What problems should be avoided when choosing large scale crab seedlings?

In the past two years, with the maturity of aquatic weed conservation technology and the improvement of breeding density, the value of large-size crabs can be raised into larger-sized adult crabs has been increasingly recognized by crab farmers. Therefore, many crab farmers who want to raise large-sized high-quality crabs are keen to choose 30-60 large-scale buckle crab seedlings. Although it has become the consensus of the industry to develop large-scale high-quality crabs, why do many crab farmers choose large-scale crab breeding, but the ideal Dacheng crab has not grown up for a long time?

The emergence of different factors such as weather diseases and nutrition will lead to some now, old seedlings, young seedlings, and diseased seedlings, therefore, when purchasing seedlings, you should choose individual uniform, traditional body clear, no broken limbs, no enteritis performance characteristics in the abdomen, good vitality of seedlings, from the appearance of the important body abdomen intestinal redness, disintegration in the dark, if crawling on the aquatic plants quickly, disturbed quickly dive into the bottom of the pond that is a healthy solution to the seedlings.

Pit 1: Large-sized buckle crab species raised in coastal low-salinity waters, this crab species is precocious, even if the environment is good, in practice, it is difficult to raise large-size adult crabs.

2 pits: shallow water seedling pond (water depth of about 50 cm) raised out of the large-sized buckle crab, this crab seedling breeding period breeding accumulated temperature is high, adult crab breeding period, high early maturity rate, can raise large-size boutique crab proportion is small, the number is small.

3 pits: small parents and big eyes raised large-sized buckle crabs, this kind of crab species, due to genetic reasons, large buckle crabs have high maturity (the number of molts is reduced), the doubling rate is small during the grow-out period, and it is difficult to grow large-sized boutique crabs.

4 pits: high maturity of large-sized buckle crabs, this kind of crab species is close to the old crab, because the second year molt 2--4 shells to mature, it is also difficult to raise large-size crabs, the main identification method is through the comprehensive assessment of the coverage rate of the abdominal carapace and the villi of the large chelella.

<> buckle crabs cultured in greenhouses should not be bought in coastal areas, and the greenhouses should be used to breed big-eyed larvae to early juveniles (i.e., early larvae) in the current year, and the early larvae should be used to breed adult crabs in the same year. Although the size of this breeding model is not large, the yield is very high, the survival rate is high, and the breeding cycle is shortened, and it is also very marketable. However, the use of this early breeding of the deduction of sales, not official our inland waters to grow sales, because the detention of the growth of the accumulated temperature is high, the salinity of the living waters is relatively high, after entering the inland waters of breeding, the growth specifications are small, the survival rate is low.

Large-sized crab species raised in coastal low-salinity waters, this crab species is precocious, even if the environment is good, in practice, it is difficult to raise large-size adult crabs.

Generally, when buying large-scale seedlings, try to be far away from the sea, because the closer to the sea, the higher the salt content of the pond water, and the cultivated buckle crabs are easy to mature early, and it is difficult to raise large-scale adult crabs.

When buying crab seedlings, some breeding friends blindly choose crab seedlings with large specifications, thinking that crab seedlings with large specifications can raise large-sized crabs, but in fact, this idea is one-sided. River crabs are ferocious predators, and male crabs have a stronger predatory ability than female crabs. Blindly selecting crab seedlings with large specifications often has more male crabs and fewer female crabs, resulting in a high bait coefficient and affecting the breeding efficiency.

1. According to the actual current situation, the area for raising crabs should be reasonably and appropriately, focusing on the use of freshwater quality, abundant dissolved oxygen and a large number of aquatic plants, snails and other feed resources. Then select areas with gentle water flow, no industrial pollution, abundant aquatic plants and snail resources, water depth of 1-2 meters, flat lake bottom, and slow water flow.

2. First of all, we should pay attention to the disinfection of the pond. The pond is cleaned as much as possible in winter, first draining the crab fry pond, digging out the silt, repairing the loopholes, removing weeds, and letting the bottom of the pond be frozen and exposed to the sun for a few days, and then irrigated with water and disinfected with medicine.

3. Secondly, we should always check the water quality, change the new water, and remove any leftover food and dirt in time to keep it clean. In addition, more aquatic plants should be added, and the yield of crabs basically depends on the number of aquatic plants in the water body and the number of organisms they can eat, so it is important to plant aquatic plants. You can plant duckweed, water lotus, etc. in the crab pond to increase the dissolved oxygen content of the pond and increase the content of vitamins.

To put crab seedlings in the Mid-Autumn Festival, it is necessary to do the following: 1. Do a good job of preventing dust and combustion. It is easy to escape when the crab fry come ashore and be eaten by rats and birds.

2. Put bait in the middle of the water appropriately, reserve energy, wait for wintering, and also prevent crab seedlings from feeding ashore. 3. Autumn water has become thin after spring and summer consumption, and appropriate fertilizer and water are used to prevent weak photosynthesis and hypoxia in winter. 4. Buy high-quality crab seedlings.

(1) Understand the production process of crab hatchery.

Before purchasing crab seedlings, farmers should first understand the entire production process of crab seedlings, mainly including broodstock, feed use, cultivation cycle, etc. The broodstock used to breed crab fry must be in the national original seed farm or in the large water body of the natural lake, and the male and female crabs should come from different waters to avoid inbreeding. Broodstock Specifications:

Female crabs should not be less than 125 grams, and male crabs should not be less than 150 grams. The quality of crab seedlings cultivated with abundant insects (Artemia) was better, while the quality of crab seedlings cultivated with substitute baits such as freshwater flea and egg yolk was poor. Day Age:

More than 6 days of age. Body color: light turmeric yellow, no variegated seedlings in the group.

Salinity: 4 or less. Specifications:

140,000 160,000 kilograms, the size of the group is the same, and the specifications are neat. Mobility: Crab fry can quickly disperse on their own in the crab hatch box.

Seedling stage water temperature: 20 24, the difference between the water temperature of the nursery pond and the water temperature of the breeding pond is within 2, and the maximum is not more than 4.

2) Drain the pool after disinfection.

1 day before the crab seedlings are out of the pond, it is best to disinfect them with drugs once to kill some pests, reduce the occurrence of diseases during the breeding period, and also eliminate some crab seedlings with poor physique.

3) Pay attention to the method of catching seedlings.

When crab fry are fished, the gas and bait should be stopped, and light trapping should be used, so that the crab seedlings have less impurities and strong vitality. Drain the water before packing, and sprinkle it evenly when entering the box to prevent crab seedlings from sticking to each other and squeezing each other and causing death.

4) Master the shipping time.

The early seedlings should be transported during the day, and the late seedlings should be transported at night.

Before and after the Qingming Festival, the crab seedlings were put in, the size was about 80 heads, the environmental compound river crab grew normally, the full price bait was sufficient, the effective accumulated temperature was more than 2800, the female crab shelled four times, and the male crab shelled five times. The average size of female crabs is two, and the average size of male crabs is 3 taels.