Detailed Explanation of Key Techniques for Polyculture of Red Swamp Crayfish in Fish Ponds

Procambarus clarkii, also known as red swamp crayfish, has strong adaptability, grows rapidly, has delicious meat, and is rich in nutrients. Market demand is strong, and it is highly favored by farmers and consumers. In production practice, Procambarus clarkii is mostly polycultured, such as in adult fish ponds, fingerling ponds, and river crab and oriental river prawn culture ponds, etc. The following issues should be noted when polyculturing Procambarus clarkii in ponds.

1. The pond should have convenient water inlet and drainage, be able to maintain a water depth of 1--1.5 m, have a pond slope ratio of 1:3, and be equipped with anti-escape facilities around the pond.

2. It is advisable to use pond-clearing drugs that are harmless to crayfish to clear the pond, and thoroughly kill harmful organisms such as snakehead, catfish, water snakes, and frogs, as well as pathogenic bacteria and parasites.

3. Maintain a certain amount of aquatic plants, branches, and other hiding places in the pond for crayfish to inhabit, climb, molt, and feed. Some aquatic plants can be planted, such as hornwort, alligator weed, tape grass, and water hyacinth. The area covered by plants should preferably account for 1/5--1/3 of the pond water surface.

4. Carnivorous fish must not be cultured in the polyculture pond, and grass carp and bream, which feed on aquatic plants, should also not be stocked in excessive numbers. Species that can be polycultured include silver carp, bighead carp, allogynogenetic crucian carp, river crab, and oriental river prawn. Suitable polyculture species can be selected according to local conditions.

5. Captured wild juvenile shrimp can be selected as seed shrimp, with a size of more than 3 cm, intact limbs, and strong mobility. It is advisable to stock 0.6--10,000 shrimp per mu. Egg-bearing shrimp can also be selected for pond breeding and culture.

6. The amount of bait should be sufficient. When hungry, crayfish may cannibalize each other and may also feed on molting river crabs, oriental river prawns, and juvenile fish. Therefore, bait must be sufficient to meet the feeding needs of crayfish.

7. The bait should be palatable. Powdered bait must not be directly scattered into the pond, which would make it difficult for fish and shrimp to feed, causing both waste of bait and pollution of water quality.

8. The pond water quality should be kept fertile, lively, tender, and fresh, with water transparency of about 30 cm, pH 7--8.5, and dissolved oxygen above 4 mg/L.

9. Use quicklime to regulate water quality and increase calcium in the water body, which is beneficial to crayfish molting and growth. During the peak growth season of fish and shrimp, apply once every 15--20 days, using 10--15 kg of quicklime per mu each time, slaked into lime slurry and spread evenly over the whole pond.

10. When preventing and treating fish and shrimp diseases and insect pests, fishery drugs harmful to crayfish must not be used, especially when selecting insecticides.

11. After 30--40 days of stocking shrimp seed, harvesting can begin for adult shrimp reaching a size of more than 8 cm. Use ground cages and other net-cage fishing gear, which are harmless to both fish and shrimp, harvesting the large and leaving the small for balanced marketing. When conditions permit, shrimp seed can be restocked according to pond conditions, implementing rotational harvesting and stocking.