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
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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 L