Small cement ponds are generally selected for aquaculture ponds, with a water depth of 0.6m- 1m and an area of 8m2- 10m2.

The slope of the pond wall is slightly larger, which is convenient for tadpoles to rest on the pond wall and for abnormal young frogs to land.

Because the newly hatched tadpoles are only 5 mm -6.3 mm long, their swimming ability is poor, and they mainly rest by sucking attachments with suction cups. Water hyacinth, aquatic plants, tree roots, etc. Should be put into the pool, covering 1/3.

The pool is wrapped with bamboo foil to prevent the enemy from destroying it, and a bait table is set under the water surface 10 cm in the pool.

Rana bullfrog stocking density

The newly hatched tadpoles can be properly kept and managed, and 2,000-3,000 tadpoles can be raised per square meter.

After 10 days old, with the growth of individuals, the feeding ability is enhanced and the density is gradually reduced. Generally, 500- 1000 are raised per square meter, and 30 days before metamorphosis, 500-100-300 are raised per square meter.

When stocking, soak in 3% salt for 5 minutes and disinfect.

Food intake of bullfrog

During the first 6 days after hatching, tadpoles mainly rely on the yolk sac in the body to provide nutrition. Six days later, with the disappearance of yolk sac, they began to eat plankton and artificial bait. Fertilization before breeding can cultivate plankton, solve the problem of feeding tadpoles and improve the survival rate of tadpoles.

Artificial bait mainly includes snails, fish, animal offal, Daphnia, bean cake, rice bran and so on.

Feeding amount: every 7-30-day-old tadpoles 1000 are fed with 40-70 grams of bait every day, of which animal bait accounts for 70%; From 30 days later to before metamorphosis, every 1000 tadpoles were fed with 60-80 grams of bait every day, of which animal bait accounted for 57%.

Powdered feed should be cooked and kneaded into balls, fish intestines should be chopped and snails should be crushed.

The daily feeding time is 16 hours to 17 hours.

Daily management of bullfrog breeding

In the process of culture, change the water every 3-5 days, each time 10 cm- 15 cm, and the temperature difference of water does not exceed 3℃ each time, and clean the food table regularly every day.

Tadpoles are bred into young frogs after 80 days-1 10, and the mortality rate before metamorphosis is high. Therefore, it is necessary to strengthen management, stop feeding, keep the environment quiet, and strive to improve the survival rate of tadpoles during metamorphosis.

Carnivorous fish, dragonfly larvae, water snakes, tiger frog tadpoles and lice larvae will devour bullfrog tadpoles, and they should be removed in time once they are found.

Feeding management of bullfrog tadpoles

Tadpole is the larval stage of bullfrog's individual development and also the larval stage of production process, so it is the material basis of bullfrog's production.

The quality of tadpole breeding not only directly affects the growth, size and quality of tadpoles, but also has a close relationship with the quality and survival rate of metamorphosed young frogs in the future.

Therefore, it is a very important work in bullfrog breeding production, which is of great significance to the success or failure of bullfrog breeding.

1. Tadpole culture pond

At present, there are two kinds of ponds for raising tadpoles: cement ponds and soil ponds.

Because of the convenience of digging and low cost, most of them use soil ponds, while cement ponds are mainly used for intensive farming with high density and high yield.

1. Cement pool area 1 .5 ~ 20m2, pool depth1m, and water storage depth of 80cm.

Advantages of cement pool: clear water quality; The wall of the cement pond is suitable for tadpoles to rest on in the early stage, which can avoid tadpoles from suffocating and dying because of being covered with sediment at this stage. Daily management such as changing water is convenient, and the survival rate is high, generally reaching 70% ~ 90%. The density of stocked tadpoles is high and the yield is high.

However, due to the high stocking density, the tadpoles produced are small, and the young frogs are also small, only 4 to 5 grams; Deformed young frogs can't land in time, and if they are not caught in time, they will die in large numbers. The cost is relatively high, and the one-time investment is relatively large, which is the deficiency of the cement pool.

2. The soil pond has an area of 50 ~ 100 square meter, a depth of 0.8 ~ 1 m, a water storage depth of 60 ~ 80 cm, and a slightly steep slope around it. The suitable ratio is1:1.5 ~ 2, which can ensure the dike body to be firm and is suitable for tadpoles to be transformed into young frogs.

The advantages of the earth pond are: the water body is relatively large, the water quality is relatively stable, the cultured tadpoles are large, and the abnormal young frogs are also large, mostly at 7 ~10g; However, management is difficult, there are many enemies, and the survival rate is relatively low, generally only about 50%.

Second, the preparation work before stocking tadpoles

1. Tadpoles that have just hatched after the time of raising tadpoles have poor adaptability to the external environment. At this time, the digestive organs are not connected, and the yolk sac in the abdomen provides nutrition and does not need to ingest external food.

Therefore, the newly hatched tadpoles should not be moved to the tadpole pool immediately, and should be moved to the tadpole pool when the yolk sac in the abdomen is completely absorbed and the digestive organs are completely connected, or when it is observed that they have been discharged at the beginning.

