What are the common varieties of shrimp fry and the breeding methods?
Crayfish, as the "king of late-night snacks", has good taste and high nutrition, and the demand for it among people's pursuit of good food is still relatively strong. Although the market for crayfish has fluctuated continuously in recent years, as a traditional aquaculture industry, its popularity has remained high. And in order to achieve breeding goals and increase breeding profits, the management of the shrimp fry cultivation stage is particularly important. So how should shrimp fry be bred? And what are the common varieties? Let's take a look together.
What are the common varieties of shrimp fry?
1. Australian freshwater crayfish fry: This variety is suitable for large-scale farms, and it needs to overwinter in winter.
2. Macau shrimp fry: This variety is suitable in winter for fish and shrimp ponds that are not covered with winter sheds. Brackish water locations are best, and the shrimp are caught and sold on the market around the Spring Festival.
3. Japanese flower shrimp fry: This variety can be stocked in June and July, requires salt water (salinity) of 7 degrees or above, and a siliceous sand bottom. If managed properly, the harvest is still good.
4. Giant river prawn fry: When it is relatively difficult to culture whiteleg shrimp, this variety is a relatively good substitute supplementary variety.
5. Whiteleg shrimp earthen-pond fry: This variety is suitable for earthen pond culture with low requirements, especially for polyculture, because the price of earthen-pond fry is relatively low and the risk is smaller, making it a supporting option for breeding.
6. Red swamp crayfish fry: that is, crayfish. As a new highlight of aquaculture in South China, whether in breeding technology or market consumption, most farmers are believed to be quite familiar with it.
What are the breeding methods?
1. Prepare the pond
Before stocking shrimp fry, the relevant preparation work for the pond must be done well. First, the pond must be cleaned and maintained, preferably by turning over the bottom, and at the same time the pond should be disinfected, cleared of wild organisms, and freed of natural enemies and disease sources. When water is added, it must be thoroughly filtered to prevent natural enemies and competitive organisms from secretly entering the pond. Aquatic plants should be complete; floating plants, submerged plants, and emergent plants are best all taken into account, covering about 60% of the entire pond area, and artificial shelters can also be appropriately added.
2. Fry stocking operations
One or two days before stocking, test again whether the water quality indicators meet the requirements. First is salinity: the salinity at the fry farm is 18 degrees, and the suitable salinity range for shrimp fry is 18 plus or minus 2 degrees; second is temperature: the optimum growth temperature for shrimp fry is 28-32°C; finally is the stocking time, preferably in the morning or evening while ensuring the water temperature is above 25°C, because during this time period the temperature and air pressure are relatively lower and closer to the shrimp fry transport environment.
When shrimp fry leave the farm they are usually at the P4 stage. After nearly 20 hours of transport, stress is bound to occur. One hour before entering the pond, adjust aeration to reduce harm to the shrimp fry, splash VC or polysaccharide anti-stress drugs throughout the pond, and supplement suitable feed in time to reduce the stress response of the shrimp fry and help them recover their strength. Plan the stocking density according to the water volume of the culture pond. The cultivation density of shrimp fry is generally 5,000 to 70,000 tails per cubic meter of water, and the cultivation time and management should be controlled according to individual habits and experience.
3. Fry breeding management
Observe the activity of the shrimp fry 20 min after stocking. If the shrimp fry sink to the bottom or swim against the current, it indicates good vitality. One to two hours after stocking, feed can be given: brine shrimp nauplii or shrimp flakes, with initial feeding amounts of 5 g per 10,000 tails and 1 g per 10,000 tails respectively. Within one week after stocking, water needs to be changed and salinity adjusted. There is relatively great stress, so brine shrimp nauplii need to be supplemented to strengthen physique.
4. Later-stage cultivation
During the cultivation process, change the water once every 7-10 days, each time replacing 1/3 of the pond water, and keep the dissolved oxygen content of the pond water above 5 mg/L; about every 20 days, use 20 g of quicklime per cubic meter of water, dissolve it in water, and splash it over the whole pond once, so as to regulate water quality and increase the content of free calcium in the water, providing the calcium needed by the shrimp fry during molting and growth. After 25-30 days of cultivation and 5-8 growth molts, the shrimp fry can reach a body length of 3 cm.
Overall, the breeding and cultivation of shrimp fry is still relatively simple for experienced farmers, and being able to breed shrimp fry themselves can save a considerable amount of the cost of introducing seed stock. However, to improve the reproduction rate and survival rate of shrimp fry, relying on experience alone is far from enough. Only when all key links are well connected can the smooth progress of fry stocking and shrimp fry cultivation be ensured.
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