What is the ripening and fattening technology of river crabs? How to scientifically promote the earl

Crab. In order to ensure the best amount of river crabs at this time, and at the same time avoid a large number of National Day river crabs on the market leading to a decline, according to the characteristics of the gonad growth of river crabs, the following measures can be taken to promote the early maturity of river crabs. Increase the proportion of animal bait to be fed.

After the last molting of river crabs, the proportion of animal bait feeding should be increased immediately, and animal bait is generally required to account for more than 60%, and animal bait is used as small trash fish and live fly maggots.

etc., while increasing the number of feedings. Slowly reduce the depth of the pool. When the water temperature drops to 28, that is, the depth of the pool water is slowly reduced, dropping by 5 cm per day, increasing the accumulated temperature of the pool water and promoting the rapid maturity of river crabs.

Removal of pond aquatic weeds. After the last molting of the river crab is completed, the pond aquatic weeds are removed to improve the activity of the river crab, but attention should be paid to prevent the change of water quality caused by the removal of aquatic weeds, and biological water quality and substrate improvers are applied every 5 days to regulate the water quality and substrate. Increase dissolved oxygen in the water body.

Insist on turning on the aeration equipment for 3-4 hours every day to ensure that the dissolved oxygen in the pond water is sufficient to promote the metabolism of river crabs.

Maintain high dissolved oxygen. In the later stage of breeding, the load pressure of the pond is getting bigger and bigger, and the accumulation of a large number of rotten grass, residual bait, and feces at the bottom of most ponds leads to black and smelly, and the oxygen consumption at the bottom of the pond is serious, and the temperature is getting lower and lower after the beginning of autumn, and the temperature difference is gradually increasing, and the pond is easy to return to the bottom of the hypoxia. Once the dissolved oxygen in the water body is insufficient, it is easy for river crabs to crawl on the grass.

Optimize feeding and adjust the bait structure. Ice fish, high in egg white.

With energy feed such as boiled corn, wheat, etc., a batch of snails can be fed after molting to supplement animal bait. Feeding should be insisted on every day, not as you like, in order to ensure that the river crabs are full and there is no leftover.

Reasonable feeding, to ensure adequate nutrition of the river crab fattening period is best to feed the protein content of more than 32% of the crab special material, the daily feeding amount is about 10% of the total amount of crabs, the actual production to feed 2 3 hours after the basic food shall prevail, with the gradual decline of air temperature and water temperature, the daily feeding amount should be gradually reduced. The feeding time is generally in the evening, supplemented by the early morning.

To ensure the health of the body of the river crab fattening period to the prevention of pests and diseases should be unremitting, prevention to the end, especially for the prevention of ciliarisis, to take the combination of "external elimination" and "internal administration" to prevent the occurrence of pests and diseases. Chlorine dioxide can be used 10 days after the last shelling of river crabs.

Wait for the whole pool to be splashed 1 time, and at the same time, you can add disease prevention and treatment crabs to the feed and feed them with drugs and bait, and feed them for 5 or 7 days.

What is the ripening and fattening technology of river crabs? How to scientifically promote the early maturity of river crabs? Insist on turning on the aeration equipment for 3-4 hours to ensure that the dissolved oxygen in the pond water is sufficient to promote the metabolism of river crabs.

Increase the proportion of animal bait to be fed. Appropriately lower the water level of the pond and increase the water temperature at the bottom of the pond. Generally, the precocious maturity of river crabs is formed by high temperatures.

First, reasonable water change, to maintain good water quality pond in the process of summer breeding disease prevention and treatment of drugs, it is inevitable that there are some residual substances, to the autumn to change the new water, to prevent the pool water from deteriorating, to maintain the transparency of the pool water Second, reasonable feeding, to ensure adequate nutrition of the river crab fattening period is best to feed the protein content of more than 32% of the river crab special material, the daily feeding amount is about 10% of the total amount of crabs, the actual production to feed 2 3 hours after the basic food shall prevail.

The first is to catch the crab dry pond as soon as possible, prepare the pond, and purchase the crab seed into the pond before the year; The second is to carry out river crab breeding, postpone the sales time and wait for a higher **, and some farmers will even raise river crabs until around the Spring Festival. Regardless of the sales template return or key suffocation breeding plan, there are problems such as winter river crab damage and safe overwintering, especially the harsh winters brought about by the El Niño phenomenon in several years.

You can give river crabs more high-protein food, and they can be sold after pressing, which can make the ** relatively higher.

1.Choose high-quality crab seedlings. High-quality local crab seedlings or reliable crab seedlings are preferred, because local crab seedlings are more suitable for the local water quality and climate environment.

Culling early-maturing crabs. It is required that the crab seedlings have complete limbs, clean shells, good color of liver and pancreas, and clear food lines. If conditions permit, crab seedlings can be fortified in autumn to accumulate enough nutrients for wintering.

2.Fortification should be done when the weather is suitable. The degree of nutrient accumulation and physical constitution of overwintering crab seedlings is one of the key factors for the success of the first molt.

