What conditions and methods are needed for farming Chinese mitten crabs?
Chinese mitten crabs are surely a favorite of many people, and this editor also really likes this food, though outside coastal areas these Chinese mitten crabs tend to be a little pricey. As demand for Chinese mitten crabs in the market grows, many people have started to enter this farming industry, believing it has very good market prospects. However, the most important thing in farming is mastering the relevant farming techniques.
How to farm Chinese mitten crabs
1. Preparation for stocking seedlings
Use drawstring nets to block them in and prevent escape. When disinfecting and clearing the pond, remove excess mud, leaving only about 10 cm of mud, and splash quicklime over the whole pond at 200-250 kg per mu, to achieve thorough pond clearing and disinfection, remove debris and wild species, kill pathogens, and improve the substrate. Seven days after treatment, flush with water once to remove filth, then dry the pond for 3-5 days before adding water.
2. Plant aquatic plants well
To farm Chinese mitten crabs, you must first plant aquatic plants well. Aquatic plants are one of the natural baits for Chinese mitten crabs, can play a good role in purifying water quality, and are also a place for Chinese mitten crabs to rest and hide from enemies. Mainly algae. An appropriate amount of river snails can also be added.
3. Reasonable stocking
Before release, disinfect the crab seedlings, separate them evenly by size, and when releasing them use net enclosures within the water area, letting the crabs adapt to the environment for 1 month before removing the net enclosures. Generally, crab seedling stocking should follow the "three suitables" and "one temporary holding" principles. That is, suitable density, suitable timing for stocking, suitable size, and temporary holding first before release.
4. Daily pond patrols
Morning pond patrols are mainly to check whether there is leftover bait, so as to arrange the day's bait well; midday pond patrols are mainly to measure water temperature and observe water color conditions and pond water changes; evening and nighttime pond patrols are mainly to observe the activity and feeding conditions of the river crabs, and take timely measures when problems are found.
What conditions are needed to raise Chinese mitten crabs
Chinese mitten crabs hide away or live in burrows during the day, and come out at night to forage. They like water bodies with clear water quality, sufficient dissolved oxygen, and abundant aquatic plants; they dislike fertilized water and sewage, fear lack of oxygen, and have a very obvious avoidance of poor water quality. They like weak light and fear strong light, like quiet and fear disturbance. When the water temperature reaches above 10°C they begin feeding, around 15°C they molt and grow, and 20-28°C is the peak growth period. Excessively high water temperature inhibits river crab feeding, growth, and molting.
Adult crab farming ponds should strive to meet the above requirements of the river crab's living habits, letting Chinese mitten crabs live in an environment similar to natural conditions. Adult crab farming ponds require the following conditions:
1. Convenient transportation, quiet environment, sheltered from wind and facing the sun.
2. Abundant water source, good water quality, convenient drainage and irrigation.
3. Area generally 5-10 mu is suitable. If the area is too small, water quality is not easy to stabilize; if too large, management is inconvenient.
4. Pond depth 1.5 m, water depth 1-1.2 m.
5. Pond slope 1:3. This can greatly reduce the number of river crabs living in burrows.
6. Pond shape is rectangular, long east-west and narrow north-south, with a length-to-width ratio of 5:3.
7. Soil quality: the pond ridge is relatively wide and the soil is tight; loam soil is best. The pond does not leak, and the mud at the bottom of the pond does not exceed 5 cm.
How to identify inferior Chinese mitten crab seedlings
1. Drug-damaged seedlings
Repeated use of antibiotics such as oxytetracycline during artificial breeding can cause crab seedlings, after molting and metamorphosing into young crabs, to be unable to absorb calcium, so the shell cannot harden, and they often swim to the pond edge and die in large numbers.
2. Molting seedlings
If some of the crab seedlings have already molted and metamorphosed into first-stage young crabs, they cannot be purchased, otherwise after transport the crab seedlings will die in large numbers.
3. Variegated seedlings
Crab seedlings vary in body color from dark to light, and individuals vary in size. With this kind of crab seedling, if they are natural seedlings, they may be mixed with other species of crab seedlings; this situation is common among natural seedlings. If they are artificially bred seedlings, it means the crab seedlings developed unevenly and are very prone to cannibalism during molting.
4. Seawater seedlings
The desalination of the crab seedlings is incomplete and the seedling bodies are deep black. If they are moved directly into freshwater for cultivation, whether natural or artificial seedlings, they will fall unconscious and die.
Advantages of releasing crab seedlings in winter
1. Low price
Every year from mid-October to mid-November is the period when large numbers of crab seedlings are caught, transferred to ponds for concentrated overwintering, and sold. During this period, buying seedlings is inexpensive, generally about 1 yuan each, while in spring crab seedlings sell for 2-3 yuan each.
2. Safe transport
Newly caught crab seedlings store abundant fat in their bodies, are strong in constitution, and have strong adaptability and resistance. In addition, at this time the temperature difference between north and south is only 5°C-10°C, and air humidity is high, making handling easy, management simple, and transport safe and reliable.
3. High survival rate
In winter, because the water quality is clean, bacterial and viral activity weakens, and the chance of the released crab seedlings being infected by various pathogens is reduced; in spring, however, crab seedlings suffer invasion by multiple pathogens that cause disease, lowering the survival rate.
4. Long growth period
Crab seedlings released in spring have a growth period of only more than 6 months; excluding the adaptation period, the growth period is even shorter, so small individuals and low yield are unavoidable. Releasing crab seedlings in winter can generally extend the effective growth period by 1 month to 2 months, with significant effects on increasing size, raising yield, and increasing benefits.
That is all for now on Chinese mitten crab farming techniques, and I hope it is helpful to everyone. The farming prospects for Chinese mitten crabs are currently very good, but the farming industry carries certain risks, so everyone should not blindly follow the trend