Loose Shell Syndrome in Shrimp: Symptoms, Management, Prevention, Causes, Control, and Treatment

Loose shell syndrome (LSS) is a chronic disease affecting farmed shrimp, particularly in India’s black tiger shrimp (Penaeus monodon) in 1998. The disease is characterized by soft shells, narrowed space between muscle tissue and shell, and hepatopancreas, which results in sluggish growth and reduced feed conversion efficiency. LSS has caused heavy economic losses to the shrimp farming industry, with a prevalence rate of over 50% in the coastal areas of Andhra Pradesh in 2002.

The knowledge of LSS on farmed vannamei shrimp is limited, and factors such as water quality parameters, mean body weight, and daily growth rate are selected for study to compare the tissue structure of normal and LSS-infected shrimp. The shrimp growth from 35 days of culture, poor meat quality, and chronic diseases are associated with LSS, posing significant challenges to the shrimp industry.

Loose Shell Syndrome in Shrimp

Impact of Loose Shell Syndrome on Shrimp

Loose Shell Syndrome (LSS) is a chronic disease that poses a significant threat to India’s black tiger shrimp industry. The disease leads to progressive mortality, reduced survival rates, and lower production levels. LSS-infected shrimp exhibit sluggish behavior, soft shells, and a gap between the muscle and shell. Indian shrimp farms in 1998 have since become more common. Studies in the early 2000s found that LSS affected around 23-27% of shrimp farms in different parts of India. In 2004 report says that over half of the farms surveyed had experienced LSS.

Causes of Loose Shell Syndrome in Shrimp

Loose Shell Syndrome (LSS) in shrimp is not significantly affected by water quality factors like salinity, dissolved oxygen, and temperature but rather by changes in pH levels. Researchers in India have identified four bacterial species – V. harveyi, V. alginolyticus, V. fluvialis, and V. parahaemolyticus – as possible causes of LSS, along with mineral deficiencies, poor water quality, and inadequate management practices.

The study suggests that Vibrio bacteria may play a role in developing LSS in L. vannamei. Feeding healthy shrimp with affected tissue resulted in LSS symptoms. Atrophied hepatopancreas, edema, and low lipid storage were observed in affected shrimp. Lymphoid organs showed necrosis and separation of tubules Viral-like particles are found infected with LSS in shrimp.

What are the Signs and Symptoms of Loose Shell Syndrome in Shrimp?

Slow, lethargic behavior
Soft, mushy flesh
Severely damaged shell with a layer of glue on the surface.
Lack of molting and bacteria clinging to the outer layer
Melanin pigment in the hepatopancreas and atrophied liver
Milky opaque color in the intestines
The visible gap between the muscle and the shell

In case you missed it: Systemic Vibriosis Management in Shrimp (Prawn): Disease Symptoms, Causes, Diagnosis, Treatment, Control, and Prevention

Diagnosis of Loose Shell Syndrome in Shrimp

Visual inspection of shrimp for symptoms such as soft and mushy flesh, slow movement, and damaged shells can be an initial indication of LSS.
Other methods for diagnosis include hemolymph analysis, histopathological examination, and bacterial isolation from hemolymph or tissue samples.
Hemolymph analysis can help detect changes in hemolymph chemistry and indicate the presence of bacteria or viruses.
Histopathological examination of shrimp tissues can provide insights into the extent and location of damage to various organs.
Bacterial isolation can help identify the species of bacteria that may be causing LSS. Polymerase chain reaction (PCR) assays can detect specific bacterial species in shrimp samples.

Control of Loose Shell Syndrome in Shrimp

Improve Water Quality: Maintain good water quality by controlling pH levels and minimizing pollutants and toxins in the water.
Provide Adequate Nutrition: Feed the shrimp a well-balanced diet to maintain their health and strengthen their shells.
Reduce Stress: Avoid overcrowding and minimize handling to reduce stress levels in shrimp.
Add Calcium: Supplement the diet with calcium to help maintain the shell’s integrity.
Use Antibiotics: In cases of bacterial infection, antibiotics may be used to treat the disease.
Provide Hiding Places: Shrimp should be provided with adequate hiding places to reduce predation risk and protect them from parasites.

Treatment of Loose Shell Syndrome in Shrimp

Loose shell syndrome treatment in shrimp, including antibiotics, the addition of calcium to the diet, and providing ample hiding places. Antibiotics such as oxytetracycline and florfenicol can be added to the water to reduce the bacterial load.
Calcium supplements can help to improve shell quality while providing hiding places that can reduce stress and improve overall health.
However, prevention is the best approach, and treatment should only be used as a last option after all other preventative steps have been exhausted.

Prevention of Loose Shell Syndrome in Shrimp

Vibrio bacteria mainly cause loose Shell Syndrome in white shrimp, and preventive measures should focus on managing and preventing bacterial infections.
Farmers can prevent the disease by maintaining clean and high-quality water with proper pH and salinity levels, avoiding overcrowding to prevent stress and disease spread, practicing good farm hygiene by regularly cleaning tanks and equipment and disposing of waste, monitoring for signs of disease and isolating sick animals, and using only healthy, virus-free shrimp for stocking ponds or tanks.
To prevent Vibrio bacteria specifically, farmers should periodically disinfect the water and enhance the shrimps’ resistance with adequate minerals. These general preventive measures can help reduce the risk of Loose Shell Syndrome in shrimp farms.

In case you missed it: White Gut Disease Management in Shrimp: Symptoms, Causes, Control, Prevention, and Treatment

Conclusion

Loose shell syndrome is a condition that can affect shrimp and lead to significant economic losses for farmers. It is caused by poor water quality, overfeeding, stress, and bacterial infections, primarily Vibrio bacteria. Prevention through proper water management, hygiene, and disease monitoring is essential.

Treatment options include antibiotics, calcium supplementation, and providing hiding places. However, prevention is the best approach to avoid economic losses. Shrimp farmers can maintain a healthy environment by implementing preventive measures and minimizing the risk of loose-shell syndrome outbreaks.

Loose Shell Syndrome in Shrimp: Symptoms, Management, Prevention, Causes, Control, and Treatment

Table of Contents