Therefore, in early winter or early spring, when the water temperature is higher than 10, high-quality compound feed should be appropriately fed according to the crab activity, and the crab seedlings should be continuously strengthened in the low temperature season.

(1) The main cause of early-maturing crabs.

The breeding pond is too large: the breeding pond is small and suitable, the juvenile crabs are relatively concentrated, the bait is easy to be evenly fed, the higher the chance of each crab getting the bait, and the specifications are relatively more uniform and neat. The larger the pond, the more scattered the young crabs, the bait feeding can not achieve full coverage, over time, the crab species will gradually appear a situation of greater differentiation of specifications, the small ones become lazy crabs, and the large ones become early-maturing crabs.

The density is too low: the density of juvenile crabs is too low, which is easy to cause overnutrition of crab species, the size is too large, and the proportion of early-maturing crabs is greatly increased.

Over-feeding of bait: If the bait is too fine, especially if there is too much animal bait, coupled with the abundance of natural bait in the cultivation pond, the juvenile crabs that are gluttonous by nature are overnourished and form early-maturing crabs.

Increase of effective accumulated temperature: the water body of crab breeding species is small, the water level is shallow, the water temperature rises quickly, and the water temperature is always high in the continuous high temperature season, which accelerates the growth and gonad development of young crabs and forms early-maturing crabs.

2) Measures to control early-maturing crab species.

Simulate the natural ecological environment: plant some aquatic plants in the seedling pond, such as water peanuts, etc., and the area can be 1 3 of the water body. Aquatic weeds can not only be used for crab seedlings to feed, conceal attachment and shelling, and cool down, but also can breed many aquatic animals in the aquatic weeds, increase the natural bait of crab seedlings, and at the same time, aquatic weeds can also absorb fertilizer water and play a role in purifying water quality.

Master the feeding method: when the big-eyed larvae go to the pond, the water should be fertile, cultivate an appropriate amount of plankton, and the bait should be fine at both ends and green in the middle. That is, the early and late bait should be fine, and the middle stage should be green.

Specifically, in April and May, young crabs are mainly fed with some surimi and granular bait concentrate. In July and September, it is necessary to feed less concentrate and more palatable aquatic plants, such as Ladywood, when the weather is hot, river crabs like to eat plant-based bait. Therefore, it is necessary to replace the fine with coarse, which not only saves the cost of bait, but also controls the early maturity of crab seedlings.

After October, the temperature gradually drops, and the crab seedlings stop molting, during which they must be mainly concentrated, so that the seedlings can survive the winter.

Do a good job in injection and drainage: continuously improve water quality, increase water level, increase dissolved oxygen, and control fertilizer.

Adjust the pH of the pond water: the optimal pH for the growth of crab seedlings should be maintained. Quicklime should be applied twice a month for disinfection, generally 15 kg per mu is applied, which can not only adjust the water quality, but also prevent seedling diseases.

Conditions of adult crab rearing ponds:

Convenient transportation and quiet environment; The water source is abundant, the water quality is good and pollution-free, and the drainage and irrigation are convenient; The bottom of the pool is flat, and the slope ratio of the pond is 1:.

Anti-escape facilities: There are three main forms: cement brick wall, calcium-plastic board fence and polyethylene mesh fence. At present, calcium-plastic fences are commonly used, and the calcium-plastic boards are buried in the soil 20 cm along the perimeter of the ridge and compacted, and the interval is 1 meter and fixed with wooden piles.

Sterilization and disinfection of the pond:

Remove too much silt, only leave about 10 cm of silt, splash the whole pond with quicklime, the amount per mu is 200-250 kg, to achieve thorough pond disinfection, remove impurities and remove wild, kill germs, improve the substrate, 7 days after the medicine, that is, 1 time of water to eliminate dirt, and then add water after 3-5 days of drying the pond.

Aquatic plants suitable for planting in crab ponds:

Breeding a pond of crabs, first of all, we must plant a pond of grass, aquatic plants are one of the natural baits that river crabs like to eat, and can play a good role in purifying water quality, and it is a place for river crabs to inhabit and avoid enemies. The area of aquatic plants should account for more than 70% of the pond area, and the main varieties are melanophyllum rotifolia, bitter grass, elophyllum and so on.

Screws should be put in the crab pond:

Screws are one of the natural baits that river crabs like to eat, and they can purify water quality. Before the stocking of crab seeds, and the market and harmony, 300-500 kg of fresh screws are put into each mu to cultivate the basic bait of river crabs.

Otherwise, the water contains a large number of bacteria, which will affect the growth of crabs and even breed diseases. Changing the water in the pond frequently not only improves the water quality, but also facilitates the growth and shelling of river crabs. It is best to change the water in the pond every ten days, and the water in the pond is about 30% of the total water volume in the pond.

The second is to ensure that the nutrition of the crab is comprehensive, and when feeding the river crab, it is necessary to pay attention to some details.