CATDOLL : CATDOLL: How to temporarily raise swimming crabs

1. How to temporarily raise swimming crabs

Methods for temporarily raising swimming crabs for 3 or 4 days: change the seawater every day (same salinity and temperature), aerate and aerate for 24 hours, maintain a relatively low temperature (15-20 degrees), and feed small fish and shrimp in appropriate amounts.

Swimming crabs, commonly known as swimming crabs and white crabs, belong to the class Crustacea, the order Decapoda, and the family Portunidae. They live in soft mud, sandy mud, rocks, or water plants near the shore at a depth of 7 to 100 meters. A small number of smaller or medium-sized individuals can also be collected on the low tide line of the intertidal zone. They often use the fingertips of the first three pairs of walking legs to crawl slowly on the seabed, swim with swimming legs, or move forward to the side or back. When encountering an enemy, they raise their large claws upwards to defend themselves or attack the opponent, or use the last two sections of their swimming legs to dig sand and dive into the bottom with their bodies upright. They have the habit of going out at night to forage, have obvious phototropism, and can be trapped with lights.

2. Temporary culture technology of swimming crabs in the Yellow Sea

The most important thing is to ensure that the bottom is clean and pollution-free. The water temperature must not drop. Observe how the dead crabs died and see if there are brown and slightly sunken spots on the abdomen and legs. Finally, it will become a hole. You must pay attention to the bacterial infection of shell ulcers. If you find it, don't rush to use antibiotics, otherwise the bacteria will develop drug resistance. You should kill the bacteria first. The mortality rate of this disease is not covered. It can really reach 50 to 80%. Because I just witnessed it today, and this is a common disease of crabs in winter. Anyway, crabs should not be injured. It has no effect on Jiankang crabs.

3. How to improve the survival rate of swimming crab seedlings at the critical moment of swimming crab breeding?

During the critical breeding season of swimming crab parents, some farmers have recently found that the mortality rate of the purchased sea-caught swimming crab parents during pond cultivation is higher than in previous years. Based on many years of experience in seawater pond farming, the author recommends that farmers strengthen management in the following three aspects to improve the survival and marketability of the parents.

1. Strengthen training

In winter, pond-cultivated swimming crabs are selected as parents for intensive cultivation, which can not only ensure the quality of the parents, but also be unaffected by the market and sea conditions. A small shed is built as a cultivation pond. The bottom of the scattered sail pond should be covered with a layer of sand about 375px, and equipped with oxygenation equipment and heating equipment. After the parent crabs enter the pond, fresh bait is fed and the water is changed in time. When the water temperature drops to 10℃, the swimming crabs will hibernate in the sand. At this time, no feeding is done to reduce the amount of water change. After entering the spring, the heating and ripening time is determined according to production needs. The temperature is increased by 0.5℃ every day, and the temperature is raised to a constant temperature of 18℃, and the parent crabs are waiting for the eggs. The parent crab cultivation density is 3 to 5 per square meter, the water depth is 80 to 2500px, and a small amount of hail is charged. The bait is mainly fresh shellfish, wild fish and sandworms, and the daily feeding amount is 10% of the parent crab's body weight. Change the water once a day, and remove the residual bait, feces and dead crabs in time when changing the water.

2. Prevent injuries

When catching swimming crabs in the sea or in ponds, the movements should be light and fast, and the claws should be tied with thin rubber bands to prevent them from killing each other. For short-distance transportation, they can be covered with wet straw and placed in an insulated box for transportation. For long-distance transportation, live water trucks can be used for oxygenated transportation. If the temperature is high, ice cubes can be added to cool it down appropriately.

3. Pay attention to disease prevention

Before entering the pond, the pond must be thoroughly cleaned and disinfected, and the parent crabs should be bathed in medicine to kill parasites and bacterial pathogens on the body surface. Substances such as allicin and immune polysaccharides should be mixed into the bait to improve the body's disease resistance. During the breeding process, pond patrols should be strengthened to observe the activity in a timely manner. Once a disease is found, treatment measures should be taken immediately.

The above are some methods, and you can take some measures based on these methods.

1. Strengthening cultivation Selecting swimming crabs cultivated in ponds as parents for strengthening cultivation in winter can not only ensure the quality of the parents, but also be unaffected by the market and sea conditions. Build a small shed as a cultivation pond. The bottom of the pond should be covered with a layer of sand about 375px, and equipped with oxygenation equipment and heating equipment. After the parent crabs enter the pond, feed them with fresh bait and change the water in time. 2. Prevent injuries Whether catching swimming crabs in the sea or in the pond, the movements should be light and fast, and the claws should be tied with thin rubber bands to prevent mutual killing. For short-distance transportation, they can be covered with wet straw and wrapped in a heat preservation box for transportation.

Strengthening training

In winter, the swimming crabs are selected from ponds for intensive breeding, which can ensure the quality of the parents and will not be affected by the market and sea conditions. A small shed is built as a breeding pond. The bottom of the pond should be covered with a layer of sand of 375px, and equipped with oxygen and heating equipment. After the parent crabs enter the pond, they are fed with fresh bait and the water is changed in time. When the water temperature drops to 10℃, the swimming crabs will hibernate in the sand. At this time, no feeding is done to reduce the amount of water change.

As far as swimming crab farming is concerned, sand-bottom ponds are better than mud-bottom ponds. This is also true for temporary farming in autumn and winter. The survival rate of sand-bottom ponds is significantly higher than that of mud-bottom ponds. The reason is that the ammonia nitrogen and hydrogen sulfide content in the bottom of mud-bottom ponds is relatively high, and the environment is poor. For ponds with a large proportion of soft mud, it is best to clean the bottom of the pond before the start of farming every year, remove the surface silt, and carry out sand laying transformation. If the bottom has deteriorated, pay attention to reasonable feeding, avoid residual bait, and sprinkle 20g/m³ of quicklime on the whole pond every half month to improve water quality, or use microbial preparations for treatment.

4. How to preserve live crabs so that they can live longer

Put the crabs you bought in a plastic net bag (not a plastic bag) and put them directly in the refrigerator. Never put them together with water. Such crabs can be kept at home for at least 3-4 days and the crabs are still very energetic.

5. What methods are used to treat hair growth on crabs during temporary breeding?

At this time, the hair growing on the crab's body is a ciliate disease, which can be killed with zinc sulfate or special ciliate-killing drugs.

6. I bought too many crabs. Is there any way to make them live longer?

How to preserve hairy crabs

Use plastic buckets/basins to store Yangcheng Lake hairy crabs. Choose vigorous Yangcheng Lake hairy crabs and prepare a 30-50 cm high plastic bucket/basin with a smooth inner wall that is not easy to escape. Put the Yangcheng Lake hairy crabs in it - do not stack them;

Then add water to half the height of the crab's body - mainly to keep it moist, do not bury the crab completely. Because people usually do not have oxygenation equipment, if the water is too deep, the crab will suffocate and die due to lack of oxygen. The bucket/basin does not need to be covered, check the crabs every day, and eat the crabs that are not energetic enough in time. If this method is used to preserve Yangcheng Lake hairy crabs, the crabs can be preserved for more than 5 days when the temperature is not high.