New techniques for pond-culture of river snails (field snails): artificially simulating the natural ecological environment
River snails are both a popular health food and a bait for raising carnivorous fish. Due to overfishing, natural resources are declining sharply day by day, and the prospect of developing river snail farming looks promising. In recent years, our town has vigorously promoted artificial imitation-natural pond culture of river snails, that is, creating a good ecological environment in the pond, planting a small amount of aquatic plants for the snails to inhabit and escape the heat, placing some branches and stones for the snails to inhabit in three dimensions at different water layers, and where conditions permit, installing an aerator in the pond. Living in such an environment, river snails generally can reach a yield of 800 kg to 1000 kg per 667 sq m. This is a good path to wealth through farming in rural areas.
I. Infrastructure
1. Pond conditions. The requirements are not high; the area can be large or small, and ordinary fish ponds can all be used to raise snails. High-yield ponds mainly raising river snails require a good water source and good water quality. The pond ridge should be more than 1 m wide, with convenient water inlet and drainage and a barrier net installed to prevent escape. The pond water depth should be maintained at 1 m to 1.5 m. The pond bottom mud should be fairly fertile but not too deep.
2. Pond disinfection. 7 to 10 days before stocking the snails, remove excess silt from the snail-rearing pond, repair and compact the pond ridge, and clear the inlet and drainage channels. Then disinfect the pond, that is, use 75 kg of quicklime per 667 sq m, slake it in water and sprinkle it evenly over the whole pond, or with water present use 100 kg of quicklime per 667 sq m at a water depth of 1 m, slake it in water and splash it evenly over the whole pond.
3. Apply sufficient base fertilizer. Use fermented pig and chicken manure as base fertilizer, at 200 kg to 500 kg per 667 sq m; if the bottom mud is fertile, use less; if the bottom mud is lean, use more.
II. Seedling stocking. Select individuals that are relatively large, whose shell surface is intact and undamaged, that quickly retract their body into the shell when startled, and whose operculum tightly and firmly covers the shell opening, as seed snails. Seed snails can be stocked all at once in full, or in multiple batches; stock 100 kg to 150 kg of seed snails each weighing 10 g per 667 sq m, and additionally stock per 667 sq m 20 to 50 silver carp fingerlings of 20 to 50 g, and 5 to 10 bighead carp fingerlings of 20 to 50 g, to regulate water quality. It is not suitable to stock carnivorous fish such as black carp, common carp, crucian carp and yellow catfish. The stocking time for seed snails is March to May. In addition, if seed snails are widely available at the end of the year in winter, they can also be "stocked in winter" just like fish.
III. Feeding management
1. Feeding bait. The main types of artificial bait are rice bran, wheat bran, rapeseed cake, bean dregs and animal offal, etc. Do not feed when the water temperature is below 15°C; a water temperature of 20 to 28°C is most suitable for river snails to feed and grow, and a large amount of feeding is needed, feeding once every 1 to 2 days in the morning or evening, scattering the bait evenly at a fixed feeding ground.
2. Topdressing fertilizer according to the water. The best water color for snail culture is tea-brown or light green, with a transparency of 20 to 30 cm, and meeting the same @#@233@#@ requirements of high-quality water as "fertile, lively, tender and crisp". Determine whether to apply topdressing fertilizer or how much to apply according to the fertility of the water. The topdressing can be either fermented manure or chemical fertilizer. No matter which type of fertilizer is applied, the method of small amounts applied multiple times must be adopted, so as to avoid excessive application spoiling the water quality. Each time apply 100 kg to 150 kg of manure per 667 sq m, or 1 kg to 2 kg of urea.
3. Regulate water quality. River snails are not strong in tolerating hypoxia, so the dissolved oxygen in the water body should be kept above 4 mg/L. If fish are found gasping at the surface due to hypoxia, or large numbers of river snails crawl to the surface layer of the water, it indicates severe hypoxia in the water body, and the aerator must be turned on promptly or fresh water added, so as to avoid mass death of river snails. Normally, observe the water quality frequently and promptly aerate or add fresh water to regulate it, so as to prevent hypoxia in the water quality.
4. Prevent snails from escaping. River snails often escape from the water inlet and outlet, holes, and the overflow pond ridge, etc. Patrol the pond and inspect frequently, and especially examine carefully during heavy rain.
IV. Disease prevention and control. Apart from poor shell growth due to calcium deficiency and soft operculum, and damage from leech disease, river snails generally have no other diseases. Frequently splashing quicklime into the pond can prevent and control calcium deficiency. If leeches are found, use grass bundles soaked in pig blood to trap them, which has a good effect. For disease prevention, quicklime, bleaching powder, etc. are generally used, and drugs that kill crustaceans such as shrimp and crabs must not be used. In addition, strictly guard against attacks by enemies such as ducks, water birds and water rats.
V. Harvesting for market. When small snails grow to 10 g in weight, they can be harvested for market all at once or in batches. Be careful to avoid the breeding season, harvest the large and leave the small, and keep enough parent snails to continue breeding. You can catch them by draining the pond, or catch them with a large-mesh hand net while the water is present, so as to harvest the large and let the small escape.