River crab breeding technology

River crab breeding technology
Adult crabs prefer a water environment with clean water and greater transparency, with overgrown aquatic plants and abundant food. River crabs are most suitable for growth. Currently, most crabs are cultured in ponds, lakes, rivers and rice fields. Therefore, for pond cultivation of river crabs, great efforts must be made to plant aquatic plants. The main types of aquatic plants include duckweed, Azolla, water hyacinth, water lily, Hydrilla verticillata, hornwort, Vallisneria, water peanut, etc. Pay attention to disinfection and damage prevention when transplanting.
6. Daily management
Look at the weather: Feed more when the weather is sunny, feed less on cloudy and rainy days. In hot and muggy weather, you can stop feeding before there is no wind and showers. In foggy days, feed after the fog subsides.
Quantitative: "If a fish does not eat for one day, it will not grow for three days." The same is true for river crabs. This requires determining the feeding amount according to the size, density, different seasons, weather, and activity conditions of the river crabs. Generally, the daily feeding amount is 8-10% of the body weight of the crabs in the pond. A small feeding amount can only maintain life. Exceeding the appropriate time range will also affect growth and increase the feed coefficient.

Pay attention to frequent water changes to keep the water level stable. Change the water once a week in spring and every 3 days in summer. If the high temperature persists, change the water every day. In autumn, the weather is hot and muggy weather often occurs, and the water quality is easy to deteriorate. Pay special attention to water changes. Change the water once every 2 days. The water change accounts for 1/3 of the entire water area.
The water quality is required to be fresh and pollution-free, with convenient water intake and drainage, sufficient water sources, and compliance with national fishery water standards.
After the medicinal properties of the clear pond disappear, the pond water should be kept at 20-30cm. After the water temperature gradually rises, aquatic plants can be planted. For ponds planted with submerged plants such as Hydrilla verticillata and Vallisneria, due to their late germination, it is necessary to set up a water peanut (Hydrophylla philodendron) strip 1 meter away from the edge of the pond, with a width of 2 meters, as an auxiliary measure to absorb water body fertility, regulate water quality, improve river crab habitat, avoid enemy molting sites, and provide shade and cooling.

　　The main types of fertilization include: fermented and sterilized organic fertilizers and inorganic fertilizers such as superphosphate and dicalcium phosphate. The first is to adjust "new", that is, add new water, once every 5-7 days, and change the water once every 10 days and a half. In high-temperature seasons, add 20-30cm of water every day, and change the water once every 3-5 days.
The water depth is controlled at 0.5-0.6cm from March to May, 1.2-1.5m from June to August (the water level may be deepened appropriately in high temperature seasons), and stabilizes at around 1m from September to November. As the stocking density of crab seedlings in our county continues to increase and the breeding output continues to increase, the ecological environment and water quality regulation of crab ponds have been paid more and more attention by the majority of farmers. Practice has proved that in the crab breeding process, the full use of microecological preparations has obvious effects on improving the ecological environment of crab ponds, regulating water quality, improving crab immunity, preventing diseases, and promoting growth. When purchasing, farmers must carefully read the main strains contained on the label, the main mechanism of action after being put into water or mixed with erbium and fed, and use them in a targeted manner.
1. Under natural breeding conditions, there are many factors that will affect the effectiveness of microecological preparations, such as weather, water temperature, water quality, water body fertility, and the type of breeding. The effects vary greatly.
Water peanuts can also induce some live bait to be eaten by river crabs, such as water worms and small fish, shrimps, snails and aquatic insects among annelids.

Second, a "cluster" of vines must be formed in the pond. It should not be a few water pods together, but clusters together, otherwise the above effect will not be achieved.

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