Key Technical Points for Monoculture of Giant Freshwater Prawn (Macrobrachium rosenbergii) in Ponds
Techniques for Monoculture of Giant Freshwater Prawn in Ponds
Pond Clearing and Disinfection Newly built prawn ponds or ponds converted from fish ponds must be thoroughly disinfected with chemicals before stocking. The commonly used pond-clearing and disinfecting agents mainly include quicklime, bleaching powder, and tea seed cake. Pond clearing and disinfection are generally carried out 1 month before prawn fry stocking. There are two methods: dry pond clearing and disinfection, and pond clearing and disinfection with water. For dry pond clearing and disinfection, use 65-75 kg of quicklime or 5 kg of bleaching powder per mu. For pond clearing and disinfection with water, use 125-150 kg of quicklime per mu (at a water depth of 1 m) or 30-50 g of bleaching powder per cubic meter of water.
Water Filling and Fertilization After the prawn pond has been cleared and disinfected, fill with water and apply fertilizer 7 days before stocking fry. First fill the pond with water 20-30 cm deep, and apply 200-300 kg of fermented organic fertilizer per mu. After several days of sun exposure, raise the water level to 50-60 cm.
Fry Stocking Stock 15,000-20,000 desalinated prawn fry (0.7-1 cm) per mu, or 8,000-12,000 large-size fry (2-3 cm) per mu. After about 150 days of culture, the yield per mu can reach 100-150 kg. Where water quality conditions are good and culture techniques are relatively advanced, the stocking density can be more than 30,000 fry per mu (0.7-1 cm desalinated fry). Note the following when stocking prawn fry: the salinity of desalinated fry should be below 0.3%; the water temperature difference at stocking should be less than 2°C; stock the fry on the windward side.
Feed Feeding In the early stage of giant freshwater prawn culture, animal-based feed is mainly used. If there is plenty of plankton feed in the pond water, newly stocked giant freshwater prawn fry may not need feeding for 1 week; if the pond water is relatively clear and there is little biological feed, feed 4 times a day. After 15 days, feed 3-4 times a day. In the middle and late stages, feed 2-3 times a day, with the evening feeding accounting for one-half to two-thirds of the total daily feed. The feed is best processed into balls and fed at multiple points. In the early stage after fry stocking, feed around the pond at a water depth of about 0.3 m; as the prawns grow, gradually feed in deeper water, but the water depth must not exceed 0.7 m.
The daily feeding amount can be seen in the table below, and is generally adjusted once every half month. In actual production, it should be flexibly controlled according to seasonal and weather changes as well as the feeding and activity of the prawns.
Daily Management Key management points for each stage: (1) Early culture stage. First, propagate feed organisms; second, feed in a timely manner. After the fry are stocked, especially when 0.7-1 cm desalinated fry are stocked, their foraging ability is low, so appropriately increase the feeding amount and promptly feed high-quality palatable feed; third, since the water level is relatively shallow in the early stage, prevent the pond water from becoming too fertile and promptly add fresh water; fourth, pay attention to water temperature. Especially for temporary rearing of early fry, because the air temperature is low, water temperature control must be particularly strengthened to avoid drastic temperature changes caused by stocking, water exchange, cold air, and other factors, which can lead to the death of the fry. (2) Middle culture stage (July-August). The water temperature is relatively high in this period, and it is a season when prawn diseases occur easily. Attention should be paid to water quality regulation, disease prevention, and feeding work, avoiding feed spoilage, excessive feeding, and the appearance of floating head. Regularly splash quicklime and feed medicated bait; ponds with aeration equipment should make full use of the equipment for aeration. (3) Late culture stage. During this period, the prawns grow relatively fast, are large in size, and their food intake increases greatly, so the feeding amount should be increased in a timely manner; pay attention to whether the giant freshwater prawns in the pond show floating head; harvest the prawns at the appropriate time.
Water Filling and Fertilization After the prawn pond has been cleared and disinfected, fill with water and apply fertilizer 7 days before stocking fry. First fill the pond with water 20-30 cm deep, and apply 200-300 kg of fermented organic fertilizer per mu. After several days of sun exposure, raise the water level to 50-60 cm.
Fry Stocking Stock 15,000-20,000 desalinated prawn fry (0.7-1 cm) per mu, or 8,000-12,000 large-size fry (2-3 cm) per mu. After about 150 days of culture, the yield per mu can reach 100-150 kg. Where water quality conditions are good and culture techniques are relatively advanced, the stocking density can be more than 30,000 fry per mu (0.7-1 cm desalinated fry). Note the following when stocking prawn fry: the salinity of desalinated fry should be below 0.3%; the water temperature difference at stocking should be less than 2°C; stock the fry on the windward side.
Feed Feeding In the early stage of giant freshwater prawn culture, animal-based feed is mainly used. If there is plenty of plankton feed in the pond water, newly stocked giant freshwater prawn fry may not need feeding for 1 week; if the pond water is relatively clear and there is little biological feed, feed 4 times a day. After 15 days, feed 3-4 times a day. In the middle and late stages, feed 2-3 times a day, with the evening feeding accounting for one-half to two-thirds of the total daily feed. The feed is best processed into balls and fed at multiple points. In the early stage after fry stocking, feed around the pond at a water depth of about 0.3 m; as the prawns grow, gradually feed in deeper water, but the water depth must not exceed 0.7 m.
The daily feeding amount can be seen in the table below, and is generally adjusted once every half month. In actual production, it should be flexibly controlled according to seasonal and weather changes as well as the feeding and activity of the prawns.
Daily Management Key management points for each stage: (1) Early culture stage. First, propagate feed organisms; second, feed in a timely manner. After the fry are stocked, especially when 0.7-1 cm desalinated fry are stocked, their foraging ability is low, so appropriately increase the feeding amount and promptly feed high-quality palatable feed; third, since the water level is relatively shallow in the early stage, prevent the pond water from becoming too fertile and promptly add fresh water; fourth, pay attention to water temperature. Especially for temporary rearing of early fry, because the air temperature is low, water temperature control must be particularly strengthened to avoid drastic temperature changes caused by stocking, water exchange, cold air, and other factors, which can lead to the death of the fry. (2) Middle culture stage (July-August). The water temperature is relatively high in this period, and it is a season when prawn diseases occur easily. Attention should be paid to water quality regulation, disease prevention, and feeding work, avoiding feed spoilage, excessive feeding, and the appearance of floating head. Regularly splash quicklime and feed medicated bait; ponds with aeration equipment should make full use of the equipment for aeration. (3) Late culture stage. During this period, the prawns grow relatively fast, are large in size, and their food intake increases greatly, so the feeding amount should be increased in a timely manner; pay attention to whether the giant freshwater prawns in the pond show floating head; harvest the prawns at the appropriate time.