Key Technical Points for Nursing Summer-Fingerlings of Freshwater Pompano

Freshwater pompano fry reared for about 20 days, with a body length of about 3 cm, are called summer-fingerling fish. The key nursing techniques at this stage are as follows:

1. Pond selection. The pond should have abundant water sources, good water quality free of pollution, good light, and convenient water intake and drainage, with a length-to-width ratio of 3:2 and a size preferably of 2×667 sq m to 3×5667 sq m, a pond depth of 2 m, and loam as the preferred bottom soil.

2. Pond clearing and preparation. 1. Pond repair: the sluice gates of the pond must be firm; for old ponds, remove excess sludge from the bottom while keeping a 5 cm to 10 cm thick layer of sludge, which helps cultivate food organisms. 2. Pond disinfection: for each 667 sq m of dry pond, use 50 kg to 60 kg of quicklime or 200 ppm quicklime and splash it over the whole pond at noon on a sunny day, then stock fry after 7 to 10 days; or splash 20 ppm bleaching powder over the whole pond and stock fry after 3 to 4 days.

3. Stocking density. Stock 300,000 to 400,000 fry per 667 sq m. To be safe, test fry should be stocked before stocking. Before stocking, control water transparency at 40 cm to 50 cm to prevent large water fleas in the pond from injuring the delicate fry. It is necessary to forecast several days of fine weather, which has a considerable effect on the survival rate of the fry. Choose a sunny morning at 7 to 8 o'clock; first soak the oxygen-filled nylon bag in the water for 30 minutes. When releasing the fry, do so at the upwind area of the pond, first part the water surface, then pull back the corners of the bag so that the fry enter the pond evenly in the water.

4. Feeding technique. Three to 4 hours after stocking, feeding can begin. For every 100,000 fry, feed 6 egg yolks and 250 g of young eel feed daily. The egg yolks must be filtered through a 40-mesh screen. Generally, feed 5 to 6 times a day. Splash the feed evenly along the pond edge, requiring small amounts and many times. After 10 days, switch to feeding soybean milk, and increase the daily feeding amount, adjusting it once every 5 days. In addition, adjust as appropriate according to weather, water temperature, and water quality.

5. Water level control. At first, the water level is 50 cm deep, then add 20 cm to 30 cm of water every 5 to 6 days until it reaches 1.5 m deep.

6. Pond patrol. Patrol the pond once each in the morning, at noon, and in the evening every day. Remove frog eggs and debris promptly, observe the degree of floating head, and use this as a basis for feeding and adding water. At noon on sunny days, run the aerator for 1 to 2 hours; in the evening, observe whether there are signs of fish disease.

7. Seine net exercise. After about 20 days of fry nursing, exercise with a seine net 2 to 3 times before leaving the pond. Choose a sunny morning at 9 to 10 o'clock. The first time the net is drawn together, the movements must be light, quick, and brief; the next 2 to 3 times, appropriately extend the time of drawing the net together, with the procedure based on no fish dying. Its purpose is to strengthen the fish's physique.

8. Fish disease prevention and control. Follow the principles of giving priority to prevention and treating disease early. Ichthyophthirius disease: splash 0.1 ppm to 0.2 ppm mercurous nitrate over the whole pond, preferably 0.13 ppm to 0.15 ppm, or splash formalin at 25 ppm to 30 ppm over the whole pond once a day for 2 consecutive times. Copper sulfate is strictly prohibited for treating this disease. Trichodiniasis: splash 0.7 ppm ferrous sulfate mixture over the whole pond once a day for 2 consecutive times. Ascites disease: splash 1 ppm bleaching powder (effective chlorine content above 25%) over the whole pond, and combine with medicated feeding, mixing 0.3% oxytetracycline into the bait and feeding for 5 to 6 consecutive days. In addition, harmful organisms include water centipedes and dragonfly larvae; splashing 0.5 kg of diesel oil per 667 sq m of water surface over the whole pond to expel them has a good effect.