A Summary of Practical Experience and Methods for Preventing and Treating Diseases in Sea Bass

Sea bass has relatively strong disease resistance and is not prone to illness under natural conditions. However, in artificial high-density farming, because its living environment and space undergo great changes, disease can easily be caused by even a slight lapse in care. Disease prevention must be strengthened, and drug disinfection of farming ponds and feeding platforms must be carried out regularly. If disease is found, treat it early. Common fish diseases include:

1. Enteritis

The diseased fish has a swollen abdomen and red and swollen anus, and when the abdomen is pressed, pale yellow mucus flows out. It is mainly caused by feeding stale or spoiled feed. For treatment, oxytetracycline can be mixed into bait and fed; use 10 grams of the drug per 50 kg of fish, reduce it by half from the second day onward, and feed it mixed with bait continuously for 6 days. Norfloxacin can also be used at 2 grams mixed into bait and fed.

2. Gill rot disease

The diseased fish has a dark body color, swims slowly away from the group at the water surface, and responds sluggishly to the outside environment. When the gill cover is opened, the gill filaments are pale and the gill lamellae are rotting. The cause of the disease is that after heavy rain the water quality becomes turbid, making the fish susceptible to infection. This is especially true in cage farming, where after heavy rain, upstream mud and sand flows strike the fish body, making sea bass highly susceptible to this disease, with very large losses. For treatment, 0.4 ppm strong chlorinated disinfectant can be splashed over the entire pond or cage for 3 consecutive days, and the treatment effect is relatively obvious.

3. Hemorrhagic disease

The base of the pectoral fins and dorsal fins of the diseased fish is red and swollen and congested, and the diseased fish moves slowly and its feeding decreases. This disease is caused by a virus and is highly contagious.

4. Saprolegniasis

This disease mostly occurs in winter and spring. Grayish-white cotton-like mycelium attaches to wounds on the body surface of the diseased fish. The fish body becomes weak and powerless and gradually dies. After infection, this disease spreads relatively quickly. At the same time, fry transportation and net-pulling operations should also be performed carefully to avoid injuring the fish body.

5. Parasitic disease

Small white spots appear on the body surface and fin rays of the diseased fish, and mucus increases at the parasitic sites. The diseased fish does not feed, behaves abnormally, and often swims in groups around the pond. Common parasites include Ichthyophthirius, Epistylis, Trichodina, and other species. For treatment, 20 ppm formalin can be splashed over the entire pond for 2 days. In treatment, use drugs such as trichlorfon and organophosphates with caution, otherwise it will cause drug poisoning in sea bass.

Harvest

Generally, after being raised until the end of that year, they can be caught as commercial fish and sold on the market. They can be caught all at once by draining the pond, or they can be sold in batches by seining with water retained according to changes in market demand. In the latter case, note that sea bass caught and netted should not be put back into the pond, because they will be injured by the net and die not long after returning to the pond.