Identifying and Solutions for Mossy and Slimy Shrimp

Moss and Slime Disease in Shrimp: Causes, Symptoms, and Treatment

What is Moss and Slime Disease in Shrimp?

Shrimp affected by moss and slime disease develop a greenish-black algae-like layer covering parts or the entire body. This condition makes movement difficult, hinders molting, and slows growth.

Shrimp often experience calcification and slime buildup on the cephalothorax and appendages, sometimes leading to blackened gills. While this disease is not as severe as viral or bacterial infections, it significantly impacts shrimp health, quality, and farming productivity.

How to Identify Slime-Coated Shrimp

Moss and slime disease occurs due to bacteria, protozoa, and inorganic substances adhering to the shrimp’s shell. It is commonly found in polluted pond environments with excessive algae growth. The disease can be identified through the following symptoms:

• A slimy, slippery mucus layer with a greenish or black tint forms on the shrimp’s shell.
• Darkened or blackened gills and appendages.
• A green or greenish-black algae layer covering the shrimp’s body.
• Impaired movement due to slime accumulation on the cephalothorax, gills, and head.
• Reduced or complete loss of appetite.
• Shrimp swim sluggishly near pond edges, and in severe cases, shell damage allows bacterial infections, causing scattered deaths.
• Shrimp float to the surface early in the morning and gather in oxygen-rich areas due to clogged gills hindering respiration.

Causes of Moss and Slime Disease in Shrimp

The main causes include:

• Bacteria (Vibrio sp.), algae (blue-green algae), fungi, protozoa, and other microorganisms attach to the shrimp’s shell, forming a slime layer.
• Weakened shrimp struggle to clean their bodies or molt normally, allowing dirt and biofilm to accumulate.
• Poor water quality and excess organic matter promote the growth of microorganisms that adhere to shrimp shells.
• High or low salinity levels disrupt molting, preventing the shrimp from shedding their old shells, leading to slime buildup.

Prevention Measures

• Proper pond preparation before stocking shrimp.
• Effective environmental management, avoiding excess feed accumulation.
• Controlling algae growth to prevent overpopulation.
• Ensuring adequate oxygen and nutrition to support shrimp molting.

Treatment Methods

If shrimp show signs of moss and slime disease:

• Water exchange: Replace 30% of pond water to reduce harmful algae, fungi, and bacteria.
• Feed management: Reduce feed by 5-10% temporarily to prevent excessive ammonia (NH₃) buildup.
• Nutritional support: Add Vitamin C and EM probiotics to shrimp feed to boost immunity and reduce stress.
• Mineral supplementation: Apply Dolomite or other mineral enhancers to prevent soft shells and promote molting.
• Molting assistance: If shrimp fail to molt, apply BKC (80% concentration) to stimulate the process.
• Chemical treatment: Formalin (35-40%) can be used at 25-30 ppm with continuous aeration. However, caution is advised due to potential toxicity.

Conclusion

Moss and slime disease can affect shrimp from postlarvae to adulthood in species such as black tiger shrimp, white-leg shrimp, and giant freshwater prawns. If left untreated, it leads to stunted growth and reduced farming productivity. Regular monitoring and proactive prevention are crucial for maintaining shrimp health and achieving a successful harvest.