As for the specific time, it depends on the water temperature at that time: that is, when the water temperature is 18℃ ~ 20℃, it is about 180 ~ 200 hours after hatching, and when the water temperature is 20℃ ~ 25℃, it is about 150 ~ 170 after hatching.

2. Cleaning and disinfection of the cement pool for tadpoles Two days before the tadpoles are released, the bottom and walls of the pool should be coated with bleached toner with a concentration of 1ml/l or quicklime solution with a concentration of 20ml for disinfection, then exposed to the sun for 1 ~ 2 days, and then put into clean water before the tadpoles can be released; The newly dug cement pond should be soaked in water for dealkalization two weeks before use, and then replaced with new water before tadpoles can be stocked.

For the earth pond, the pond should be cleaned with quicklime or bleached toner 10 ~ 15 days before the tadpoles are released.

The dry pond method usually uses quicklime to clean the pond, that is, drain the pond water of 5 ~ 10 cm, then dissolve 90 ~10 g of quicklime in the water per square meter, and spread the lime slurry all over the pond. Only after 7 days of pond cleaning can tadpoles be released. When cleaning the pond with bleaching powder, the dosage of bleaching powder is 7.5 ~ 15g per square meter. After being dissolved in water, the tadpoles can be scattered all over the pond, and the tadpoles can be released in the water within 3-5 days after cleaning the pond.

3. In natural water, the tadpoles of bullfrog injected with basic fertilizer mainly feed on plankton.

Therefore, when raising tadpoles in soil ponds, base fertilizer should be applied and plankton should be cultivated before stocking.

That is, seven days before the tadpoles are stocked, the tadpole pond is filled with water for 30-40 cm, and then cattle, horse manure, human manure or green manure are piled up in the shallow water area about 1 m away from the shore of the pond, and the fertilization amount is 0.5 kg per square meter.

After fertilization, plankton will multiply rapidly, so that tadpoles can eat rich and palatable bait and grow rapidly.

In the cement pool, because fertilization will destroy the water quality and cause tadpoles to suffocate and die, the cement pool can not be fertilized and can only be fed with artificial bait.

Third, tadpoles are stocked.

The stocking density of tadpoles should be determined according to many factors such as feeding conditions, feeding methods, bait, tadpole size and feeding management level.

Generally, the density of tadpoles can be higher when they are first stocked, with a total length of 1.2 cm and 800 ~ 1000 tadpoles per square meter. When the total length is 3 ~ 4 cm, it will be diluted to 300 ~ 400 tails per square meter; When the total length is 6 ~ 7 cm, it should be diluted to 150 ~ 200 per square meter.

Because of its superior management and water exchange conditions, the stocking density of cement pond is 1 ~ 2 times higher than that of soil pond.

Fourth, feeding management.

The management of tadpoles is mainly to control the water temperature, adjust the water quality and feed them reasonably.

When the water temperature is as high as 32℃, the activity ability of tadpoles decreases, the food intake decreases and the growth is inhibited. At 35℃, tadpoles were extremely weak and began to die. At 38℃, a large number of deaths will occur.

Therefore, in hot summer, cooling measures must be taken.

A shade frame should be built above the cement pool, and vines such as grapes or melons should be planted to shade and cool down; For the earthen pond, due to its large area, a sunshade frame can be set for the half pond facing south, and climbing plants can also be planted for shading. Author: Jiangsu Freshwater Fisheries Research Institute cools down.

In addition, in places with water sources, fresh water can also be added to the outer river to cool down.

The water quality is closely related to the growth and survival rate of tadpoles.

Therefore, water should be added or changed according to the change of water quality during tadpole culture.

Topdressing should also be carried out according to the water quality of the soil pond, roughly every 3 ~ 7 days 1 time, and every time per mu 150 ~ 200 kg.

When fertilizer and plankton are insufficient, artificial bait should be properly fed.

Artificial feeding is mainly used in the cement pond, generally every morning and afternoon 1 time, and the daily feeding amount is about 2% ~ 10% of the total weight of tadpoles.

Verb (abbreviation of verb) The growth, development and metamorphosis of tadpoles.

The growth and development speed of tadpoles mainly depends on water temperature and nutritional conditions.

According to the results of feeding in cement pond, the density is 600 animals per square meter, and the water temperature changes from 22℃ to 30℃ during feeding. After 27 days of incubation, the total length is 4.9 cm and the weight is 65438 0.4 g, and the hind limb buds grow. 5 1 day after hatching, the total length is 9. 1 cm, the weight is 8. 1 g, and the hind limb is 0.4 cm long; 8 1 day after hatching, the total length is 10.3 cm, and the weight is 8.3 g. The left forelimb extends first, and the right forelimb also extends through the cortex gill cover the next day, and the mouth crack is deep, and then the tadpole tail gradually absorbs and shortens. 88 days after hatching, the tail is completely absorbed and transformed into a frog.

Tadpoles are in the most dangerous period of metamorphosis, and a little negligence in management will cause a lot of deaths.

At this time, more aquatic plants such as water hyacinth and Eichhornia crassipes or floating objects such as wooden boards should be put in the cement pool for abnormal young shellfish to rest. At this stage, no matter the cement pond or the earth pond, the abnormal young frogs should be caught in the young frog pond in time.

