Practical Techniques for Farming Red Drum (Sciaenops ocellatus)

Sciaenops ocellatus, commonly known as the red drum, is also called "red catfish" or "yidianchun" by the locals of Pingtan. It is native to the coastal waters of the South Atlantic and the Gulf of Mexico. Its flesh is tender and delicious, it has strong disease resistance, grows rapidly, and accepts a wide range of feed. In Pingtan County it is gradually becoming a new and popular aquaculture industry. Its practical farming techniques are introduced as follows:

1 Life habits

Sciaenops ocellatus belongs to the order Perciformes, family Sciaenidae, genus Sciaenops. It is a marine economic fish that is eurythermal and euryhaline, warm-water, and anadromous. The suitable temperature range for growth of this fish is 8-35°C, with the optimum at 22-35°C; the suitable salinity range is 0‰-40‰, with the optimum at 20‰-35‰; the pH is 6-9, with the optimum pH 7-8; dissolved oxygen above 3.0 mg/l, with the optimum at 5.0-9.0 mg/l. Because the calcium needed for the growth of Sciaenops ocellatus is mainly obtained through the osmosis of calcium ions (calcium ions) from the surrounding water, it has certain requirements for the total hardness and total oxygen content of the growing area: the calcium ion concentration must be greater than 100 mg/l, and the chloride ion concentration must be greater than 150 mg/l. This point must be taken into consideration when selecting a sea area.

2 Farming methods

2.1 Key technical points for cage farming

Sea area selection: consideration must be given both to meeting the red drum's requirements for environmental conditions to the greatest extent possible and to meeting the special requirements of cage farming. The bottom sediment is best mud-sand or sand-mud, with clear, unpolluted water. The current speed in the sea area should be within 1 m/second, and areas with swirling currents should be avoided.

Mesh size requirements: because Sciaenops ocellatus does not have a well-developed dorsal fin, unlike @#@240@#, it escapes easily. Therefore, mesh size requirements are strict; the mesh size should be selected on the basis that the length of 2 single mesh bars is smaller than the body height of the fish, and it is best if a mesh can be broken without the fish escaping. As the fish grows, the mesh size should be adjusted accordingly to ensure good water exchange capacity. In daily management, special attention must be paid to whether the mesh is damaged or blocked, and problems must be dealt with promptly to avoid unnecessary losses.

2.2 Key points of pond culture techniques

The sea area selected must meet the growth requirements of Sciaenops ocellatus and the conditions for pond culture. The pond bottom should be flat, the bottom sediment should be mud-sand or sand-mud, there should be no pollution around the pond, the water should be clear, and water intake and drainage should be convenient. In daily management, attention must be paid to flood prevention and flood control; drainage ditches must be kept clear, and special attention must be paid to preventing escape at the sluice gates. For pond clearing and disinfection, new ponds must be leveled and thoroughly disinfected; especially for old ponds that have been @#@233@#@ for many years, the water must be drained, and after sun-drying, the silt must be thoroughly removed, and after disinfection with quicklime, water should be added to a depth of 1 m and left to soak for later use. In daily management, attention must be paid to disinfecting the pond water after a period of culture, hanging sterilization bags or using a stabilized chlorine dioxide disinfectant to prevent disease outbreaks.

3 Feeding methods

It can be cultured alone or polycultured, and attention must be paid to stocking density. At present, most farmers prefer polyculture. This fish is highly active, is not strict about feed requirements, and tolerates starvation. First, it can serve as a "cleaner" and improve feed utilization; second, because this fish is highly active, it can increase oxygen.

4 Strict water temperature requirements

Water temperature is an important factor in the growth of Sciaenops ocellatus. According to farming experience in recent years, changes in salinity have little effect on the growth of Sciaenops ocellatus, but temperature is very important. Production practice has proven that temperatures below 18°C have a great impact on Sciaenops ocellatus; as the temperature decreases, food intake gradually declines, and below 8°C it stops feeding and deaths occur. Therefore, during the overwintering period, the water temperature must be kept above 10°C. During high-temperature periods, when the average pond water temperature reaches 26-28°C, this fish is very active and grows very quickly.

5 Fry sources

Ensure good quality when purchasing fry, and select fry with uniform body shape, robust constitution, intact scales, and no injuries or diseases. The fry come from South Korea, and now they are also bred domestically, with a size of 2-3 cm.

6 Scientific management

6.1 Time for stocking fry

Choose the time at neap tide or slack tide, on sunny afternoons in low-temperature seasons, and in the cool morning or evening in high-temperature seasons. Never pour them in directly; they should be given a period to adapt.

6.2 Feed and feeding

The red drum is an omnivorous fish that feeds mainly on animal food. The feed is mainly fresh or frozen mixed fish and shrimp, which are ground into a minced-meat consistency and fed by broadcasting according to a "slow-fast-slow" rhythm. The feeding amount can be 8%-10% of the fish body weight.

7 Disease prevention and control

This fish has strong disease resistance and few diseases, but one must not be careless. Pay attention to daily prevention and scientific management; maintain excellent water quality, keep stocking density reasonable, and pay attention to nutritional balance. Feed fresh, high-quality feed; the feed should be cleanly handled and free of pollution, and it is best to feed compound feed to enhance disease resistance. Prevent the introduction of pathogenic bacteria; fry must be quarantined and disinfected before entering the pond, fed in appropriate amounts to reduce leftover feed, and daily management should be strengthened so as to prevent problems before they occur. At present, the main diseases found are: lymphocystis disease, which should be prevented mainly; as well as vibriosis, streptococcosis, and anaerobic bacterial disease, which are treated with antibiotic drugs.