CATDOLL : CATDOLL: What are the key points in the artificial breeding method of swimming crabs?

The swimming crab, also known as the swimming crab, is a famous large edible marine crab. It has strong adaptability to environmental changes and fast growth, making it a suitable species for current breeding.

1. Selection of breeding pond

Earthen ponds are preferred. The structure of the ponds is similar to that of semi-intensive shrimp ponds. Existing shrimp ponds can also be remodeled to culture swimming crabs. The area should be small or medium, with a water depth of 1.5-2 meters. To maintain good water quality, the culture pond should be able to fully change water. Swimming crabs like to live along the edge of the pond. The slope area should be increased as much as possible to avoid excessive density. Swimming crabs have the habit of burrowing in the sand. The bottom of the pond should be laid with 10 cm thick medium-coarse sand and small sand piles to allow them to burrow in the sand. To reduce cannibalism, a hidden place for swimming crabs should be built at the bottom of the pond with stones, tiles, etc.

2. Preparation before planting

Before stocking, drain the pond water, expose the pond bottom to the sun, and remove aquatic animals that eat crab seedlings. You can also use quicklime to clean the pond. If the water depth is less than 10 cm, use 75 kg of quicklime per mu to turn it into lime milk and sprinkle it all over the pond. 7-10 days after cleaning the pond, water can be added to the pond, and a 60-mesh cone net is set at the water inlet for filtration to prevent harmful organisms from entering.

3. Stocking of seedlings

(1) Stocking time: In order to grow commercial crabs (about 250 grams) in the same year, we should focus on "early" and try to use the first batch of swimming crab seedlings. However, it should be noted that the same size of seedlings must be stocked in the same breeding pond to reduce the chance of cannibalism due to uneven sizes and increase the survival rate.

(2) Stocking density: For ponds with clean bottom and good water exchange conditions, the initial stocking density is 2,000-3,000 crabs/mu, and the growth and survival rates are good. Too high or too low density will affect the growth or survival rate. After the Mid-Autumn Festival, if the adult crabs are no longer molting in a small area, they will be put on the market in winter after a short period of fattening. The stocking density is about 10 kg per square meter.

4. Feeding and Management

1. Feeding: Swimming crabs mainly feed on animal baits. For large-scale breeding, it is better to feed low-value shellfish, followed by fresh fish. For young crabs weighing 0.8 grams, the daily food intake is 80% of the body weight, for individuals weighing 30 grams, it is 20% of the body weight, and for individuals weighing more than 50 grams, it is about 10% of the body weight. Those weighing less than 20 grams actively feed day and night, and those weighing more than 20 grams only feed at night. Therefore, in the first 20-30 days of breeding, feed 2-4 times a day, and then feed once every evening, and feed can be thrown along the wall of the pond.

2. Water quality management: The survival rate of a clear pool is low. During the breeding process, the water should be properly fertilized to make the pool water transparent at about 30 cm. In addition, the water should be changed every day. Crabs consume a lot of oxygen during the molting period. If the water is not changed in time, they will die due to lack of oxygen. During the breeding process, the water temperature must be between 17-30℃. If it exceeds 30℃, there is a risk of death. If it is lower than 15℃, it will affect the crab's feeding and even stop feeding. The salinity must be above 20‰. If it is lower than 20‰, there is a risk of death.

3. Separate male and female crabs: The rearing rate of mixed male and female crabs is extremely low, and the price of female crabs in winter is more than 2 times higher than that of male crabs. Therefore, if conditions permit, female and male crabs can be gradually separated during the breeding process. Male crabs can be released from the pond and put on the market at any time after they reach commercial specifications. The ovaries of female crabs can mature regardless of mating or not, and they can be raised until the winter when their ovaries mature and put on the market.