Detailed Explanation of Rice-Field Crayfish Farming Techniques and Conditions

Crayfish are currently distributed in many parts of China, and quite a lot of people are farming them now. In addition to the most traditional farming methods, rice-field crayfish farming is also very popular now. However, before using rice fields to farm crayfish, you must master the techniques involved, and you also need to do the preparation work for farming in advance.

Rice-Field Crayfish Farming Techniques

1. Field disinfection: Disinfect the field 15 days before releasing the crayfish. Quicklime can be sprinkled at 750-1125 kg/hectare. After the toxicity has dissipated, water can be added.

2. Fertilizing and cultivating water: 7-10 days before releasing the crayfish, fill the field ditches with water to 60-80 cm, and apply farmyard manure once at 15-30 tonnes/hectare to cultivate feed organisms.

3. Planting aquatic plants: Plant aquatic plants such as Elodea (in winter or early spring after clearing the ditches), Hydrilla verticillata and Vallisneria (in March) in the crayfish-farming ditches and field ditches, so that the aquatic plant coverage rate in the ditches reaches more than 40%, to meet the environmental needs for crayfish growth and development. To provide feed for the crayfish seed, some river snails can be placed in the ditches to let them reproduce naturally.

4. Releasing shrimp fry: For rice-field crayfish farming, it is best to release the fry after rice transplanting in June. At this time the rice field has already been cultivated, which helps the crayfish adapt to the environment, avoids damaging the fry during field cultivation, and increases the survival rate of the crayfish seed. Generally, the stocking size is 250-600 individuals/kg, and the stocking density of juvenile crayfish is 225,000-300,000 individuals/hectare. Before stocking, the shrimp fry and shrimp seed need to be soaked and disinfected in 3% salt water for 3-5 minutes.

5. Water and fertilizer management: After the crayfish are stocked, ditch management is a very important step. Keep the rice-field water depth at about 20 cm. Water is generally added between 10:00 and 11:00, keeping the temperature of the incoming water close to the rice-field water temperature. During rice-field management, the water level should also be regulated according to the requirements for draining the field and pest control. Drain the field appropriately in the middle stage of rice growth, thereby increasing light exposure, boosting root vitality, killing bacteria and raising temperature. At ordinary times, flood control, drainage and anti-escape work must also be done well. After heavy rain, promptly check whether the water inlet and outlet and the crayfish-blocking facilities are intact to prevent crayfish from escaping.

Crayfish Farming Conditions

1. Create a good growth environment for crayfish. Crayfish are crustaceans. They have a pair of particularly well-developed claws and have the habit of digging burrows to live in, generally burrowing near the water's edge close to the bank. Crayfish prefer shade and fear light. When the light is weak or dark, they crawl out of their burrows; when the light is strong, they sink to the bottom or hide in their burrows. According to the habits of crayfish, a 50 cm high anti-escape net can be added along the edges of rivers and ponds to prevent crayfish from escaping. At the same time, the ponds should simulate the ecological environment of crayfish under natural conditions, with 10-15% aquatic plants and hiding objects planted in the shallow areas along the pond edge, creating an environment for crayfish to inhabit and molt, and reducing mutual killing.

2. The impact of water quality on crayfish yield should not be ignored either. Water quality directly affects the healthy growth and development of crayfish. During farming, keep the pond water pH between 7.5-8.5 and the transparency at 30-40 cm. New water should be added frequently, and quicklime solution should be sprinkled regularly to regulate water quality and prevent disease and incomplete molting.

Feeding and Management of Crayfish

For rice-field crayfish farming, try to feed at fixed times, fixed locations, fixed amounts and with fixed quality. Crayfish are omnivorous and eat all of the following: meat-based feed (small trash fish, snail meat, river meat, fish meat, earthworms, animal offal, silkworm pupae), concentrated feed (sugar cake, corn, wheat, barley flour) and green feed (various aquatic grasses, vegetable trimmings, etc.). The daily feeding amount is generally 4-6% of the crayfish body weight. In the early stage, feed twice a day, once in the morning and once in the afternoon. In the later stage, feed once at around 18:00.

What to Do About Ciliatosis in Crayfish

Ciliatosis is caused by the attachment of ciliates and appears as a thick layer of “fur” formed on the body surface, appendages, gills and other parts of adult crayfish, juvenile crayfish, larvae and fertilized eggs.

Prevention and treatment methods:

1. Sprinkle 0.3-0.5 mg/L tetraalkyl quaternary ammonium salt complex iodine over the whole field.

2. Use Xianchongjing or zinc sulfate according to the instructions. In addition, feeding special artificial feed for Procambarus clarkii molting can promote molting in Procambarus clarkii, causing it to shed the old shell covered with ciliates.

For rice-field crayfish farming, first do a good job of site selection, then carry out disinfection, and then release the shrimp fry. In the later stage of farming, feeding work also needs to be strengthened. Timely disease prevention and control is also a key factor in ensuring their growth. Only by doing these things well can the crayfish grow very well.