What are the methods for raising river crabs in rice paddies and ponds?

At present, the farming area for river crabs in China is expanding year by year, and the peak period for river crabs coming to market is around the Spring Festival each year. So for beginners just entering the industry, how do you raise river crabs in rice paddies and ponds?

Currently, river crab farming mainly consists of two major schools: rice paddy farming and pond farming. Below, let us look separately at the key technical points of each.

I. Raising river crabs in rice paddies

1. Selection of the rice paddy

If you want to raise river crabs in a rice paddy, then the paddy environment must be strictly controlled.

Generally speaking, a rice paddy used for raising river crabs needs to meet the following: a quiet environment, good irrigation and drainage capacity, high water and fertilizer retention, and soil that tends toward clay and loam.

After these conditions are met, the rice paddy must be modified.

A ring ditch, farming pond, field ditch, and water inlet channel need to be dug separately in the rice paddy, and anti-escape equipment must be set up around the paddy; calcium plastic boards and asbestos tiles are relatively recommended.

2. Releasing crab fry

The first thing to pay attention to is the release time for the crab fry. It should be chosen within the period from early May to early June, when the temperature is not very high, which is favorable for the survival of river crab fry.

The release amount of crab fry can refer to about 1 kg per mu. First put the crab fry in the ring ditch and enclose them. After the rice seedlings are transplanted and survive, the enclosure can be removed to let them move freely in the rice paddy.

3. Feeding management

After releasing the crab fry, feeding can begin. Young seedlings can be fed egg yolk once every 3 hours. After they grow to the next size grade, they can be fed wheat bran and soybean cake, about 5 feedings per day.

II. Raising river crabs in ponds

1. Pond requirements

If river crabs are raised in ponds, then the pond specifications must be well controlled. Generally, a pond of about 4 mu is suitable; the pond depth should not exceed 1.5 m and should not be less than 1 m, and the water depth should be maintained at about 0.8 m. As with raising crayfish, the pond bottom should slope 3-5° toward the outlet, and too much silt should not accumulate at the bottom, so it needs to be cleaned regularly.

2. Planting aquatic plants

Before releasing crab fry, a certain proportion of aquatic plants must be planted in the pond. The best aquatic plant varieties are Elodea, tape grass, alligator weed, and so on.

Note that too many aquatic plants or too single a variety must not be planted, as this can easily lead to insufficient nutrient supply in the water body, causing the aquatic plants to rot and breed pathogens.

3. Releasing crab fry

If raising in ponds, you can release either crab fry or crab juveniles. The release amount of crab fry is suitably 1 kg per mu, and crab juveniles are released at 25,000 per mu.

For feed, you can refer to animal-based feed, bran, wheat flakes, aquatic plants, and so on.

In short, whether raising river crabs in open fields or in ponds, you must keep good daily records of river crab growth observations in order to grasp the growth situation in time. Only in this way can you have enough understanding of the river crabs you raise and respond promptly when special situations arise.