, and their feces containing worm eggs are discharged into the water, causing infection.

2. After selling out spring fish, some ponds are filled with water to raise water flower fish fry because of time constraints and no time to clean the pond. Some ponds (shallow ponds with water) are frozen through in winter, and they think that the purpose of pond cleaning has been achieved, so they put summer flower fish fry soon after filling with water. The first intermediate host of double-line tapeworms (copepods) can hibernate with eggs as adults. The dormant bodies can survive various harsh environments such as drought and freezing. The number of dormant bodies can reach hundreds to millions per square meter, and they are often highly concentrated in a small area. Because copepods have this adult dormancy adaptability, once new water is injected into the fish ponds that are not cleared with drugs, a considerable number of sexually mature copepod adults with eggs will soon appear. The author saw a large number of adult copepods with eggs in some very shallow puddles in winter shortly after the ice and snow melted in early spring, which also shows that adult copepods can resist harsh environments. In summary, in some ponds, due to the lack of drug cleaning, a large number of dormant copepods are hidden in the water, which lays a hidden danger for infection with double-line tapeworm disease.

3. According to the biological characteristics of fish fry, when water flower fish fry enter the summer flower stage, their feeding habits will change from rotifers to larger zooplankton. Some fish farmers consciously cultivate some cladocerans and copepods for summer flower fish fry in the pond. However, if there is no artificial control, copepods are likely to become the dominant population. Since copepods are specific in swallowing nematodes, if there are water birds carrying pathogens near the pond at this time, summer flower fish fry are very likely to be infected with double-line tapeworm disease.

4. Some fish farmers purchase summer flower fish fry infected with sparganosis from areas prone to tapeworms. Even if the local conditions for tapeworms are not met, the fish fry have already swallowed copepods infected with procercariae, which develop into sparganosis in the fish body cavity and are excreted at the same time, resulting in the same size of the stocking pond.

Infection with dipteraphidosis.

3. Prevention and control measures

First of all, we must take good care of the fry. If the fry are transported from other places, we should first investigate whether the fry supplier has a history of tapeworm disease. If you are raising summer flower fry yourself, and there is a history of tapeworm disease in the local area, or there are water birds, then the first intermediate host and copepods must be killed before the fry are put into the pond. Copepods found during the pond development should also be removed. In addition, we must enhance awareness of bird protection, study effective methods that do not harm the life of the final host, and drive away water birds. In areas where tapeworm disease is prevalent, we must insist on using quicklime to clean the pond. Commonly used drugs edit this section Jiachongqing

Main ingredients and content: Rhubarb

Appearance: Yellow-brown powder, fragrant smell

Function and use: Sterilization and insecticide. Mainly used for ciliates such as wheelworms and oblique tubeworms.

Usage and Dosage: When the disease occurs, spray 100-200 g/mu/m2 throughout the pond for 1-2 consecutive times.

Withdrawal period: 30 days

Insect Sweep

Main ingredients and content: 2.5% dithiocyanatomethyl.

Appearance: Brown liquid

Function and use: Sterilization and insecticide. Mainly used for ciliates and worms fish parasites.

Usage and dosage: When the disease occurs, add 130ml-170ml/mu/m2 of water and spray the whole pond. If the disease is serious, it can be used again every other day.

Note: Do not use other insecticides or fungicides within four days before or after use.

Withdrawal period: 30 days

Bacteria and Virus Clearing

Main ingredients and content: Sodium chlorite, 80%.

Appearance: White powder or granules

Function and use: Sterilization and insecticide. Mainly used for hemorrhagic disease, gill rot, enteritis, vertical scale disease, Saprolegniasis, etc.

Usage and dosage: When the disease occurs, add 0.37-0.5ppm of water and spray it all over the pond. If the disease is serious, it can be used again every other day.

Note: Mix A and B solutions in the open air and use them immediately after preparation.

Withdrawal period: 10 days

Bromine-rich hydantoin

Main ingredients and content: Dibromohydantoin, 30%.

Appearance: White powder

Function and Use: Sterilizer. Mainly used for hemorrhagic disease, gill rot, enteritis, vertical scale disease, Saprolegniasis, etc.

Usage and dosage: When the disease occurs, add 0.3ppm to water and spray the whole pond. When the disease is serious, double the dosage or use it for 2 consecutive days.

Withdrawal period: 10 days before fishing

Probiotics

Main ingredients and content: Bacillus, photosynthetic bacteria, nitrifying bacteria, nitrogen-fixing bacteria, etc. The number of live bacteria is > 70 billion/gram.

Appearance: Gray brown powder

Function and use: Water quality improver. Remove organic pollutants, ammonia nitrogen, nitrite and other harmful substances in aquaculture water, increase dissolved oxygen in water, and adjust pH value.

Usage and Dosage: Based on the deterioration of water quality, soak 200g-300g of the product in water per acre at a depth of 1 meter and then sprinkle it over the entire pond.

Note: Do not mix with disinfectants or insecticides when using; do not use disinfectants 3 days before and after application. Soaking time in water for 1-2 hours is beneficial.

Symptoms: The sick fish does not eat, swims slowly, the gills are congested and bleeding, the gill petals are a little congested, and lose their normal bright red color and become pink or pale. In severe cases, the gill filaments are necrotic, affecting the respiratory function and leading to the death of the sick fish.

Prevention and treatment methods:

1. Thoroughly clean and disinfect the pond to keep the water clean and prevent water quality from deteriorating

2. To cultivate water quality, it is necessary to apply fermented and humus organic fertilizer, and it is not suitable to apply raw fertilizer.

3. The diseased pond should be quickly filled with clean water to improve the water quality, or the diseased fish should be transferred to a pond with fresh and clean water.

4. Spraying 20-30 mg/l of quicklime throughout the pond can reduce the content of organic matter in the water and improve water quality.

Printing Disease

Pathogen: Aeromonas hydrophila and Aeromonas sobria

Symptoms: The diseased fish has a nearly circular red spot on the body surface behind the dorsal fin. The scales fall off at the lesion, and eventually ulcers form and even bones or internal organs are exposed.

Prevention and treatment methods:

1. Since the feces of herbivorous animals (such as cattle and sheep) are the breeding grounds of Bacillus, it must be mixed with quicklime and fully fermented when applied to fish ponds. It can only be applied after it is rotten and hot to prevent pathogens from entering.

2. When fish are transferred to the pond, they can be soaked in 2% salt water for 5-10 minutes to effectively prevent this disease.

3. Use external disinfectants when you are sick. External disinfection: Spray 0.5ppm of Bacteria and Virus Clear or 0.3ppm of Dibromohydantoin throughout the pool.

Dactylariasis

Pathogen: Dactylorhiza

Symptoms: When the disease is serious, the gill filaments of the diseased fish are swollen, the mucus increases, and breathing becomes difficult, which can cause the death of a large number of seedlings.

Prevention and treatment methods:

1. Spray 0.3-0.7ppm of 90% crystalline trichlorfon throughout the pond.

2. Spray the whole pond with 130ml-170ml/mu/m of insect sweeper. If the disease is serious, use it again every other day.