Ditch Design and Farming Techniques for Raising Crayfish in Paddy Fields

Have you ever heard of raising crayfish in paddy fields? When this farming method is mentioned, many people may find it hard to believe. In the past, paddy fields were generally used only for growing rice, but with the development of the times, more and more farmers are learning to use resources comprehensively, so that they can raise crayfish while growing rice. Come and learn about it with us.

Ditch Design for Raising Crayfish in Paddy Fields

1. Paddy field selection

Choose low-lying paddy fields with sufficient water sources, strong soil water and fertilizer retention capacity, no risk of drought or flood damage, no surrounding pollution, good water quality, convenient drainage and irrigation, and plenty of sunlight for integrated farming. The paddy field area should follow the principle of being convenient for management and feeding, and generally 40-50 mu as one farming unit is suitable. For the first attempt, it is recommended to use paddy fields with existing ditch systems available for use, to reduce the cost of crayfish farming construction.

Facility renovation

2. Digging crayfish ditches

Dig 1 ring ditch within one farming unit. The ring ditch should be dug 1.5-2 m from the field ridge, with a ditch width of 2-3 m and a ditch depth of 1-1.5 m, an outer field ridge top width of about 2 m, and a slope ratio of 1:2.5. To facilitate shallow irrigation of the paddy field, field drying, application of chemical fertilizers and pesticides, and harvesting, crayfish ditches and crayfish pits must be dug in crayfish-farming paddy fields.

The crayfish ditches in the field can be dug after transplanting rice seedlings, and the way they are dug should depend on the shape of the field, the size of the area, and the direction of the drainage outlet. If the paddy field is relatively small, it can be dug in a “field” shape; if the field is long and large, it can be dug in an inner “well” shape or an inner “field” shape, with a ditch width of 0.5-1.0 m and a ditch depth of 0.3-0.4 m being suitable. Crayfish pits can be dug at the intersections of crayfish ditches or at the four corners of the field, connected with the crayfish ditches. Crayfish pits are generally suitable at 1.0 m square and 0.8-1.0 m deep.

3. Reinforcing the field ridges

The soil dug from the ring ditch can be piled on the outer perimeter to build field ridges, which should be tamped, raised, widened, and reinforced to ensure that the field ridges are 0.6-0.8 m higher than the field surface, with a top width of about 2 m. Melons, beans, gourds, and other crops can be planted on the field ridges. After the vines climb onto the trellis, they provide shade and relief from the heat in the hot summer. When digging crayfish ditches, small ridges can be left in the field to provide crayfish with enough places to dig burrows.

4. Setting up escape-prevention facilities

For raising crayfish in paddy fields, the inlet and outlet should be well built. Their locations should be chosen on the soil ridges at two opposite corners of the paddy field, so as to facilitate smooth water intake and drainage of the entire paddy field during farming. Install wire mesh or double-layer fine mesh (about 20 mesh) at the inlet and outlet, and set up fencing on the field ridges with a height of 40-50 cm. Hard calcium-plastic boards or nylon mesh sheets together with hard plastic film, or asbestos tiles, can be used as fencing materials. The corners of the field should be set in an arc shape to avoid crayfish escape and to control the entry of adult crayfish natural enemies.

Crayfish Farming Techniques in Paddy Fields

1. Choose good field plots and dig good crayfish ditches

Paddy fields for farming oriental river prawns require fresh water quality and a stable water level. For this reason, choose field plots close to water sources, with relatively convenient irrigation and drainage, and good soil quality. After plowing and leveling, a crayfish ditch 2 m wide and 1 m deep can be dug at one end of the field, or crayfish ditches 1 m wide and 0.8 m deep in a field shape can be dug around the field and in the middle of the field. Build the irrigation and drainage system, fill with water, and strictly prevent wild miscellaneous fish from mixing in.

2. Release seeds at the right time to increase the survival rate

Start releasing young prawns one week after the rice seedlings are transplanted. Usually, young prawns artificially bred in the same year are used for stocking, with a size of 2000-5000 prawns/kg, and 10,000-15,000 prawns can be released per mu. Choose cloudy and rainy days or sunny mornings for release, and release them at separate points so that young prawns are distributed throughout the water area, avoiding excessive concentration of young prawns and death caused by lack of oxygen. When releasing, movements should be quick to improve the survival rate of young prawn stocking.

3. Scientific bait feeding and strengthened management

After young prawns are stocked, start feeding immediately. Generally, wheat bran, soybean cake, or pellet feed for fish (prawns) can be used for feeding, and some animal-based bait such as snails, shellfish meat, and fish meat should also be appropriately fed. Feed 2 times a day, mainly in the evening, and the daily feeding amount can be controlled at 2%-4% of the body weight of the prawns in the field. Adjust reasonably according to the season, weather, and feeding conditions of oriental river prawns, so that the prawns eat enough and eat well, and promote growth.

Techniques for Selecting Parent Crayfish

Parent crayfish refer to sexually mature male and female crayfish used for breeding crayfish fry. The quality of parent crayfish directly affects the quality of crayfish fry, so the selection of parent crayfish is especially important. Here we will briefly understand the techniques for selecting parent crayfish. Parent crayfish can be selected in September-October of the previous year or March-April of the current year, requiring a body weight of 30-50 g, complete appendages, health without disease, strong activity, and a male-to-female ratio of 2-3:1.

Crayfish Feed Formulas

I. Young crayfish

1. Formula 1: wheat bran 37%, fish meal 35%, peanut cake 25%, clam shell powder 3%. The protein content of this formula is about 45%.

2. Formula 2: fish meal 60%, wheat bran 22%, peanut cake 15%, minerals 3% and trace elements. The crude protein content of this formula is about 50%.

II. Adult crayfish

1. Formula 1: wheat bran 50%, silkworm pupae 30%, soybean cake 10%, rice bran 5%, peanut cake 5%.

2. Formula 2: wheat bran 30%, rice bran 22.5%, fish meal 20%, peanut cake 20%, silkworm pupae 7.5%.

The paddy field crayfish farming model refers to reasonably stocking a certain number of crayfish in paddy fields through certain modifications. In this way, the goal of one field with two industries and multiple harvests in one season can be achieved, and it will also bring relatively considerable economic benefits to farmers.