Comprehensive Prevention and Control Plan for “Red Body” in Eel Farming

2026-06-05

I. What is red body, and what are its hazards?

In the cultivation of large‑scale prawns, red body coloration is classified into “stress‑induced red body” and “viral red body.” We focus here on the latter, which poses the greatest threat. According to PCR testing conducted over the past few years, more than 95% of cases of viral red body are attributable to White Spot Syndrome Virus (WSSV).

This disease is currently the most devastating threat to shrimp farming, particularly in low-salinity environments (specific gravity below 30). In the early stages, shrimp grow vigorously; however, once the disease strikes, losses can exceed 70%, sometimes even resulting in total crop failure. Yield plummets, feed conversion ratios soar, and substantial economic losses ensue. (A large amount of feed is administered in the early phase, yet the shrimp fail to emerge in the later stage!)

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II. What are the symptoms of red-body disease?

The prawns have a slightly reddish or pinkish body, an empty intestine and stomach, and exhibit “flying” behavior—commonly referred to as “taking off”—with extremely poor vitality; they can even be scooped up by hand. Dead prawns, regardless of size, do not float; instead, they sink to the bottom. Use a cast net to sample, or inspect the shrimp‑catching net for diseased individuals.

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III. Under what circumstances is red body disease likely to occur?

1. In ponds with low salinity (specific gravity below 30), especially in sections where water exchange is substantial, rapid changes in water quality can easily trigger stress, leading to red-body syndrome in shrimp.

2. The pond harbors hosts carrying WSSV, primarily wild shrimp and crabs (such as freshwater prawns and grass shrimp). Once these hosts become infected, they can readily transmit the virus to farmed shrimp, leading to disease outbreaks in the cultured species.

3. After heavy rainfall, shrimp are prone to stress‑induced molting and become more susceptible to infection when their condition is weakened.

(“Viral red body” is mostly due to shrimp that are already weakened and have developed “stress‑induced red body,” which, if their condition fails to improve, gradually progresses into “viral red body.”)

IV. How to prevent and control red body disease?

1. 1–2 months before stocking, remove host species (wild shrimp and crabs). Be sure to conduct a trial stocking prior to release.

2. Ensure that the shrimp postlarvae being stocked are free of WSSV. Typically, healthy postlarvae do not carry WSSV; however, if they are infected, red discoloration and mortality may occur even at the hatchery, which can be observed with the naked eye.

3. Fish that are prone to red body disease will remain susceptible year after year. In the early stages, feed them a diet with relatively high protein content or supplement their diet with more brine shrimp to strengthen their constitution; this will help improve their disease resistance in the later stages.

4. As long as feeding is taking place, mix the medication into the feed; we recommend “ Liver and Gallbladder Health ”+“ Five Yellow Detoxifying Liquid “Traditional Chinese medicine exhibits antibacterial and antiviral properties, enhancing the shrimp’s innate immunity, and has demonstrated promising results in controlling red body disease over the past few years.”

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5. When shrimp can be harvested, be sure to use nets to remove them. After a red-body outbreak, cross‑infection spreads very easily; most affected shrimp will swim along the pond edges. Place additional nets along the perimeter to maximize the removal of sick shrimp. In later stages, when the disease becomes severe, shrimp may lie motionless in the sediment and stop entering the nets. At this point, you can apply “...” as a dry‑spray treatment. Hein Vanguard “With mild stimulation and strong pathogen‑killing efficacy at the bottom, first thoroughly manage the disease‑prone environment, then supplement the feed with brine shrimp for a period to boost nutrition. (In cases of severe disease, shrimp may refuse feed but will still cling to and consume brine shrimp.) Once the environment is well‑controlled and their condition improved, symptoms will be significantly alleviated.”

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6. When heavy rain comes, sprinkle “ Stress Detox CE “It’s the best stress‑resistance product on the market.” It’s best to apply it before heavy rain to strengthen the shrimp’s health and minimize environmental stress. After rainfall, parameters such as salinity, temperature, bacterial levels, algal composition, and dissolved oxygen can all fluctuate significantly. This period is when shrimp are at their weakest and most susceptible to bacterial and viral infections, so it’s crucial to bolster their condition and enhance their disease resistance. Currently, feeding brine shrimp is too slow.

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