Running water culture method of bullfrog

In 2003-2004, Nan 'an Water Technology Station conducted a running water culture experiment of bullfrog under Guokeng Reservoir in Honghai Town, that is, using natural running water with different mountain topography for 24 hours. The actual aquaculture water area is 10 mu, and 230,000 young frogs are cultivated, with a survival rate of 43.5%. The single-season yield is10.5 million kg, and the output value is 2 1.

The main techniques of flowing water culture of bullfrog are introduced as follows:

1, choose the site

General requirements for farms: adequate water sources and convenient irrigation and drainage; The water quality shall be pollution-free and conform to the fishery water quality standards; Warm in winter and cool in summer, away from noise; Convenient transportation and sufficient power supply are beneficial to aquaculture production.

Among them, the quality of water source conditions is the key to the success or failure of raising frogs.

Step 2 build a frog pond

Take1002 as a large pool, and then divide each large pool into four small pools on average.

The edge of the pool is surrounded by a 40-mesh screen, the screen wire is higher than the bottom of the pool 1m, and the bottom of the screen wire should be buried in the soil for 20-30cm；; Ridge height 40cm, slope 1∶3, water level 30-40 cm, water depth not less than 20cm, otherwise the water storage capacity is too small, the water is turbid, and bullfrogs are easy to get sick. In order to facilitate operation, a rectangular pool should be adopted; The water supply and drainage pipes are made of plastic pipes with the diameter of 10- 12 cm, and the positions of water inlet and overflow holes should be set at the diagonal of each large pond; Four 80×40cm floating white foam plastic plates are placed in each pond as a rest platform for bullfrogs; The swimming pool is covered with a black sunshade net to prevent the sun from being exposed in summer.

Step 3: stockings

Before the seedlings are released, the dry pond is disinfected with 50-75 kg of quicklime or bleaching powder 10- 15 kg (about 30% of available chlorine) per mu.

Generally, seedlings can be released after 10 days of cleaning and disinfection.

Before stocking, young frogs can be soaked in 20ppm potassium permanganate solution 10-20 minutes.

When soaking, personnel should be present to observe, and the frog seedlings should be taken out immediately if abnormal conditions are found.

The stocking density of young frogs is 60-80 /m2, and that of adult frogs is 30-40 /m2 with the change of individual differences.

4. Feeding management

(1) patrol pool view

Patrol the pond once a day in the morning, at noon and at night to check whether there are holes in the screen mesh. If it is damaged, it must be repaired immediately to prevent the bullfrog from escaping, ensure uninterrupted running water for 24 hours, and achieve at least 300% water change rate every day; The water level can be controlled by lifting the plastic sleeve of the overflow port. Generally, the water depth is kept at 30-40 cm, and the water quality is kept fresh.

It should also be observed that if the feeding and activities of bullfrogs are abnormal, corresponding treatment measures should be taken in time.

(2) Feed feeding

The floating compound feed is mainly used, and the compound feed is soaked with clear water half an hour before feeding, so that the feed is slightly softened and expanded, which can prevent the sewage in the bait suction pool, eliminate the gastrointestinal diseases of the bullfrog after eating, and also promote the absorption of nutrients by the bullfrog.

The daily feeding amount should be kept at 7- 15% of the frog's weight. Besides the frog's weight, the feeding amount should be adjusted according to the climate, water quality and residual bait, so as to achieve less times.

The feeding amount should be eaten in half an hour.

(3) Graded feeding

In the process of bullfrog breeding, in order to prevent the same species from cannibalizing each other, individuals with different specifications should be screened and graded every once in a while, and bullfrogs with the same specifications should be adjusted to the same pond for breeding, so as to prevent big frogs from eating small frogs, and at the same time, pay attention to controlling the breeding density.

(4) Prevention and treatment of diseases

In the process of bullfrog breeding, it is necessary to give priority to prevention and combine prevention with control.

Disinfect the pond before stocking, and disinfect it with quicklime or bleached toner to kill pests and pathogens; Spray bleaching powder or strong chlorine essence in the swimming pool regularly for disinfection; Disinfect the frog body with 20ppm potassium permanganate in time after dividing the pool to prevent mechanical damage from spreading pathogens; Find out the isolation of sick frogs and dead frogs in time. In addition, the tools are disinfected with high concentration bleaching powder or potassium permanganate solution.

Control the reasonable breeding density.

Bait feeding should be "four fixed", that is, fixed point, fixed time, quantitative and qualitative.

When adult frogs are raised, individual bullfrogs with crooked heads and red legs appear. Pick out the crooked bullfrog, isolate it in time, disinfect it continuously with 15ppm strong chlorine for 5 days, and increase the change of water.

Management measures of bullfrog in summer

Summer is the "golden age" for bullfrog growth, and its management measures mainly include the following points.

1. Increasing the feeding amount With the increase of temperature, the feeding amount of bullfrog will gradually increase to avoid the phenomenon of the jungle in the feeding pool. At this time, the feeding amount should generally reach about 20% of the total weight of frogs.