Inland young crab high-yielding cultivation techniques
2025-07-11 11:06:01
In the middle and lower reaches of the Yangtze River, particularly in the inland areas of Anhui and Jiangsu, many farmers have mastered the technique of raising around 200 kilograms of juvenile crabs from bigeye larvae. However, the yield per mu varies significantly, and the output per 500 grams of bigeye larvae is also inconsistent. Over three years of cultivation, the author has managed to stabilize the yield at approximately 100 kg per mu, with about 75 kg of juvenile crabs produced from 500 grams of bigeye larvae. Below are the key techniques that have contributed to this success.
1. **Selecting the Pond**: The ideal pond size is around 3 mu. It's recommended to build the crab pond while using a nylon gauze net to protect the slopes. This helps prevent damage to the pond during the second year and ensures consistent growth of the seedlings. A 1-meter-high dense net should be placed around the pond to keep out frogs and other predators. If multiple ponds are used for continuous breeding, scarecrows can be installed to deter birds.
2. **Pond Clearing**: For newly dug ponds, 30 cm of water should be added per acre, followed by 30 kg of calcified water. For previously used ponds, after selling the seedlings, refill the pond with 1 meter of water and apply 35–50 kg of bleaching powder. After a week, detoxify the water to remove residual chlorine, as it can negatively impact the young crabs. If pyrethroids were used, avoid discharging the water and reapply 30–50 kg of calcified water 15 days later. Use quicklime and a water detoxifier 7–15 days after clearing to eliminate any remaining toxins, which is essential for high yield and good quality.
3. **Planting Aquatic Vegetation**: After clearing the pond, plant aquatic plants such as submerged elodea, borage grass, black leaf algae, water peanuts, water lettuce, and duckweed. Submerged plants should cover more than 70% of the pond bottom, while floating plants should occupy over 50% of the surface area. These plants provide shelter and improve water quality.
4. **Feeding Bigeye Larvae**: Earthworm-based bigeye larvae are introduced in sync with the weather. Based on experience, it’s best to release the larvae between May 20 and June 20, preferably after June. Place 750–1250 grams of larvae per mu. Ensure clear weather for three consecutive days before releasing. In rainy conditions, add oxygen pellets to the water—200 grams per mu in the evening. If the water becomes turbid after rain, use a water clarifier once the rain stops. Two days before introducing the larvae, feed them with soy milk (500 grams per mu daily at 30 cm depth). Upon arrival, briefly soak the larvae in a solution to reduce stress during their first molt. After 8 PM each night, add 200 grams of oxygen per acre to support survival during metamorphosis.
5. **Breeding Management**
(1) **Water Quality Control**: Monitor dissolved oxygen levels when the bigeye larvae are introduced. After metamorphosis, gradually increase the water depth to 80–100 cm. Change the water slowly, no more than 10 cm per day, and do so in the evening. Use biological agents like EM water and ecological treasures to maintain clean, healthy water. Crabs raised this way tend to be strong, with green shells and no signs of ciliates or algae.
(2) **Feeding Strategy**: Fertilize the water to cultivate natural bait. After the larvae arrive, mix 500 grams of soybean milk and 500 grams of cooked fish gills with the larvae and feed them after they metamorphose. Feed them with No. 1 starter feed at 2–3 times their weight, divided into three meals a day. Once they reach the third stage, introduce No. 2 compound feed. After one month, switch to cooked or germinated wheat, feeding twice daily. Avoid leaving leftover food. Adjust feeding based on weather conditions. Long-term use of Luyuan hydrolyzate mix improves growth and survival rates, leading to faster development and better results.
6. **Harvesting and Selling**: By late October, gather water peanuts into piles of at least 20 kg per pile, ensuring at least 30 piles per mu. When customers request seedlings, use a net to collect them from the water peanut piles without harming the crabs. Before selling, perform a simple treatment to ensure the crabs are disease-free, with no issues like limb rot, shell rot, or water mold.
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