High-yield pond culture techniques for freshwater pomfret

The freshwater pomfret, scientifically known as Piaractus brachypomus (short-snouted giant tetra), is an excellent large tropical economic fish with many aquaculture advantages: fast growth, large individual size, omnivorous feeding habits, strong disease resistance, high catch rate, delicious meat and rich nutrition. This species was first introduced to He County in 1998. From 2001 to 2004, our station successfully carried out high-yield pond culture demonstrations of freshwater pomfret for 4 consecutive years at the Gongyi Farm in Liyang Town, maintaining a yield of around 1000 kg per mu, with considerable economic returns.

1. Pond conditions. The farm is located in the northern suburbs, close to a tributary of the Shiba River system, far from factories and residential areas, with abundant water, good water quality, separate inlet and drainage systems, and no pollution sources nearby. The culture pond is rectangular, oriented east-west, with an area of 0.57 hectares, a water depth of 1.5-2 m, a flat bottom, a slope ratio of 1:2.5-3, and is equipped with one 3 kW paddle-wheel aerator.

2. Pond preparation. Every winter, the pond must be drained and sun-dried. Around April 15 of the following year, quicklime is used to clear the pond. For dry clearing, the quicklime dosage is 75 kg per mu; for wet clearing, the quicklime dosage is 150 kg per mu. 10-15 days before stocking fingerlings, adjust the pond water depth to 1.2-1.3 m and install the aerator.

3. Fry and fingerling stocking

1) Stocking time. As a tropical fish, the freshwater pomfret has poor tolerance to low temperatures. Fingerlings can only be stocked when the water temperature remains above 20-22°C. The usual stocking time is mid-May, no later than the end of May. It is best to stock at noon on a sunny day.

2) Source of fry and fingerlings. The stocked fingerlings came from the Tianbang Fisheries Research Institute in Xiangquan Town, He County. The fingerlings bred by this institute using hot spring resources are robust and uniform in size.

3) Stocking quantity and size. Due to the many aquaculture advantages of the freshwater pomfret and the superior pond conditions, we stocked at a rate of 1200 fish per mu. To facilitate early marketing, a stocking size of 12-15 fish/kg is appropriate. Before stocking, soak in a 3-5% sodium chloride solution for 5-8 minutes, and hold in a net cage in the pond for 2-3 hours. In addition, to improve pond water quality, stock 100 silver carp and bighead carp fingerlings at 6-10 fish/kg per mu in a 6:1 ratio.

4. Feed feeding

1) Fixed location. That is, fix the feeding location, which facilitates both the freshwater pomfret's feeding and the staff's inspection of the fish's feeding situation.

2) Fixed quality. That is, do not feed spoiled or moldy feed. The types of feed fed include: wheat, soybean, rice bran, animal carcasses, slaughterhouse offal and special compound feed. For plant-based feed, once mold appears, use should be stopped immediately. For rotten animal feed, reduce feeding frequency and amount. Otherwise, it will affect the quality of the adult fish. In production, we mainly choose wheat, black soybean and special compound feed, ensuring the crude protein content in the feed is ≥25%.

3) Fixed time. Feed 4 times a day, at 9:00, 11:00, 14:00 and 16:00. At 9:00 and 14:00, feed special pellet feed for freshwater pomfret; at 11:00 and 16:00, feed a mixture of wheat and black soybean.

4) Fixed quantity. When feeding, determine the feeding amount according to the growth rate, growing season and weather of the freshwater pomfret. Measure the fish body weight once every 10-15 days, and determine the feeding rate and feeding amount according to the weather and temperature. Generally speaking, during the growth period of the freshwater pomfret, the initial feeding rate is 3-4%, the middle period is 4-6%, and the later period is 7-8%.

5. Daily management

1) Water quality management. To ensure the culture pond water remains clear, usually change 15-20 cm of water about every 15 days. During the high-temperature period in July-August, add at least 10 cm or more of water every 5-10 days.

2) Pond patrol. Its purpose is to observe the fish's feeding situation, activity situation and the pond's water color and water quality conditions, etc. Persist in doing a good job of pond patrol every morning, carefully and meticulously observing the activity of the fish. During hot noon periods and when the weather is stuffy and rainy, patrol the pond even more intensively. Once any abnormal situation occurs, take corresponding measures promptly.

3) Disease prevention and control. As a fish with strong disease resistance, the freshwater pomfret is not easily infected by diseases. During the culture process, emphasis should be placed on the following preventive work.

(1) Prevention of bacterial diseases: apply quicklime at the appropriate time, at a dosage of 15-20 mg/kg, which both improves water quality and prevents the occurrence of bacterial diseases.

(2) Floating head and pond turnover: On sunny days in summer, turn on the aerator at the appropriate time every morning and noon to increase dissolved oxygen in the water body and prevent the occurrence of floating head and pond turnover.

6. Key points of high-yield techniques for freshwater pomfret

First, when stocking, the fingerling size must not be too small, the size should be as uniform as possible, and the difference must not be too great. Moreover, one must not deliberately stock multiple sizes of fingerlings in the same pond for the sake of future partial harvesting and marketing. Second, the freshwater pomfret is an omnivorous bottom-dwelling fish. When it is the main cultured species, other bottom-dwelling fish must not be stocked in the pond, otherwise the yield per mu will be affected. Third, the stocking time for freshwater pomfret is generally mid-May, when the water temperature is stably maintained above 20-22°C. Stocking too early, when the temperature is unstable, easily affects the survival rate; stocking too late affects its growth rate and is not conducive to early marketing. Fourth, the freshwater pomfret has a large appetite and is greedy. When feeding, one must follow the four-fixed method, feeding small amounts multiple times, and must not overfeed. In production, we have observed freshwater pomfret dying from overeating.